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Observations of anthropogenic global warming

Archive for November, 2009

The Copenhagen Diagnosis references

Posted by Ari Jokimäki on November 28, 2009

This is a linklist to the abstracts and full texts of the papers referenced in The Copenhagen Diagnosis, an update to the IPCC AR4.

UPDATE (May 25, 2010): link to the full text of Meinshausen et al. (2009) added, thanks to Anton for pointing it out, see the comment section below.
UPDATE (November 29, 2009): link to the full text of Benestad & Schmidt (2009) added, thanks to Paul Middents for pointing it out, see the comment section below.

Åkerman & Johansson (2008) “Thawing permafrost and thicker active layers in sub-arctic Sweden” [Abstract]

Alexander & Arblaster (2008) “Assessing trends in observed and modelled climate extremes over Australia in relation to future projections” [Abstract] [Full text]

Allan & Soden (2008) “Atmospheric Warming and the Amplification of Precipitation Extremes” [Abstract] [Full text]

Allen & Sherwood (2008) “Warming maximum in the tropical upper troposphere deduced from thermal winds” [Abstract] [Full text]

Allen et al. (2009) “Warming caused by cumulative carbon emissions towards the trillionth tonne” [Abstract] [Full text]

Alley et al. (2003) “Abrupt Climate Change” [Abstract] [Full text]

Allison et al. (2009) “Ice sheet mass balance and sea level” [Abstract]

Andronova & Schlesinger (2001) “Objective estimation of the probability density function for climate sensitivity” [Abstract]

Annan & Hargreaves (2006) “Using multiple observationally-based constraints to estimate climate sensitivity” [Abstract] [Full text]

Archer et al. (2009) “Ocean methane hydrates as a slow tipping point in the global carbon cycle” [Abstract] [Full text]

Arzel et al. (2005) “Sea ice evolution over the 20th and 21st centuries as simulated by current AOGCMs” [Abstract] [Full text]

Aumann et al. (2008) “Frequency of severe storms and global warming” [Abstract] [Full text]

Bahr et al. (2009) “Sea-level rise from glaciers and ice caps: A lower bound” [Abstract] [Full text]

Bakke et al. (2009) “Rapid oceanic and atmospheric changes during the Younger Dryas cold period” [Abstract] [Full text]

Bala et al. (2007) “Combined climate and carbon-cycle effects of large-scale deforestation” [Abstract] [Full text]

Barnett et al. (2008) “Human-Induced Changes in the Hydrology of the Western United States” [Abstract] [Full text]

Barrett et al. (2009) “Rapid recent warming on Rutford Ice Stream, West Antarctica, from borehole thermometry” [Abstract]

Benestad & Schmidt (2009) “Solar trends and global warming” [Abstract] [Full text]

Berger (1978) “Long-Term Variations of Daily Insolation and Quaternary Climatic Changes” [Abstract]

Berger & Loutre (1991) “Insolation values for the climate of the last 10 million years” [Abstract]

Berger et al. (1998) “Sensitivity of the LLN climate model to the astronomical and CO2 forcings over the last 200 ky” [Abstract]

Betts et al. (2000) “Offset of the potential carbon sink from boreal forestation by decreases in surface albedo” [Abstract]

Betts et al. (2007) “Projected increase in continental runoff due to plant responses to increasing carbon dioxide” [Abstract]

Biggs et al. (2009) “Turning back from the brink: Detecting an impending regime shift in time to avert it” [Abstract] [Full text]

Bindoff et al. (2007) “Observations: Oceanic Climate Change and Sea Level” (IPCC AR4, chapter 5) [Abstract] [Full text]

Bondeau et al. (2007) “Modelling the role of agriculture for the 20th century global terrestrial carbon balance” [Abstract] [Full text]

Bony et al. (2006) “How Well Do We Understand and Evaluate Climate Change Feedback Processes?” [Abstract] [Full text]

Booth et al. (2009 submitted) “Global warming uncertainties due to carbon cycle feedbacks exceed those due to CO2 emissions”

Braun & Humbert (2009) “Recent Retreat of Wilkins Ice Shelf Reveals New Insights in Ice Shelf Breakup Mechanisms” [Abstract]

Brewer (2009) “A changing ocean seen with clarity” [Abstract]

Brook et al. (2008) “Potential for abrupt changes in atmospheric methane” (A report chapter) [Full text]

Canadell et al. (2007) “Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks” [Abstract] [Full text]

Cavalieri & Parkinson (2008) “Antarctic sea ice variability and trends, 1979–2006” [Abstract]

Cazanave et al. (2008) “Sea level budget over 2003–2008: A reevaluation from GRACE space gravimetry, satellite altimetry and Argo” [Abstract] [Full text]

CCSP (2008a) “Weather and Climate Extremes in a Changing Climate” (A report) [Abstract]

CCSP (2008b) “Abrupt Climate Change” (A report) [Abstract]

Chang et al. (2008) “Oceanic link between abrupt changes in the North Atlantic Ocean and the African monsoon” [Abstract] [Full text]

Chapman & Walsh (2007) “A Synthesis of Antarctic Temperatures” [Abstract] [Full text]

Chen et al. (2006) “Antarctic mass rates from GRACE” [Abstract] [Full text]

Church & White (2006) “A 20th century acceleration in global sea-level rise” [Abstract] [Full text]

Clark et al. (1999) “Northern Hemisphere Ice-Sheet Influences on Global Climate Change” [Abstract] [Full text]

Cogley (2009) “Geodetic and direct mass-balance measurements: comparison and joint analysis” [Abstract] [Full text]

Comiso & Nishio (2008) “Trends in the sea ice cover using enhanced and compatible AMSR-E, SSM/I, and SMMR data” [Abstract]

Cook et al. (2005) “Retreating Glacier Fronts on the Antarctic Peninsula over the Past Half-Century” [Abstract]

Cook & Vizy (2006) “Coupled Model Simulations of the West African Monsoon System: Twentieth- and Twenty-First-Century Simulations” [Abstract] [Full text]

Cook & Vizy (2008) “Effects of Twenty-First-Century Climate Change on the Amazon Rain Forest” [Abstract]

Cox et al. (2004) “Amazonian forest dieback under climate-carbon cycle projections for the 21st century” [Abstract] [Full text]

Cox et al. (2008) “Increasing risk of Amazonian drought due to decreasing aerosol pollution” [Abstract] [Full text]

Cox & Jones (2008) “Illuminating the Modern Dance of Climate and CO2 [Abstract]

Cruz et al. (2008) “Probabilistic simulations of the impact of increasing leaf-level atmospheric carbon dioxide on the global land surface” [Abstract]

Cui & Graf (2008) “Recent land cover changes on the Tibetan Plateau: a review” [Abstract]

Curry et al. (2003) “A change in the freshwater balance of the Atlantic Ocean over the past four decades” [Abstract] [Full text]

Dakos et al. (2008) “Slowing down as an early warning signal for abrupt climate change” [Abstract] [Full text]

Delworth et al. (2008) “The Potential for Abrupt Change in the Atlantic Meridional Overturning Circulation” (A report chapter) [Abstract] [Full text]

Dessler et al. (2008) “Water-vapor climate feedback inferred from climate fluctuations, 2003–2008” [Abstract] [Full text]

Domingues et al. (2008) “Improved estimates of upper-ocean warming and multi-decadal sea-level rise” [Abstract] [Full text]

Dorrepaal et al. (2009) “Carbon respiration from subsurface peat accelerated by climate warming in the subarctic” [Abstract]

Easterling & Wehner (2009) “Is the climate warming or cooling?” [Abstract] [Full text]

Eby et al. (2009) “Lifetime of Anthropogenic Climate Change: Millennial Time Scales of Potential CO2 and Surface Temperature Perturbations” [Abstract] [Full text]

Eisenman & Wettlaufer (2008) “Nonlinear threshold behavior during the loss of Arctic sea ice” [Abstract] [Full text]

Elsner et al. (2008) “The increasing intensity of the strongest tropical cyclones” [Abstract] [Full text]

Emanuel et al. (2008) “Hurricanes and Global Warming: Results from Downscaling IPCC AR4 Simulations” [Abstract] [Full text]

England et al. (2009) “Constraining future greenhouse gas emissions by a cumulative target” [Abstract] [Full text]

EPICA community members (2004) “Eight glacial cycles from an Antarctic ice core” [Abstract]

Esper et al. (2002) “Low-Frequency Signals in Long Tree-Ring Chronologies for Reconstructing Past Temperature Variability” [Abstract] [Full text]

Fabry et al. (2008) “Impacts of ocean acidification on marine fauna and ecosystem processes” [Abstract] [Full text]

Fargione et al. (2008) “Land Clearing and the Biofuel Carbon Debt” [Abstract] [Full text]

Fischer et al. (2007) “Contribution of land-atmosphere coupling to recent European summer heat waves” [Abstract] [Full text]

Flanner et al. (2007) “Present-day climate forcing and response from black carbon in snow” [Abstract] [Full text]

Frame et al. (2005) “Constraining climate forecasts: The role of prior assumptions” [Abstract] [Full text]

Frederick et al. (2004) (GRL has Krabill as first author) “Greenland Ice Sheet: Increased coastal thinning” [Abstract] [Full text]

Friedlingstein et al. (2006) “Climate–Carbon Cycle Feedback Analysis: Results from the C4MIP Model Intercomparison” [Abstract] [Full text]

Fyke & Weaver (2006) “The Effect of Potential Future Climate Change on the Marine Methane Hydrate Stability Zone” [Abstract] [Full text]

Galloway et al. (2008) “Transformation of the Nitrogen Cycle: Recent Trends, Questions, and Potential Solutions” [Abstract] [Full text]

Ganopolski & Roche (2009) “On the nature of lead–lag relationships during glacial–interglacial climate transitions” [Abstract]

Goosse et al. (2009) “Consistent past half-century trends in the atmosphere, the sea ice and the ocean at high southern latitudes” [Abstract]

Gedney et al. (2006) “Detection of a direct carbon dioxide effect in continental river runoff records” [Abstract] [Full text]

Gleason et al. (2008) “A Revised U.S. Climate Extremes Index” [Abstract] [Full text]

Guan et al. (2009) “Journey to world top emitter: An analysis of the driving forces of China’s recent CO2 emissions surge” [Abstract] [Full text]

Guttal & Jayaprakash (2008) “Changing skewness: an early warning signal of regime shifts in ecosystems” [Abstract] [Full text]

Guttal & Jayaprakash (2009) “Spatial variance and spatial skewness: leading indicators of regime shifts in spatial ecological systems” [Abstract] [Full text]

Hagos & Cook (2007) “Dynamics of the West African Monsoon Jump” [Abstract] [Full text]

Hall et al. (2008) “Greenland ice sheet surface temperature, melt and mass loss: 2000-06” [Abstract]

Hanna et al. (2008) “Increased Runoff from Melt from the Greenland Ice Sheet: A Response to Global Warming” [Abstract] [Full text]

Hanna et al. (2009) “Hydrologic response of the Greenland ice sheet: the role of oceanographic warming” [Abstract] [Full text]

Hansen & Østerhus (2007) “Faroe Bank Channel overflow 1995–2005” [Abstract]

Harris et al. (2008) “Permafrost and climate in Europe: Monitoring and modelling thermal, geomorphological and geotechnical responses” [Abstract]

Hays et al. (1976) “Variations in the Earth’s Orbit: Pacemaker of the Ice Ages” [Abstract] [Full text]

Haywood et al. (2007) “The mid Pliocene Warm Period: A Test-bed for Integrating Data and Models” [Abstract]

Hock et al. (2009) “Mountain glaciers and ice caps around Antarctica make a large sea‐level rise contribution” [Abstract]

Hofmann & Schellnhuber (2009) “Oceanic acidification affects marine carbon pump and triggers extended marine oxygen holes” [Abstract] [Full text]

Hofmann & Rahmstorf (2009) “On the stability of the Atlantic meridional overturning circulation” [Abstract] [Full text]

Holland et al. (2006) “Future abrupt reductions in the summer Arctic sea ice” [Abstract] [Full text]

Holland et al. (2008) “Acceleration of Jakobshavn Isbræ triggered by warm subsurface ocean waters” [Abstract] [Full text]

House et al. (2008) “What do recent advances in quantifying climate and carbon cycle uncertainties mean for climate policy?” [Abstract] [Full text]

Howat et al. (2007) “Rapid Changes in Ice Discharge from Greenland Outlet Glaciers” [Abstract] [Full text]

Howat et al. (2008) “Rates of southeast Greenland ice volume loss from combined ICESat and ASTER observations” [Abstract]

Hoyos et al. (2006) “Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity” [Abstract]

Hyvönen et al. (2007) “The likely impact of elevated [CO2], nitrogen deposition, increased temperature and management on carbon sequestration in temperate and boreal forest ecosystems: a literature review” [Abstract] [Full text]

IPCC (2001) “Climate Change 2001: The Scientific Basis” (IPCC TAR) [Abstract]

IPCC (2007) “Climate Change 2007: The Physical Science Basis” (IPCC AR4) [Abstract]

IPCC (2007) “Summary for Policymakers” (IPCC AR4) [Full text]

Jansen et al. (2007) “Palaeoclimate” (IPCC AR4, chapter 6) [Abstract] [Full text]

Jin et al. (2007) “Changes in permafrost environments along the Qinghai–Tibet engineering corridor induced by anthropogenic activities and climate warming” [Abstract]

Johannessen et al. (2005) “Recent Ice-Sheet Growth in the Interior of Greenland” [Abstract] [Full text]

Johnson et al. (2007) “Decadal water mass variations along 20°W in the Northeastern Atlantic Ocean” [Abstract] [Full text]

Johnson et al. (2008) “Reduced Antarctic meridional overturning circulation reaches the North Atlantic Ocean” [Abstract]

Johnson et al. (2008) “Warming and Freshening in the Abyssal Southeastern Indian Ocean” [Abstract] [Full text]

Jones et al. (2008) “Human contribution to rapidly increasing frequency of very warm Northern Hemisphere summers” [Abstract]

Jones et al. (2008) (GRL has Perovich as first author) “Sunlight, water, and ice: Extreme Arctic sea ice melt during the summer of 2007” [Abstract] [Full text]

Jones et al. (2009) “Committed terrestrial ecosystem changes due to climate change” [Abstract]

Joos & Spahni (2008) “Rates of change in natural and anthropogenic radiative forcing over the past 20,000 years” [Abstract] [Full text]

Kaser et al. (2006) “Mass balance of glaciers and ice caps: Consensus estimates for 1961–2004” [Abstract] [Full text]

Kaufman et al. (2009) “Recent Warming Reverses Long-Term Arctic Cooling” [Abstract] [Full text]

Kharin et al. (2007) “Changes in Temperature and Precipitation Extremes in the IPCC Ensemble of Global Coupled Model Simulations” [Abstract] [Full text]

Khvorostyanov et al. (2008) “Vulnerability of east Siberia’s frozen carbon stores to future warming” [Abstract]

Khvorostyanov et al. (2008) “Vulnerability of permafrost carbon to global warming. Part I: model description and role of heat generated by organic matter decomposition” [Abstract]

Knutti & Hegerl (2008) “The equilibrium sensitivity of the Earth’s temperature to radiation changes” [Abstract] [Full text]

Krabill et al. (2000) “Greenland Ice Sheet: High-Elevation Balance and Peripheral Thinning” [Abstract] [Full text]

Krabill et al. (2004) (this was already above as Frederick et al.) “Greenland Ice Sheet: Increased coastal thinning” [Abstract] [Full text]

Kriegler et al. (2009) “Imprecise probability assessment of tipping points in the climate system” [Abstract] [Full text]

Kürschner et al. (1996) “Oak leaves as biosensors of late Neogene and early Pleistocene paleoatmospheric CO2 concentrations” [Abstract]

Kwok & Rothrock (2009) “Decline in Arctic sea ice thickness from submarine and ICESat records: 1958–2008” [Abstract]

Lam et al. (2009) “Revising the nitrogen cycle in the Peruvian oxygen minimum zone” [Abstract] [Full text]

Latif & Keenlyside (2008) “El Niño/Southern Oscillation response to global warming” [Abstract]

Lawrence & Slater (2005) “A projection of severe near-surface permafrost degradation during the 21st century” [Abstract] [Full text]

Lawrence et al. (2008) “Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss” [Abstract] [Full text]

Le Quéré et al. (2007) “Saturation of the Southern Ocean CO2 Sink Due to Recent Climate Change” [Abstract] [Full text]

Le Quéré et al. (2009) “Trends in the sources and sinks of carbon dioxide” [Abstract]

Lean & Rind (2008) “How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006” [Abstract] [Full text]

Lean & Rind (2009) “How will Earth’s surface temperature change in future decades?” [Abstract] [Full text]

Lefebvre et al. (2004) “Influence of the Southern Annular Mode on the sea ice–ocean system” [Abstract] [Full text]

Lemke et al. (2007) “Observations: Changes in Snow, Ice and Frozen Ground” (IPCC AR4 chapter 4) [Abstract] [Full text]

Lenton et al. (2008) “Tipping elements in the Earth’s climate system” [Abstract] [Full text]

Lenton et al. (2009) “Using GENIE to study a tipping point in the climate system” [Abstract] [Full text]

Lettenmaier & Milly (2009) “Land waters and sea level” [Abstract]

Lindsay et al. (2009) “Arctic Sea Ice Retreat in 2007 Follows Thinning Trend” [Abstract] [Full text]

Livina & Lenton (2007) “A modified method for detecting incipient bifurcations in a dynamical system” [Abstract] [Full text]

Lombard et al. (2006) “Perspectives on present-day sea level change: a tribute to Christian le Provost” [Abstract] [Full text]

Loulergue et al. (2008) “Orbital and millennial-scale features of atmospheric CH4 over the past 800,000 years” [Abstract] [Full text]

Lovenduski et al. (2008) “Toward a mechanistic understanding of the decadal trends in the Southern Ocean carbon sink” [Abstract] [Full text]

Luthcke et al. (2006) “Recent Greenland Ice Mass Loss by Drainage System from Satellite Gravity Observations” [Abstract]

Lüthi et al. (2008) “High-resolution carbon dioxide concentration record 650,000–800,000 years before present” [Abstract]

Malhi et al. (2008) “Climate Change, Deforestation, and the Fate of the Amazon” [Abstract] [Full text]

Malhi et al. (2009) “Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest” [Abstract] [Full text]

Mann et al. (1998) “Global-scale temperature patterns and climate forcing over the past six centuries” [Abstract] [Full text]

Mann et al. (1999) “Northern hemisphere temperatures during the past millennium: Inferences, uncertainties, and limitations” [Abstract] [Full text]

Mann et al. (2008) “Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia” [Abstract] [Full text]

Mann et al. (2009) “Atlantic hurricanes and climate over the past 1,500 years” [Abstract] [Full text]

Mann et al. (2009) “Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly” [Abstract]

Marsh et al. (2009) “Preliminary investigation into the severe thunderstorm environment of Europe simulated by the Community Climate System Model 3” [Abstract] [Full text]

Matthews & Caldeira (2008) “Stabilizing climate requires near-zero emissions” [Abstract] [Full text]

McIntyre & McKitrick (2003) “Corrections to the Mann et. al. (1998) Proxy Data Base and Northern Hemispheric Average Temperature Series” [Abstract]

McIntyre & McKitrick (2005) “Hockey sticks, principal components, and spurious significance” [Abstract] [Full text]

McIntyre & McKitrick (2005) “The M&M critique of the MBH98 northern hemisphere climate index: Update and implications” [Abstract] [Full text]

McNeil & Matear (2007) “Climate change feedbacks on future oceanic acidification” [Abstract]

McNeil & Matear (2008) “Southern Ocean acidification: A tipping point at 450-ppm atmospheric CO2 [Abstract] [Full text]

Meehl et al. (2004) “Combinations of Natural and Anthropogenic Forcings in Twentieth-Century Climate” [Abstract] [Full text]

Meehl et al. (2007a) “Global Climate Projections” (IPCC AR4 chapter 10) [Abstract] [Full text]

Meehl et al. (2007b) “Contributions of natural and anthropogenic forcing to changes in temperature extremes over the United States” [Abstract] [Full text]

Meehl et al. (2008) “Effects of Black Carbon Aerosols on the Indian Monsoon” [Abstract] [Full text]

Meier et al. (2007) “Glaciers Dominate Eustatic Sea-Level Rise in the 21st Century” [Abstract]

Meinshausen et al. (2009) “Greenhouse-gas emission targets for limiting global warming to 2 °C” [Abstract] [Full text]

Mercado et al. (2009) “Impact of changes in diffuse radiation on the global land carbon sink” [Abstract] [Full text]

Metzl (2009) “Decadal increase of oceanic carbon dioxide in Southern Indian Ocean surface waters (1991–2007)” [Abstract]

Moberg et al. (2005) “Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data” [Abstract] [Full text]

Monaghan et al. (2008) “Recent variability and trends of Antarctic near-surface temperature” [Abstract] [Full text]

Mote (2007) “Greenland surface melt trends 1973–2007: Evidence of a large increase in 2007” [Abstract]

Moy et al. (2009) “Reduced calcification in modern Southern Ocean planktonic foraminifera” [Abstract] [Full text]

Nakicenovic et al. (2000) “IPCC Special Report on Emissions Scenarios” [Abstract]

NASA Goddard Institute for Space Studies (2009) “GISS Surface
Temperature Analysis. Global Temperature Trends: 2008 Annual

Nghiem et al. (2007) “Rapid reduction of Arctic perennial sea ice” [Abstract] [Full text]

Nicholls et al. (2007) “Coastal Systems and Low-Lying Areas” (IPCC AR4 WG2 chapter 6) [Abstract] [Full text]

NOAA (2009) “State of the Climate” [Abstract]

NRC (National Research Council) (2006) “Surface Temperature Reconstructions for the Last 2,000 Years” [Abstract]

NSDIC – National Snow and Ice Data Center (2009) “Arctic sea ice extent remains low; 2009 sees third-lowest mark” [Abstract]

Oerlemans et al. (2007) “Reconstructing the glacier contribution to sea-level rise back to 1850” [Abstract] [Full text]

Oppo et al. (2009) “2,000-year-long temperature and hydrology reconstructions from the Indo-Pacific warm pool” [Abstract] [Full text]

Orr et al. (2005) “Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms” [Abstract] [Full text]

Orr et al. (2009) “Amplified acidification of the Arctic Ocean” [Abstract] [Full text]

Oschlies et al. (2008) “Simulated 21st century’s increase in oceanic suboxia by CO2-enhanced biotic carbon export” [Abstract] [Full text]

Pall et al. (2007) “Testing the Clausius–Clapeyron constraint on changes in extreme precipitation under CO2 warming” [Abstract]

Patricola & Cook (2008) “Atmosphere/vegetation feedbacks: A mechanism for abrupt climate change over northern Africa” [Abstract]

Pearson & Palmer (1999) “Middle Eocene Seawater pH and Atmospheric Carbon Dioxide Concentrations” [Abstract] [Full text]

Pedersen et al. (2009) “A new sea ice albedo scheme including melt ponds for ECHAM5 general circulation model” [Abstract]

Perovich et al. (2007) “Increasing solar heating of the Arctic Ocean and adjacent seas, 1979–2005: Attribution and role in the ice-albedo feedback” [Abstract] [Full text]

Petrenko et al. (2009) 14CH4 Measurements in Greenland Ice: Investigating Last Glacial Termination CH4 Sources” [Abstract] [Full text]

Pfeffer et al. (2008) “Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise” [Abstract]

Phillips et al. (2009) “Drought Sensitivity of the Amazon Rainforest” [Abstract] [Full text]

Piao et al. (2007) “Changes in climate and land use have a larger direct impact than rising CO2 on global river runoff trends” [Abstract] [Full text]

Pielke et al. (2007) “An overview of regional land-use and land-cover impacts on rainfall” [Abstract] [Full text]

Pitman et al. (2007) “The impact of climate change on the risk of forest and grassland fires in Australia” [Abstract] [Full text]

Pitman et al. (2009) “Uncertainties in climate responses to past land cover change: First results from the LUCID intercomparison study” [Abstract] [Full text]

Pollard & DeConto (2009) “Modelling West Antarctic ice sheet growth and collapse through the past five million years” [Abstract] [Full text]

Polyakov et al. (2004) “Variability of the Intermediate Atlantic Water of the Arctic Ocean over the Last 100 Years” [Abstract] [Full text]

Portmann et al. (2009) “Spatial and seasonal patterns in climate change, temperatures, and precipitation across the United States” (the report has the name of this paper wrong) [Abstract] [Full text]

Pritchard & Vaughan (2007) “Widespread acceleration of tidewater glaciers on the Antarctic Peninsula” [Abstract]

Pritchard et al. (2009) “Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets” [Abstract]

Rahmstorf (2007) “A Semi-Empirical Approach to Projecting Future Sea-Level Rise” [Abstract] [Full text]

Rahmstorf (2007) “Recent Climate Observations Compared to Projections” [Abstract] [Full text]

Ramanathan et al. (2005) “Atmospheric brown clouds: Impacts on South Asian climate and hydrological cycle” [Abstract] [Full text]

Ramanathan & Carmichael (2008) “Global and regional climate changes due to black carbon” [Abstract] [Full text]

Raupach et al. (2007) “Global and regional drivers of accelerating CO2 emissions” [Abstract] [Full text]

Raymo et al. (1996) “Mid-Pliocene warmth: stronger greenhouse and stronger conveyor” [Abstract]

Rayner et al. (2006) “Improved Analyses of Changes and Uncertainties in Sea Surface Temperature Measured In Situ since the Mid-Nineteenth Century: The HadSST2 Dataset” [Abstract] [Full text]

Reichstein et al. (2006) “Reduction of ecosystem productivity and respiration during the European summer 2003 climate anomaly: a joint flux tower, remote sensing and modelling analysis” [Abstract]

Repo et al. (2009) “Large N2O emissions from cryoturbated peat soil in tundra” [Abstract]

Richardson et al. (2009) “Climate Change: Global Risks, Challenges & Decisions. Synthesis Report of the Copenhagen Climate Congress” [Abstract] [Full text]

Riebesell et al. (2009) “Sensitivities of marine carbon fluxes to ocean
(not found, perhaps not yet published? Journal is said to be Proceedings of the National Academy of Sciences but no detailed reference is given.)

Rigby et al. (2008) “Renewed growth of atmospheric methane” [Abstract] [Full text]

Rignot et al. (2004) “Accelerated ice discharge from the Antarctic Peninsula following the collapse of Larsen B ice shelf” [Abstract] [Full text]

Rignot et al. (2006) “Changes in ice dynamics and mass balance of the Antarctic ice sheet” [Abstract] [Full text]

Rignot & Kanagaratnam (2006) “Changes in the Velocity Structure of the Greenland Ice Sheet” [Abstract]

Rignot (2008a) “Changes in West Antarctic ice stream dynamics observed with ALOS PALSAR data” [Abstract]

Rignot et al. (2008b) “Recent Antarctic ice mass loss from radar interferometry and regional climate modelling” [Abstract] [Full text]

Rignot et al. (2008) “Mass balance of the Greenland ice sheet from 1958 to 2007” [Abstract]

Rintoul et al. (2007) “Rapid freshening of Antarctic Bottom Water formed in the Indian and Pacific oceans” [Abstract]

Rohling et al. (2008) “High rates of sea-level rise during the last interglacial period” [Abstract] [Full text]

Rosa & Seibel (2008) “Synergistic effects of climate-related variables suggest future physiological impairment in a top oceanic predator” [Abstract]

Rotstayn & Lohmann (2002) “Tropical Rainfall Trends and the Indirect Aerosol Effect” [Abstract] [Full text]

Rutherford et al. (2005) “Proxy-Based Northern Hemisphere Surface Temperature Reconstructions: Sensitivity to Method, Predictor Network, Target Season, and Target Domain” [Abstract]

Sabine et al. (2004) “The Oceanic Sink for Anthropogenic CO2 [Abstract] [Full text]

Salazar et al. (2007) “Climate change consequences on the biome distribution in tropical South America” [Abstract] [Full text]

Santer et al. (2007) “Identification of human-induced changes in atmospheric moisture content” [Abstract] [Full text]

Saunders & Lea et al. (2008) “Large contribution of sea surface warming to recent increase in Atlantic hurricane activity” [Abstract] [Full text]

Scambos et al. (2004) “Glacier acceleration and thinning after ice shelf collapse in the Larsen B embayment, Antarctica” [Abstract] [Full text]

Schellnhuber et al. (2009) “Tipping elements in the Earth System” (not found, perhaps not yet published? Journal is said to be Proceedings of the National Academy of Sciences but no detailed reference is given.)

Scholze et al. (2006) “A climate-change risk analysis for world ecosystems” [Abstract] [Full text]

Schuster et al. (2009) “Trends in North Atlantic sea-surface pCO2 from 1990 to 2006″ [Abstract]

Schuur et al. (2008) “Vulnerability of Permafrost Carbon to Climate Change: Implications for the Global Carbon Cycle” [Abstract] [Full text]

Shackleton (2000) “The 100,000-Year Ice-Age Cycle Identified and Found to Lag Temperature, Carbon Dioxide, and Orbital Eccentricity” [Abstract] [Full text]

Sheffield & Wood (2008) “Global Trends and Variability in Soil Moisture and Drought Characteristics, 1950–2000, from Observation-Driven Simulations of the Terrestrial Hydrologic Cycle” [Abstract]

Shindell & Faluvegi (2009) “Climate response to regional radiative forcing during the twentieth century” [Abstract] [Full text]

Siegenthaler et al. (2005) “Stable Carbon Cycle–Climate Relationship During the Late Pleistocene” [Abstract] [Full text]

Sitch et al. (2007) “Indirect radiative forcing of climate change through ozone effects on the land-carbon sink” [Abstract] [Full text]

Sokolov et al. (2009) “Probabilistic Forecast for Twenty-First-Century Climate Based on Uncertainties in Emissions (Without Policy) and Climate Parameters” [Abstract] [Full text]

Solomon et al. (2009) “Irreversible climate change due to carbon dioxide emissions” [Abstract] [Full text]

Soon & Baliunas (2003) “Proxy climatic and environmental changes of the past 1000 years” [Abstract] [Full text]

Stammerjohn et al. (2008) “Trends in Antarctic annual sea ice retreat and advance and their relation to El Niño–Southern Oscillation and Southern Annular Mode variability” [Abstract] [Full text]

Steffen et al. (2008) “Rapid Changes in Glaciers and Ice Sheets and Their Impacts on Sea Level” (a report chapter) [Abstract] [Full text]

Steig et al. (2009) “Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year” [Abstract] [Full text]

Stott et al. (2008) “Detection and attribution of Atlantic salinity changes” [Abstract]

Stramma et al. (2008) “Expanding Oxygen-Minimum Zones in the Tropical Oceans” [Abstract] [Full text]

Stroeve et al. (2007) “Arctic sea ice decline: Faster than forecast” [Abstract] [Full text]

Takahashi et al. (2009) “Climatological mean and decadal change in surface ocean pCO2, and net sea–air CO2 flux over the global oceans” [Abstract]

Tarnocai et al. (2009) “Soil organic carbon pools in the northern circumpolar permafrost region” [Abstract] [Full text]

Thompson & Solomon (2002) “Interpretation of Recent Southern Hemisphere Climate Change” [Abstract]

Thorne (2008) “Atmospheric science: The answer is blowing in the wind” [Abstract] [Full text]

Trapp et al. (2007) “Changes in severe thunderstorm environment frequency during the 21st century caused by anthropogenically enhanced global radiative forcing” [Abstract] [Full text]

Trapp et al. (2009) “Transient response of severe thunderstorm forcing to elevated greenhouse gas concentrations” [Abstract] [Full text]

Tripati et al. (2009) “Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years” [Abstract] [Full text]

Turner et al. (2009) “Non‐annular atmospheric circulation change induced by stratospheric ozone depletion and its role in the recent increase of Antarctic sea ice extent” [Abstract]

van den Broeke (2005) “Strong surface melting preceded collapse of Antarctic Peninsula ice shelf” [Abstract] [Full text]

Vecchi et al. (2006) “Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing” [Abstract] [Full text]

Vecchi et al. (2008) “Whither Hurricane Activity?” [Abstract] [Full text]

Velicogna & Wahr (2006) “Acceleration of Greenland ice mass loss in spring 2004” [Abstract]

Velicogna (2009) “Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE” [Abstract]

Vellinga et al. (2008) “Exploring high-end climate change scenarios for flood protection of the Netherlands” [Full text]

Verona et al. (2009) “The coral reef crisis: The critical importance of <350 ppm CO2 [Abstract] [Full text]

Wahl et al. (2006) “Comment on “Reconstructing Past Climate from Noisy Data”” [Abstract] [Full text]

Wahl & Ammann (2007) “Robustness of the Mann, Bradley, Hughes reconstruction of Northern Hemisphere surface temperatures: Examination of criticisms based on the nature and processing of proxy climate evidence” [Abstract] [Full text]

Wallack & Ramanathan (2009 accepted) “Strategies for Hedging Against Rapid Climate Change” (apparently not published yet)

WBGU – German Advisory Council on Global Change (2006) “The Future Oceans – Warming Up, Rising High, Turning Sour” [Abstract] [Full text]

WBGU – German Advisory Council on Global Change (2009) “Solving the climate dilemma: The budget approach” [Abstract] [Full text]

Weart & Pierrehumbert (2007) “A Saturated Gassy Argument” [Full text]

Wentz et al. (2007) “How Much More Rain Will Global Warming Bring?” [Abstract] [Full text]

Westerling et al. (2006) “Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity” [Abstract] [Full text]

Wild et al. (2007) “Impact of global dimming and brightening on global warming” [Abstract] [Full text]

Wingham et al. (2006) “Mass balance of the Antarctic ice sheet” [Abstract] [Full text]

Wouters et al. (2008) “GRACE observes small-scale mass loss in Greenland” [Abstract]

Yeh et al. (2009) “El Niño in a changing climate” [Abstract]

Yin et al. (2009) “Model projections of rapid sea-level rise on the northeast coast of the United States” [Abstract] [Full text]

Zhang et al. (2007) “Detection of human influence on twentieth-century precipitation trends” [Abstract] [Full text]

Zickfeld et al. (2009) “Setting cumulative emissions targets to reduce the risk of dangerous climate change” [Abstract] [Full text]

Zimov et al. (2006) “Permafrost and the Global Carbon Budget” [Abstract] [Full text]


Posted in AGW evidence | 4 Comments »

Papers on polar ice sheets

Posted by Ari Jokimäki on November 24, 2009

This is a list of papers on the modern observations of Greenland and Antarctic ice sheets. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

UPDATE (December 9, 2009): van den Broeke et al. (2009) added.
UPDATE (November 25, 2009): Chen et al. (2009) added, thanks to John Cook for pointing it out, see the comment section below.

Polar ice sheets

Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE – Velicogna (2009) “We use monthly measurements of time-variable gravity from the GRACE (Gravity Recovery and Climate Experiment) satellite gravity mission to determine the ice mass-loss for the Greenland and Antarctic Ice Sheets during the period between April 2002 and February 2009. We find that during this time period the mass loss of the ice sheets is not a constant, but accelerating with time, i.e., that the GRACE observations are better represented by a quadratic trend than by a linear one, implying that the ice sheets contribution to sea level becomes larger with time. In Greenland, the mass loss increased from 137 Gt/yr in 2002–2003 to 286 Gt/yr in 2007–2009, i.e., an acceleration of −30 ± 11 Gt/yr2 in 2002–2009. In Antarctica the mass loss increased from 104 Gt/yr in 2002–2006 to 246 Gt/yr in 2006–2009, i.e., an acceleration of −26 ± 14 Gt/yr2 in 2002–2009.” [Link to PDF]

Recent Sea-Level Contributions of the Antarctic and Greenland Ice Sheets – Shepherd & Wingham (2007) A review article. “As global temperatures have risen, so have rates of snowfall, ice melting, and glacier flow. Although the balance between these opposing processes has varied considerably on a regional scale, data show that Antarctica and Greenland are each losing mass overall. Our best estimate of their combined imbalance is about 125 gigatons per year of ice, enough to raise sea level by 0.35 millimeters per year.” [Link to PDF]

Interannual variations of the mass balance of the Antarctica and Greenland ice sheets from GRACE – Ramillien et al. (2006) “We use new GRACE geoid solutions provided by the Groupe de Recherche en Géodésie Spatiale (GRGS/CNES), at the resolution of ~400 km and sampled at 10-day interval. In the three regions, significant interannual variations are observed, which we approximate as linear trends over the short time span of analysis. Over Greenland, an apparent total volume loss of 119 +/− 10 cu km/yr water is observed. For the Antarctica ice sheet, a bimodal behaviour is apparent, with volume loss amounting to 88 +/− 10 cu km/yr water in the West, and increase in the East amounting to 72 +/− 20 cu km/yr water.” [Link to PDF]

Mass changes of the Greenland and Antarctic ice sheets and shelves and contributions to sea-level rise: 1992-2002 – Zwally et al. (2005) “Changes in ice mass are estimated from elevation changes derived from 10.5 years (Greenland) and 9 years (Antarctica) of satellite radar altimetry data from the European Remote-sensing Satellites ERS-1 and -2. … The Greenland ice sheet is thinning at the margins (−42 ± 2 Gt a−1 below the equilibrium-line altitude (ELA)) and growing inland (+53 ± 2 Gt a−1 above the ELA) with a small overall mass gain (+11 ± 3 Gt a−1; −0.03 mm a−1 SLE (sea-level equivalent)). The ice sheet in West Antarctica (WA) is losing mass (−47 ± 4 Gt a−1) and the ice sheet in East Antarctica (EA) shows a small mass gain (+16 ± 11 Gt a−1) for a combined net change of −31 ± 12 Gt a−1 (+0.08 mm a−1 SLE).” [Link to PDF]

Mass Balance of Polar Ice Sheets – Rignot & Thomas (2002) “Recent advances in the determination of the mass balance of polar ice sheets show that the Greenland Ice Sheet is losing mass by near-coastal thinning, and that the West Antarctic Ice Sheet, with thickening in the west and thinning in the north, is probably thinning overall.” [Link to PDF]

Greenland ice sheet

Partitioning Recent Greenland Mass Loss – van den Broeke et al. (2009) “Mass budget calculations, validated with satellite gravity observations [from the Gravity Recovery and Climate Experiment (GRACE) satellites], enable us to quantify the individual components of recent Greenland mass loss. The total 2000–2008 mass loss of ~1500 gigatons, equivalent to 0.46 millimeters per year of global sea level rise, is equally split between surface processes (runoff and precipitation) and ice dynamics.” [Link to PDF]

Large and Rapid Melt-Induced Velocity Changes in the Ablation Zone of the Greenland Ice Sheet – van de Wal et al. (2008) “Continuous Global Positioning System observations reveal rapid and large ice velocity fluctuations in the western ablation zone of the Greenland Ice Sheet. Within days, ice velocity reacts to increased meltwater production and increases by a factor of 4. Such a response is much stronger and much faster than previously reported. Over a longer period of 17 years, annual ice velocities have decreased slightly, which suggests that the englacial hydraulic system adjusts constantly to the variable meltwater input, which results in a more or less constant ice flux over the years.” [Link to PDF]

Seasonal Speedup Along the Western Flank of the Greenland Ice Sheet – Joughin et al. (2008) “It has been widely hypothesized that a warmer climate in Greenland would increase the volume of lubricating surface meltwater reaching the ice-bedrock interface, accelerating ice flow and increasing mass loss. We have assembled a data set that provides a synoptic-scale view, spanning ice-sheet to outlet-glacier flow, with which to evaluate this hypothesis. On the ice sheet, these data reveal summer speedups (50 to 100%) consistent with, but somewhat larger than, earlier observations. The relative speedup of outlet glaciers, however, is far smaller (<15%). Furthermore, the dominant seasonal influence on Jakobshavn Isbrae's flow is the calving front's annual advance and retreat. With other effects producing outlet-glacier speedups an order of magnitude larger, seasonal melt's influence on ice flow is likely confined to those regions dominated by ice-sheet flow."

Changes in the Velocity Structure of the Greenland Ice Sheet – Rignot & Kanagaratnam (2006) “Using satellite radar interferometry observations of Greenland, we detected widespread glacier acceleration below 66° north between 1996 and 2000, which rapidly expanded to 70° north in 2005. Accelerated ice discharge in the west and particularly in the east doubled the ice sheet mass deficit in the last decade from 90 to 220 cubic kilometers per year. As more glaciers accelerate farther north, the contribution of Greenland to sea-level rise will continue to increase.”

Satellite Gravity Measurements Confirm Accelerated Melting of Greenland Ice Sheet – Chen et al. (2006) “Using time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) satellite mission, we estimate ice mass changes over Greenland during the period April 2002 to November 2005. After correcting for the effects of spatial filtering and limited resolution of GRACE data, the estimated total ice melting rate over Greenland is –239 ± 23 cubic kilometers per year, mostly from East Greenland. This estimate agrees remarkably well with a recent assessment of –224 ± 41 cubic kilometers per year, based on satellite radar interferometry data. GRACE estimates in southeast Greenland suggest accelerated melting since the summer of 2004, consistent with the latest remote sensing measurements.” [Link to PDF]

Surface Melt-Induced Acceleration of Greenland Ice-Sheet Flow – Zwally et al. (2002) “The near coincidence of the ice acceleration with the duration of surface melting, followed by deceleration after the melting ceases, indicates that glacial sliding is enhanced by rapid migration of surface meltwater to the ice-bedrock interface. … The indicated coupling between surface melting and ice-sheet flow provides a mechanism for rapid, large-scale, dynamic responses of ice sheets to climate warming.” [Link to PDF]

Antarctic ice sheet

Accelerated Antarctic ice loss from satellite gravity measurements – Chen et al. (2009) “The Gravity Recovery and Climate Experiment5 (GRACE) offers the opportunity of quantifying polar ice-sheet mass balance from a different perspective6, 7. Here we use an extended record of GRACE data spanning the period April 2002 to January 2009 to quantify the rates of Antarctic ice loss. In agreement with an independent earlier assessment4, we estimate a total loss of 190±77 Gt yr-1, with 132±26 Gt yr-1 coming from West Antarctica. However, in contrast with previous GRACE estimates, our data suggest that East Antarctica is losing mass, mostly in coastal regions, at a rate of -57±52 Gt yr-1, apparently caused by increased ice loss since the year 2006.”

West Antarctic Ice Sheet collapse – the fall and rise of a paradigm – Vaughan (2008) “It is now almost 30 years since John Mercer (1978) first presented the idea that climate change could eventually cause a rapid deglaciation, or “collapse,” of a large part of the West Antarctic ice sheet (WAIS), raising world sea levels by 5 m and causing untold economic and social impacts. This idea, apparently simple and scientifically plausible, created a vision of the future, sufficiently alarming that it became a paradigm for a generation of researchers and provided an icon for the green movement. Through the 1990s, however, a lack of observational evidence for ongoing retreat in WAIS and improved understanding of the complex dynamics of ice streams meant that estimates of likelihood of collapse seemed to be diminishing. In the last few years, however, satellite studies over the relatively inaccessible Amundsen Sea sector of West Antarctica have shown clear evidence of ice sheet retreat showing all the features that might have been predicted for emergent collapse. These studies are re-invigorating the paradigm, albeit in a modified form, and debate about the future stability of WAIS. Since much of WAIS appears to be unchanging, it may, no longer be reasonable to suggest there is an imminent threat of a 5-m rise in sea level resulting from complete collapse of the West Antarctic ice sheet, but there is strong evidence that the Amundsen Sea embayment is changing rapidly. This area alone, contains the potential to raise sea level by around ~1.5 m, but more importantly it seems likely that it could, alter rapidly enough, to make a significant addition to the rate of sea-level rise over coming two centuries. Furthermore, a plausible connection between contemporary climate change and the fate of the ice sheet appears to be developing. The return of the paradigm presents a dilemma for policy-makers, and establishes a renewed set of priorities for the glaciological community. In particular, we must establish whether the hypothesized instability in WAIS is real, or simply an oversimplification resulting from inadequate understanding of the feedbacks that allow ice sheets to achieve equilibrium: and whether there is any likelihood that contemporary climate change could initiate collapse.” David G. Vaughan, Climatic Change, Volume 91, Numbers 1-2, 65-79, DOI: 10.1007/s10584-008-9448-3 [Full text]

Measurements of Time-Variable Gravity Show Mass Loss in Antarctica – Velicogna & Wahr (2006) “Using measurements of time-variable gravity from the Gravity Recovery and Climate Experiment satellites, we determined mass variations of the Antarctic ice sheet during 2002–2005. We found that the mass of the ice sheet decreased significantly, at a rate of 152 ± 80 cubic kilometers of ice per year, which is equivalent to 0.4 ± 0.2 millimeters of global sea-level rise per year. Most of this mass loss came from the West Antarctic Ice Sheet.” [Link to PDF]

Mass balance of the Antarctic ice sheet – Wingham et al. (2006) “Here, we use satellite radar altimetry to measure the elevation change of 72% of the grounded ice sheet during the period 1992–2003. Depending on the density of the snow giving rise to the observed elevation fluctuations, the ice sheet mass trend falls in the range −5-+85 Gt yr−1. … Mass gains from accumulating snow, particularly on the Antarctic Peninsula and within East Antarctica, exceed the ice dynamic mass loss from West Antarctica.” [Link to PDF]

Widespread Complex Flow in the Interior of the Antarctic Ice Sheet – Bamber et al. (2000) “It has been suggested that as much as 90% of the discharge from the Antarctic Ice Sheet is drained through a small number of fast-moving ice streams and outlet glaciers fed by relatively stable and inactive catchment areas. Here, evidence obtained from balance velocity estimates suggests that each major drainage basin is fed by complex systems of tributaries that penetrate up to 1000 kilometers from the grounding line into the interior of the ice sheet.” [Link to PDF]

Satellite Radar Interferometry for Monitoring Ice Sheet Motion: Application to an Antarctic Ice Stream – Goldstein et al. (1993) “The SRI velocities and grounding line of the Rutford Ice Stream, Antarctica, agree fairly well with earlier ground-based data. The combined use of SRI and other satellite methods is expected to provide data that will enhance the understanding of ice stream mechanics and help make possible the prediction of ice sheet behavior.” [Link to PDF]

West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster – Mercer (1978) Not an observational paper but is included here because it seems to be a classic on this subject. “If the global consumption of fossil fuels continues to grow at its present rate, atmospheric CO2 content will double in about 50 years. Climatic models suggest that the resultant greenhouse-warming effect will be greatly magnified in high latitudes. The computed temperature rise at lat 80° S could start rapid deglaciation of West Antarctica, leading to a 5 m rise in sea level.” [Link to PDF]

Posted in AGW evidence | 5 Comments »

Papers on reconstructions of modern temperatures

Posted by Ari Jokimäki on November 17, 2009

This is a list of papers on proxy based reconstructions of modern temperatures with emphasis on global and hemispheric analyses. “Modern” here refers to last few thousands of years. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

UPDATES: December 22, 2021: Osman et al. (2021) and Bova et al. (2021) added. August 1, 2019: Neukom et al. (2019), PAGES 2k Consortium (2019), and Brönnimann et al. (2019) added. Thanks to Barry for pointing them out. February 4, 2017: Hakim et al. (2016) added. Thanks to Barry for pointing it out. November 4, 2015: Marcott et al. (2013), Neukom et al. (2014), and Barboza et al. (2014) added. Thanks to Barry for pointing them out. April 5, 2012): Ljungqvist et al. (2012) added. Thanks to Barry for pointing it out. November 26, 2011: Moberg et al. (2008) added. Thanks to Barry for pointing it out, see the comment section below. Also added were Mann et al. (2005) and Rutherford et al. (2005). September 21, 2011: Frank et al. (2010) and McIntyre & McKitrick (2005) added. Thanks to Barry for pointing them out, see the comment section below. September 20, 2011: D’Arrigo et al. (2006) and Kaufman et al. (2009) added. Thanks to Barry for pointing them out, see the comment section below. March 26, 2011: McShane & Wyner (2011) added. Thanks to Barry for pointing it out, see the comment section below.

Globally resolved surface temperatures since the Last Glacial Maximum – Osman et al. (2021)
Abstract: Climate changes across the past 24,000 years provide key insights into Earth system responses to external forcing. Climate model simulations and proxy data have independently allowed for study of this crucial interval; however, they have at times yielded disparate conclusions. Here, we leverage both types of information using paleoclimate data assimilation to produce the first proxy-constrained, full-field reanalysis of surface temperature change spanning the Last Glacial Maximum to present at 200-year resolution. We demonstrate that temperature variability across the past 24 thousand years was linked to two primary climatic mechanisms: radiative forcing from ice sheets and greenhouse gases; and a superposition of changes in the ocean overturning circulation and seasonal insolation. In contrast with previous proxy-based reconstructions our results show that global mean temperature has slightly but steadily warmed, by ~0.5 °C, since the early Holocene (around 9 thousand years ago). When compared with recent temperature changes, our reanalysis indicates that both the rate and magnitude of modern warming are unusual relative to the changes of the past 24 thousand years.
Citation: Osman, M.B., Tierney, J.E., Zhu, J. et al. Globally resolved surface temperatures since the Last Glacial Maximum. Nature 599, 239–244 (2021).

Seasonal origin of the thermal maxima at the Holocene and the last interglacial – Bova et al. (2021)
Abstract: Proxy reconstructions from marine sediment cores indicate peak temperatures in the first half of the last and current interglacial periods (the thermal maxima of the Holocene epoch, 10,000 to 6,000 years ago, and the last interglacial period, 128,000 to 123,000 years ago) that arguably exceed modern warmth. By contrast, climate models simulate monotonic warming throughout both periods. This substantial model–data discrepancy undermines confidence in both proxy reconstructions and climate models, and inhibits a mechanistic understanding of recent climate change. Here we show that previous global reconstructions of temperature in the Holocene and the last interglacial period reflect the evolution of seasonal, rather than annual, temperatures and we develop a method of transforming them to mean annual temperatures. We further demonstrate that global mean annual sea surface temperatures have been steadily increasing since the start of the Holocene (about 12,000 years ago), first in response to retreating ice sheets (12 to 6.5 thousand years ago), and then as a result of rising greenhouse gas concentrations (0.25 ± 0.21 degrees Celsius over the past 6,500 years or so). However, mean annual temperatures during the last interglacial period were stable and warmer than estimates of temperatures during the Holocene, and we attribute this to the near-constant greenhouse gas levels and the reduced extent of ice sheets. We therefore argue that the climate of the Holocene differed from that of the last interglacial period in two ways: first, larger remnant glacial ice sheets acted to cool the early Holocene, and second, rising greenhouse gas levels in the late Holocene warmed the planet. Furthermore, our reconstructions demonstrate that the modern global temperature has exceeded annual levels over the past 12,000 years and probably approaches the warmth of the last interglacial period (128,000 to 115,000 years ago).
Citation: Bova, S., Rosenthal, Y., Liu, Z. et al. Seasonal origin of the thermal maxima at the Holocene and the last interglacial. Nature 589, 548–553 (2021).

Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era – PAGES 2k Consortium (2019)
Abstract: Multidecadal surface temperature changes may be forced by natural as well as anthropogenic factors, or arise unforced from the climate system. Distinguishing these factors is essential for estimating sensitivity to multiple climatic forcings and the amplitude of the unforced variability. Here we present 2,000-year-long global mean temperature reconstructions using seven different statistical methods that draw from a global collection of temperature-sensitive palaeoclimate records. Our reconstructions display synchronous multidecadal temperature fluctuations that are coherent with one another and with fully forced millennial model simulations from the Coupled Model Intercomparison Project Phase 5 across the Common Era. A substantial portion of pre-industrial (1300–1800 CE) variability at multidecadal timescales is attributed to volcanic aerosol forcing. Reconstructions and simulations qualitatively agree on the amplitude of the unforced global mean multidecadal temperature variability, thereby increasing confidence in future projections of climate change on these timescales. The largest warming trends at timescales of 20 years and longer occur during the second half of the twentieth century, highlighting the unusual character of the warming in recent decades.
Citation: PAGES 2k Consortium (2019). Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era. Nature Geoscience 12, 643–649. doi: 10.1038/s41561-019-0400-0.

Last phase of the Little Ice Age forced by volcanic eruptions – Brönnimann et al. (2019)
Abstract: During the first half of the nineteenth century, several large tropical volcanic eruptions occurred within less than three decades. The global climate effects of the 1815 Tambora eruption have been investigated, but those of an eruption in 1808 or 1809 whose source is unknown and the eruptions in the 1820s and 1830s have received less attention. Here we analyse the effect of the sequence of eruptions in observations, global three-dimensional climate field reconstructions and coupled climate model simulations. All the eruptions were followed by substantial drops of summer temperature over the Northern Hemisphere land areas. In addition to the direct radiative effect, which lasts 2–3 years, the simulated ocean–atmosphere heat exchange sustained cooling for several years after these eruptions, which affected the slow components of the climate system. Africa was hit by two decades of drought, global monsoons weakened and the tracks of low-pressure systems over the North Atlantic moved south. The low temperatures and increased precipitation in Europe triggered the last phase of the advance of Alpine glaciers. Only after the 1850s did the transition into the period of anthropogenic warming start. We conclude that the end of the Little Ice Age was marked by the recovery from a sequence of volcanic eruptions, which makes it difficult to define a single pre-industrial baseline.
Citation: Stefan Brönnimann, Jörg Franke, Samuel U. Nussbaumer, Heinz J. Zumbühl, Daniel Steiner, Mathias Trachsel, Gabriele C. Hegerl, Andrew Schurer, Matthias Worni, Abdul Malik, Julian Flückiger, Christoph C. Raible (2019). Last phase of the Little Ice Age forced by volcanic eruptions. Nature Geoscience 12, 650–656. doi: 10.1038/s41561-019-0402-y.

No evidence for globally coherent warm and cold periods over the preindustrial Common Era – Neukom et al. (2019)
Abstract: Earth’s climate history is often understood by breaking it down into constituent climatic epochs. Over the Common Era (the past 2,000 years) these epochs, such as the Little Ice Age, have been characterized as having occurred at the same time across extensive spatial scales. Although the rapid global warming seen in observations over the past 150 years does show nearly global coherence, the spatiotemporal coherence of climate epochs earlier in the Common Era has yet to be robustly tested. Here we use global palaeoclimate reconstructions for the past 2,000 years, and find no evidence for preindustrial globally coherent cold and warm epochs. In particular, we find that the coldest epoch of the last millennium—the putative Little Ice Age—is most likely to have experienced the coldest temperatures during the fifteenth century in the central and eastern Pacific Ocean, during the seventeenth century in northwestern Europe and southeastern North America, and during the mid-nineteenth century over most of the remaining regions. Furthermore, the spatial coherence that does exist over the preindustrial Common Era is consistent with the spatial coherence of stochastic climatic variability. This lack of spatiotemporal coherence indicates that preindustrial forcing was not sufficient to produce globally synchronous extreme temperatures at multidecadal and centennial timescales. By contrast, we find that the warmest period of the past two millennia occurred during the twentieth century for more than 98 per cent of the globe. This provides strong evidence that anthropogenic global warming is not only unparalleled in terms of absolute temperatures5, but also unprecedented in spatial consistency within the context of the past 2,000 years.
Citation: Raphael Neukom, Nathan Steiger, Juan José Gómez-Navarro, Jianghao Wang, Johannes P. Werner (2019). No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature 571, 550–554. doi: 10.1038/s41586-019-1401-2.

The last millennium climate reanalysis project: Framework and first results – Hakim et al. (2016) “An “offline” approach to DA is used, where static ensemble samples are drawn from existing CMIP climate-model simulations to serve as the prior estimate of climate variables. We use linear, univariate forward models (“proxy system models (PSMs)”) that map climate variables to proxy measurements by fitting proxy data to 2 m air temperature from gridded instrumental temperature data; the linear PSMs are then used to predict proxy values from the prior estimate. Results for the LMR are compared against six gridded instrumental temperature data sets and 25% of the proxy records are withheld from assimilation for independent verification. Results show broad agreement with previous reconstructions of Northern Hemisphere mean 2 m air temperature, with millennial-scale cooling, a multicentennial warm period around 1000 C.E., and a cold period coincident with the Little Ice Age (circa 1450–1800 C.E.). Verification against gridded instrumental data sets during 1880–2000 C.E. reveals greatest skill in the tropics and lowest skill over Northern Hemisphere land areas. Verification against independent proxy records indicates substantial improvement relative to the model (prior) data without proxy assimilation. As an illustrative example, we present multivariate reconstructed fields for a singular event, the 1808/1809 “mystery” volcanic eruption, which reveal global cooling that is strongly enhanced locally due to the presence of the Pacific-North America wave pattern in the 500 hPa geopotential height field.” Hakim, G. J., J. Emile-Geay, E. J. Steig, D. Noone, D. M. Anderson, R. Tardif, N. Steiger, and W. A. Perkins (2016), The last millennium climate reanalysis project: Framework and first results, J. Geophys. Res. Atmos., 121, 6745–6764, doi:10.1002/2016JD024751. [Full text]

Inter-hemispheric temperature variability over the past millennium – Neukom et al. (2014) “The Earth’s climate system is driven by a complex interplay of internal chaotic dynamics and natural and anthropogenic external forcing. Recent instrumental data have shown a remarkable degree of asynchronicity between Northern Hemisphere and Southern Hemisphere temperature fluctuations, thereby questioning the relative importance of internal versus external drivers of past as well as future climate variability. However, large-scale temperature reconstructions for the past millennium have focused on the Northern Hemisphere, limiting empirical assessments of inter-hemispheric variability on multi-decadal to centennial timescales. Here, we introduce a new millennial ensemble reconstruction of annually resolved temperature variations for the Southern Hemisphere based on an unprecedented network of terrestrial and oceanic palaeoclimate proxy records. In conjunction with an independent Northern Hemisphere temperature reconstruction ensemble, this record reveals an extended cold period (1594–1677) in both hemispheres but no globally coherent warm phase during the pre-industrial (1000–1850) era. The current (post-1974) warm phase is the only period of the past millennium where both hemispheres are likely to have experienced contemporaneous warm extremes. Our analysis of inter-hemispheric temperature variability in an ensemble of climate model simulations for the past millennium suggests that models tend to overemphasize Northern Hemisphere–Southern Hemisphere synchronicity by underestimating the role of internal ocean–atmosphere dynamics, particularly in the ocean-dominated Southern Hemisphere. Our results imply that climate system predictability on decadal to century timescales may be lower than expected based on assessments of external climate forcing and Northern Hemisphere temperature variations alone.” Raphael Neukom, Joëlle Gergis, David J. Karoly, Heinz Wanner, Mark Curran, Julie Elbert, Fidel González-Rouco, Braddock K. Linsley, Andrew D. Moy, Ignacio Mundo, Christoph C. Raible, Eric J. Steig, Tas van Ommen, Tessa Vance, Ricardo Villalba, Jens Zinke & David Frank, Nature Climate Change, 4, 362–367 (2014), doi:10.1038/nclimate2174. [Full text]

Reconstructing past temperatures from natural proxies and estimated climate forcings using short- and long-memory models – Barboza et al. (2014) “We produce new reconstructions of Northern Hemisphere annually averaged temperature anomalies back to 1000 AD, and explore the effects of including external climate forcings within the reconstruction and of accounting for short-memory and long-memory features. Our reconstructions are based on two linear models, with the first linking the latent temperature series to three main external forcings (solar irradiance, greenhouse gas concentration and volcanism), and the second linking the observed temperature proxy data (tree rings, sediment record, ice cores, etc.) to the unobserved temperature series. Uncertainty is captured with additive noise, and a rigorous statistical investigation of the correlation structure in the regression errors is conducted through systematic comparisons between reconstructions that assume no memory, short-memory autoregressive models, and long-memory fractional Gaussian noise models. We use Bayesian estimation to fit the model parameters and to perform separate reconstructions of land-only and combined land-and-marine temperature anomalies. For model formulations that include forcings, both exploratory and Bayesian data analysis provide evidence against models with no memory. Model assessments indicate that models with no memory underestimate uncertainty. However, no single line of evidence is sufficient to favor short-memory models over long-memory ones, or to favor the opposite choice. When forcings are not included, the long-memory models appear to be necessary. While including external climate forcings substantially improves the reconstruction, accurate reconstructions that exclude these forcings are vital for testing the fidelity of climate models used for future projections. Finally, we use posterior samples of model parameters to arrive at an estimate of the transient climate response to greenhouse gas forcings of 2.5°C (95% credible interval of [2.16, 2.92]°C), which is on the high end of, but consistent with, the expert-assessment-based uncertainties given in the recent Fifth Assessment Report of the IPCC.” Luis Barboza, Bo Li, Martin P. Tingley, and Frederi G. Viens, Ann. Appl. Stat. Volume 8, Number 4 (2014), 1966-2001. [Full text]

A Reconstruction of Regional and Global Temperature for the Past 11,300 Years – Marcott et al. (2013) “Surface temperature reconstructions of the past 1500 years suggest that recent warming is unprecedented in that time. Here we provide a broader perspective by reconstructing regional and global temperature anomalies for the past 11,300 years from 73 globally distributed records. Early Holocene (10,000 to 5000 years ago) warmth is followed by ~0.7°C cooling through the middle to late Holocene (<5000 years ago), culminating in the coolest temperatures of the Holocene during the Little Ice Age, about 200 years ago. This cooling is largely associated with ~2°C change in the North Atlantic. Current global temperatures of the past decade have not yet exceeded peak interglacial values but are warmer than during ~75% of the Holocene temperature history. Intergovernmental Panel on Climate Change model projections for 2100 exceed the full distribution of Holocene temperature under all plausible greenhouse gas emission scenarios.” Shaun A. Marcott, Jeremy D. Shakun, Peter U. Clark, Alan C. Mix, Science 8 March 2013: Vol. 339 no. 6124 pp. 1198-1201, DOI: 10.1126/science.1228026. [Full text]

Northern Hemisphere temperature patterns in the last 12 centuries – Ljungqvist et al. (2012) “We analyse the spatio-temporal patterns of temperature variability over Northern Hemisphere land areas, on centennial time-scales, for the last 12 centuries using an unprecedentedly large network of temperature-sensitive proxy records. Geographically widespread positive temperature anomalies are observed from the 9th to 11th centuries, similar in extent and magnitude to the 20th century mean. A dominance of widespread negative anomalies is observed from the 16th to 18th centuries. Though we find the amplitude and spatial extent of the 20th century warming is within the range of natural variability over the last 12 centuries, we also find that the rate of warming from the 19th to the 20th century is unprecedented in the context of the last 1200 yr. The positive Northern Hemisphere temperature change from the 19th to the 20th century is clearly the largest between any two consecutive centuries in the past 12 centuries. These results remain robust even after removing a significant number of proxies in various tests of robustness showing that the choice of proxies has no particular influence on the overall conclusions of this study.” Ljungqvist, F. C., Krusic, P. J., Brattström, G., and Sundqvist, H. S.: Northern Hemisphere temperature patterns in the last 12 centuries, Clim. Past, 8, 227-249, doi:10.5194/cp-8-227-2012, 2012. [Full text]

A statistical analysis of multiple temperature proxies: Are reconstructions of surface temperatures over the last 1000 years reliable? – McShane & Wyner (2011) “Predicting historic temperatures based on tree rings, ice cores, and other natural proxies is a difficult endeavor. The relationship between proxies and temperature is weak and the number of proxies is far larger than the number of target data points. Furthermore, the data contain complex spatial and temporal dependence structures which are not easily captured with simple models. In this paper, we assess the reliability of such reconstructions and their statistical significance against various null models. We find that the proxies do not predict temperature significantly better than random series generated independently of temperature. Furthermore, various model specifications that perform similarly at predicting temperature produce extremely different historical backcasts. Finally, the proxies seem unable to forecast the high levels of and sharp run-up in temperature in the 1990s either in-sample or from contiguous holdout blocks, thus casting doubt on their ability to predict such phenomena if in fact they occurred several hundred years ago. We propose our own reconstruction of Northern Hemisphere average annual land temperature over the last millennium, assess its reliability, and compare it to those from the climate science literature. Our model provides a similar reconstruction but has much wider standard errors, reflecting the weak signal and large uncertainty encountered in this setting.” [Full text], [Discussion papers on this]

A noodle, hockey stick, and spaghetti plate: a perspective on high-resolution paleoclimatology – Frank et al. (2010) “The high-resolution reconstruction of hemispheric-scale temperature variation over the past-millennium benchmarks recent warming against more naturally driven climate episodes, such as the Little Ice Age and the Medieval Warm Period, thereby allowing assessment of the relative efficacies of natural and anthropogenic forcing factors. Icons of past temperature variability, as featured in the Intergovernmental Panel on Climate Change (IPCC) reports over nearly two decades, have changed from a schematic sketch in 1990, to a seemingly well-solved story in 2001, to more explicit recognition of significant uncertainties in 2007. In this article, we detail the beginning of the movement to reconstruct large-scale temperatures, highlight major steps forward, and present our views on what remains to be accomplished. Despite significant efforts and progress, the spatial representation of reconstructions is limited, and the interannual and centennial variation are poorly quantified. Research priorities to reduce reconstruction uncertainties and improve future projections, include (1) increasing the role of expert assessment in selecting and incorporating the highest quality proxy data in reconstructions (2) employing reconstruction ensemble methodology, and (3) further improvements of forcing series. We suggest that much of the sensitivity in the reconstructions, a topic that has dominated scientific debates, can be traced back to the input data. It is perhaps advisable to use fewer, but expert-assessed proxy records to reduce errors in future reconstruction efforts.” David Frank, Jan Esper, Eduardo Zorita, Rob Wilson, Wiley Interdisciplinary Reviews: Climate Change, Volume 1, Issue 4, pages 507–516, July/August 2010. [Full text]

Recent Warming Reverses Long-Term Arctic Cooling – Kaufman et al. (2009) “The temperature history of the first millennium C.E. is sparsely documented, especially in the Arctic. We present a synthesis of decadally resolved proxy temperature records from poleward of 60°N covering the past 2000 years, which indicates that a pervasive cooling in progress 2000 years ago continued through the Middle Ages and into the Little Ice Age. A 2000-year transient climate simulation with the Community Climate System Model shows the same temperature sensitivity to changes in insolation as does our proxy reconstruction, supporting the inference that this long-term trend was caused by the steady orbitally driven reduction in summer insolation. The cooling trend was reversed during the 20th century, with four of the five warmest decades of our 2000-year-long reconstruction occurring between 1950 and 2000.” Darrell S. Kaufman, David P. Schneider, Nicholas P. McKay, Caspar M. Ammann, Raymond S. Bradley, Keith R. Briffa, Gifford H. Miller, Bette L. Otto-Bliesner, Jonathan T. Overpeck, Bo M. Vinther and Arctic Lakes 2k Project Members, Science 4 September 2009: Vol. 325 no. 5945 pp. 1236-1239, DOI: 10.1126/science.1173983. [Full text]

Analysis of the Moberg et al. (2005) hemispheric temperature reconstruction – Moberg et al. (2008) “The Moberg et al. (Nature 433(7026):613–617, 2005. doi:10.1038/nature03265; M05) reconstruction of northern hemisphere temperature variations from proxy data has been criticised; the M05 method may artificially inflate low-frequency variance relative to reality. We test this assertion by undertaking several pseudoproxy experiments in three climate model simulations—one control run and two forced simulations that include several time-varying radiative forcings. The pseudoproxy series are designed to have the same variance spectra as the real M05 proxies, primarily to mimic the low-resolution character of several series. A simple composite-plus-scale (CPS) method is also analysed. In the CPS case all input data behave like annually resolved proxies. The spectral domain performance of both M05 and CPS is found to be dependent on the noise type and noise level in pseudoproxies, on the variance spectrum of the climate model simulation, and on the degree of data smoothing. CPS performs better than M05 in most investigated cases with the control run, but leads to deflated low-frequency variance in some cases. With M05, low-frequency variance tend to be inflated for the control run but not for one of the forced runs and only very slightly with the other forced simulation. Hence, the M05 approach does not routinely inflate low-frequency variance. In our experiment, the M05 approach performs better in the spectral domain than CPS when applied to forced climate model simulations. The results underscore the importance of evaluating the variance spectrum of climate reconstructions.” Anders Moberg, Rezwan Mohammad and Thorsten Mauritsen, Climate Dynamics, Volume 31, Numbers 7-8, 957-971, DOI: 10.1007/s00382-008-0392-8.

On the reliability of millennial reconstructions of variations in surface air temperature in the Northern Hemisphere – Datsenko & Sonechkin (2008) “The reliability of the recently published reconstructions of the surface air temperature variability in the Northern Hemisphere over the past 2000 yr is discussed. For this purpose, the power spectra of the two best known reconstructions (Mann et al.[10–12] and Moberg et al. [13]) are calculated and compared to the spectra of the 150-yr temperature series based on instrumental observations and simulated 1000-yr series. It is found that the Mann et al. reconstruction drastically underestimates low-frequency temperature variations, whereas the Moberg et al. reconstruction reproduces them much better, although with a certain underestimation rather than overestimation, as Mann et al. have recently argued.”

Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia – Mann et al. (2008) “Following the suggestions of a recent National Research Council report [NRC (National Research Council) (2006) Surface Temperature Reconstructions for the Last 2,000 Years (Natl Acad Press, Washington, DC).], we reconstruct surface temperature at hemispheric and global scale for much of the last 2,000 years using a greatly expanded set of proxy data for decadal-to-centennial climate changes, recently updated instrumental data, and complementary methods that have been thoroughly tested and validated with model simulation experiments. Our results extend previous conclusions that recent Northern Hemisphere surface temperature increases are likely anomalous in a long-term context. Recent warmth appears anomalous for at least the past 1,300 years whether or not tree-ring data are used.” [Full text]

Millennial temperature reconstruction intercomparison and evaluation – Juckes et al. (2007) “Here recent work is reviewed and some new calculations performed with an aim to clarifying the consequences of the different approaches used. A range of proxy data collections introduced by different authors is used to estimate Northern Hemispheric annual mean temperatures with two reconstruction algorithms: (1) inverse regression and, (2) compositing followed by variance matching (CVM). … A reconstruction using 13 proxy records extending back to AD 1000 shows a maximum pre-industrial temperature of 0.25 K (relative to the 1866 to 1970 mean). The standard error on this estimate, based on the residual in the calibration period, is 0.14 K. Instrumental temperatures for two recent years (1998 and 2005) have exceeded the pre-industrial estimated maximum by more than 4 standard deviations of the calibration period residual.” [Link to PDF]

On the long-term context for late twentieth century warming – D’Arrigo et al. (2006) “Previous tree-ring–based Northern Hemisphere temperature reconstructions portray a varying amplitude range between the “Medieval Warm Period” (MWP), “Little Ice Age” (LIA) and present. We describe a new reconstruction, developed using largely different methodologies and additional new data compared to previous efforts. Unlike earlier studies, we quantify differences between more traditional (STD) and Regional Curve Standardization (RCS) methodologies, concluding that RCS is superior for retention of low-frequency trends. Continental North American versus Eurasian RCS series developed prior to merging to the hemispheric scale cohere surprisingly well, suggesting common forcing, although there are notable deviations (e.g., fifteenth to sixteenth century). Results indicate clear MWP (warm), LIA (cool), and recent (warm) episodes. Direct interpretation of the RCS reconstruction suggests that MWP temperatures were nearly 0.7°C cooler than in the late twentieth century, with an amplitude difference of 1.14°C from the coldest (1600–1609) to warmest (1937–1946) decades. However, we advise caution with this analysis. Although we conclude, as found elsewhere, that recent warming has been substantial relative to natural fluctuations of the past millennium, we also note that owing to the spatially heterogeneous nature of the MWP, and its different timing within different regions, present palaeoclimatic methodologies will likely “flatten out” estimates for this period relative to twentieth century warming, which expresses a more homogenous global “fingerprint.” Therefore we stress that presently available paleoclimatic reconstructions are inadequate for making specific inferences, at hemispheric scales, about MWP warmth relative to the present anthropogenic period and that such comparisons can only still be made at the local/regional scale.” D’Arrigo, R., R. Wilson, and G. Jacoby (2006), J. Geophys. Res., 111, D03103, doi:10.1029/2005JD006352. [Full text]

Climate sensitivity constrained by temperature reconstructions over the past seven centuries – Hegerl et al. (2006) “A number of observational studies, however, find a substantial probability of significantly higher sensitivities, yielding upper limits on climate sensitivity of 7.7 K to above 9 K (refs 3–8). Here we demonstrate that such observational estimates of climate sensitivity can be tightened if reconstructions of Northern Hemisphere temperature over the past several centuries are considered. … After accounting for the uncertainty in reconstructions and estimates of past external forcing, we find an independent estimate of climate sensitivity that is very similar to those from instrumental data. If the latter are combined with the result from all proxy reconstructions, then the 5–95 per cent range shrinks to 1.5–6.2 K, thus substantially reducing the probability of very high climate sensitivity.” [Link to PDF]

Testing the Fidelity of Methods Used in Proxy-Based Reconstructions of Past Climate – Mann et al. (2005) “Two widely used statistical approaches to reconstructing past climate histories from climate “proxy” data such as tree rings, corals, and ice cores are investigated using synthetic “pseudoproxy” data derived from a simulation of forced climate changes over the past 1200 yr. These experiments suggest that both statistical approaches should yield reliable reconstructions of the true climate history within estimated uncertainties, given estimates of the signal and noise attributes of actual proxy data networks.” Mann, Michael E., Scott Rutherford, Eugene Wahl, Caspar Ammann, 2005, J. Climate, 18, 4097–4107, doi: [Full text]

Extracting a Climate Signal from 169 Glacier Records – Oerlemans et al. (2005) “I constructed a temperature history for different parts of the world from 169 glacier length records. Using a first-order theory of glacier dynamics, I related changes in glacier length to changes in temperature. … Moderate global warming started in the middle of the 19th century. The reconstructed warming in the first half of the 20th century is 0.5 kelvin.” [Link to PDF]

Proxy-Based Northern Hemisphere Surface Temperature Reconstructions: Sensitivity to Method, Predictor Network, Target Season, and Target Domain – Rutherford et al. (2005) “Results are presented from a set of experiments designed to investigate factors that may influence proxy-based reconstructions of large-scale temperature patterns in past centuries. The factors investigated include 1) the method used to assimilate proxy data into a climate reconstruction, 2) the proxy data network used, 3) the target season, and 4) the spatial domain of the reconstruction. Estimates of hemispheric-mean temperature are formed through spatial averaging of reconstructed temperature patterns that are based on either the local calibration of proxy and instrumental data or a more elaborate multivariate climate field reconstruction approach. The experiments compare results based on the global multiproxy dataset used by Mann and coworkers, with results obtained using the extratropical Northern Hemisphere (NH) maximum latewood tree-ring density set used by Briffa and coworkers. Mean temperature reconstructions are compared for the full NH (Tropics and extratropics, land and ocean) and extratropical continents only, withvarying target seasons (cold-season half year, warm-season half year, and annual mean). The comparisons demonstrate dependence of reconstructions on seasonal, spatial, and methodological considerations, emphasizing the primary importance of the target region and seasonal window of the reconstruction. The comparisons support the generally robust nature of several previously published estimates of NH mean temperature changes in past centuries and suggest that further improvements in reconstructive skill are most likely to arise from an emphasis on the quality, rather than quantity, of available proxy data.” Rutherford, S., M. E. Mann, T. J. Osborn, K. R. Briffa, P D. Jones, R. S. Bradley, M. K. Hughes, 2005, J. Climate, 18, 2308–2329, doi: [Full text]

Hockey sticks, principal components, and spurious significance – McIntyre & McKitrick (2005) “The “hockey stick” shaped temperature reconstruction of Mann et al. (1998, 1999) has been widely applied. However it has not been previously noted in print that, prior to their principal components (PCs) analysis on tree ring networks, they carried out an unusual data transformation which strongly affects the resulting PCs. Their method, when tested on persistent red noise, nearly always produces a hockey stick shaped first principal component (PC1) and overstates the first eigenvalue. In the controversial 15th century period, the MBH98 method effectively selects only one species (bristlecone pine) into the critical North American PC1, making it implausible to describe it as the “dominant pattern of variance”. Through Monte Carlo analysis, we show that MBH98 benchmarks for significance of the Reduction of Error (RE) statistic are substantially under-stated and, using a range of cross-validation statistics, we show that the MBH98 15th century reconstruction lacks statistical significance.” McIntyre, S., and R. McKitrick (2005), Geophys. Res. Lett., 32, L03710, doi:10.1029/2004GL021750. [Full text]

Proxy-Based Northern Hemisphere Surface Temperature Reconstructions: Sensitivity to Method, Predictor Network, Target Season, and Target Domain – Rutherford et al. (2005) “Results are presented from a set of experiments designed to investigate factors that may influence proxy-based reconstructions of large-scale temperature patterns in past centuries. … The comparisons demonstrate dependence of reconstructions on seasonal, spatial, and methodological considerations, emphasizing the primary importance of the target region and seasonal window of the reconstruction.” [Link to PDF]

Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data – Moberg et al. (2005) “Here we reconstruct Northern Hemisphere temperatures for the past 2,000 years by combining low-resolution proxies with tree-ring data, using a wavelet transform technique11 to achieve timescale-dependent processing of the data. … According to our reconstruction, high temperatures—similar to those observed in the twentieth century before 1990—occurred around ad 1000 to 1100, and minimum temperatures that are about 0.7 K below the average of 1961–90 occurred around ad 1600.” [Link to PDF] [Their own 2008-paper that criticises this work]

Borehole climate reconstructions: Spatial structure and hemispheric averages – Pollack & Smerdon (2004) “Ground surface temperature (GST) reconstructions determined from temperature profiles measured in terrestrial boreholes, when averaged over the Northern Hemisphere, estimate a surface warming of ∼1 K during the interval AD 1500–2000. Other traditional proxy-based estimates suggest less warming during the same interval. … We demonstrate the consistency of GST warming estimates by showing that over a wide range of grid element area and occupancy weighting schemes, the five-century GST change falls in the range of 0.89–1.05 K. … Reconstructions assembled after excluding low-occupancy grid elements show a five-century GST change in the range of 1.02–1.06 K.” [Link to PDF]

Climate over past millennia – Jones & Mann (2004) “We review evidence for climate change over the past several millennia from instrumental and high-resolution climate “proxy” data sources and climate modeling studies. … We devote particular attention to proxy-based reconstructions of temperature patterns in past centuries, which place recent large-scale warming in an appropriate longer-term context. Our assessment affirms the conclusion that late 20th century warmth is unprecedented at hemispheric and, likely, global scales.” [Link to PDF]

Global surface temperatures over the past two millennia – Mann & Jones (2003) “We present reconstructions of Northern and Southern Hemisphere mean surface temperature over the past two millennia based on high-resolution ‘proxy’ temperature data which retain millennial-scale variability. These reconstructions indicate that late 20th century warmth is unprecedented for at least roughly the past two millennia for the Northern Hemisphere.” [Link to PDF]

Low-frequency temperature variations from a northern tree ring density network – Briffa et al. (2001) “We describe new reconstructions of northern extratropical summer temperatures for nine subcontinental-scale regions and a composite series representing quasi “Northern Hemisphere” temperature change over the last 600 years. … The 20th century is clearly shown by all of the palaeoseries composites to be the warmest during this period.” [Link to PDF]

Temperature trends over the past five centuries reconstructed from borehole temperatures – Huang et al. (2000) “Here we use present-day temperatures in 616 boreholes from all continents except Antarctica to reconstruct century-long trends in temperatures over the past 500 years at global, hemispheric and continental scales. The results confirm the unusual warming of the twentieth century revealed by the instrumental record6, but suggest that the cumulative change over the past five centuries amounts to about 1 K, exceeding recent estimates from conventional climate proxies.” [Link to PDF]

Annual climate variability in the Holocene: interpreting the message of ancient trees – Briffa (2000) “As for assessing the significance of 20th century global warming, the evidence from dendroclimatology in general, supports the notion that the last 100 years have been unusually warm, at least within a context of the last two millennia. However, this evidence should not be considered equivocal. The activities of humans may well be impacting on the ‘natural’ growth of trees in different ways, making the task of isolating a clear climate message subtly difficult.” [Link to PDF]

Northern hemisphere temperatures during the past millennium: Inferences, uncertainties, and limitations – Mann et al. (1999) “Building on recent studies, we attempt hemispheric temperature reconstructions with proxy data networks for the past millennium. We focus not just on the reconstructions, but the uncertainties therein, and important caveats. Though expanded uncertainties prevent decisive conclusions for the period prior to AD 1400, our results suggest that the latter 20th century is anomalous in the context of at least the past millennium. The 1990s was the warmest decade, and 1998 the warmest year, at moderately high levels of confidence. The 20th century warming counters a millennial‐scale cooling trend which is consistent with long‐term astronomical forcing.” [Link to PDF]

Global-scale temperature patterns and climate forcing over the past six centuries – Mann et al. (1998) “Spatially resolved global reconstructions of annual surface temperature patterns over the past six centuries are based on the multivariate calibration of widely distributed high-resolution proxy climate indicators. Time-dependent correlations of the reconstructions with time-series records representing changes in greenhouse-gas concentrations, solar irradiance, and volcanic aerosols suggest that each of these factors has contributed to the climate variability of the past 400 years, with greenhouse gases emerging as the dominant forcing during the twentieth century. Northern Hemisphere mean annual temperatures for three of the past eight years are warmer than any other year since (at least) ad 1400.” [Link to PDF]

High-resolution palaeoclimatic records for the last millennium: interpretation, integration and comparison with General Circulation Model control-run temperatures – Jones et al. (1998) “We have averaged 17 temperature reconstructions (representing various seasons of the year), all extending back at least to the mid-seventeenth century, to form two annually resolved hemispheric series (NH10 and SH7). … The coldest year of the millennium over the NH is ad 1601, the coldest decade 1691–1700 and the seventeenth is the coldest century.” [Link to PDF]

Influence of volcanic eruptions on Northern Hemisphere summer temperature over the past 600 years – Briffa et al. (1998) “Here we use this well dated, high-resolution composite time-series to suggest that large explosive volcanic eruptions produced different extents of Northern Hemisphere cooling during the past 600 years. The large effect of some recent eruptions is apparent, such as in 1816, 1884 and 1912, but the relative effects of other known, and perhaps some previously unknown, pre-nineteenth-century eruptions are also evaluated. The most severe short-term Northern Hemisphere cooling event of the past 600 years occurred in 1601, suggesting that either the effect on climate of the eruption of Huaynaputina, Peru, in 1600 has previously been greatly underestimated, or another, as yet unidentified, eruption occurred at the same time.”

‘Little Ice Age’ summer temperature variations: their nature and relevance to recent global warming trends – Bradley & Jones (1993) “Using historical, tree-ring and ice core data, we examine climatic variations during the period commonly called the ‘Little Ice Age’. The coldest conditions of the last 560 years were between AD 1570 and 1730, and in the nineteenth century. Unusually warm conditions have prevailed since the 1920s, probably related to a relative absence of major explosive volcanic eruptions and higher levels of greenhouse gases.”

Closely related

Papers on the MWP as Global Event

Posted in AGW evidence | 27 Comments »

Papers on the iris hypothesis of Lindzen

Posted by Ari Jokimäki on November 13, 2009

This is a list of papers on the iris hypothesis of Lindzen. The list contains only papers that concentrate on the iris hypothesis, so there’s no such papers that study related matters but only mention the hypothesis in passing. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

UPDATE (November 18, 2009): Earth Observatory article added to the “closely related” section, thanks to Paul Middents for pointing it out (see the comment section below).

Papers of others

An Evaluation of the Proposed Mechanism of the Adaptive Infrared Iris Hypothesis Using TRMM VIRS and PR Measurements – Rapp et al. (2005) “This [iris] hypothesis assumes that increased precipitation efficiency in regions of higher sea surface temperatures will reduce cirrus detrainment. Tropical Rainfall Measuring Mission (TRMM) satellite measurements are used here to investigate the adaptive infrared iris hypothesis. … The current analysis does not show any significant SST dependence of the ratio of cloud area to surface rainfall for deep convection in the tropical western and central Pacific.” [Link to PDF]

Examination of the Decadal Tropical Mean ERBS Nonscanner Radiation Data for the Iris Hypothesis – Lin et al. (2004) “In this study, the ERBS decadal observations are compared with the predictions of the Iris hypothesis using 3.5-box model. … On the decadal time scale, the predicted tropical mean radiative flux anomalies are generally significantly different from those of the ERBS measurements, suggesting that the decadal ERBS nonscanner radiative energy budget measurements do not support the strong negative feedback of the Iris effect.” [Link to PDF]

The decadal tropical mean radiation data and the Iris hypothesis – Lin et al. (2003) A conference paper. “This study examines the evidence of the strong negative climate feedback of the Iris hypothesis using decadal satellite observations of tropical mean radiative energy budget anomalies, and finds that the decadal satellite measurements do not support the Iris effect.”

Examination of New CERES Data for Evidence of Tropical Iris Feedback – Chambers et al. (2002) “New data products from the Clouds and the Earth’s Radiant Energy System (CERES) instrument on the Tropical Rainfall Measuring Mission Satellite have been examined in the context of the recently proposed adaptive tropical infrared Iris hypothesis. … Regardless of definition, the radiative properties are found to be different from those assigned in the original Iris hypothesis. As a result, the strength of the feedback effect is reduced by a factor of 10 or more. Contrary to the initial Iris hypothesis, most of the definitions tested in this paper result in a small positive feedback. Thus, the existence of an effective infrared iris to counter greenhouse warming is not supported by the CERES data.”

New CERES Data Examined for Evidence of Tropical Iris Feedback – Chambers et al. (2002) A conference paper. “New data products are available from the CERES instrument, a part of the NASA Earth Observing System. … Regardless, the current results show that the proposed Iris feedback is very much weaker when objectively-determined radiative properties are used in the model.” [Link to PDF]

Reply – Chambers et al. (2002) “Chou et al. (2002, hereinafter CLH) argue in their comment that the way in which Lin et al. (2002) analyzed the Clouds and the Earth’s Radiant Energy System (CERES) data (Wielicki et al. 1996) is not appropriate. … The analysis in the Lin et al. paper exactly followed the original iris idea, as presented by Lindzen et al. (2001, hereinafter LCH), yet obtained significantly different results. We have repeated the analysis with some additional thresholds as illustrated in the CLH comment, and our basic conclusion remains: the difference between the net radiative fluxes of the cloudy-moist and clear-moist regions should be small. Thus, the radiative forcing resulting from a change in tropical high cloud amount is still about 1/10 of that found in LCH.” [Link to PDF]

Climatic Properties of Tropical Precipitating Convection under Varying Environmental Conditions – Del Genio & Kovari (2002) “A clustering algorithm is used to define the radiative, hydrological, and microphysical properties of precipitating convective events in the equatorial region observed by the Tropical Rainfall Measuring Mission (TRMM) satellite. … The adaptive iris hypothesis (clouds thinning with warming) is clearly not supported by the TRMM data. … Several flaws in reasoning lead Lindzen et al. (2001) to their conclusion.” [Link to PDF]

Tropical cirrus and water vapor: an effective Earth infrared iris feedback? – Fu et al. (2002) “We argue that the water vapor feedback is overestimated in Lindzen et al. (2001) by at least 60%, and that the high cloud feedback is small. Although not mentioned by Lindzen et al. (2001), tropical low clouds make a significant contribution to their negative feedback, which is also overestimated. Using more realistic parameters in the model of Lindzen et al. (2001), we obtain a feedback factor in the range of -0.15 to -0.51, compared to their larger negative feedback factor of -0.45 to -1.03. It is noted that our feedback factor could still be overestimated due to the assumption of constant low cloud cover in the simple radiative-convective model.” [Link to PDF]

The Iris Hypothesis: A Negative or Positive Cloud Feedback? – Lin et al. (2002) “Using the Tropical Rainfall Measuring Mission (TRMM) satellite measurements over tropical oceans, this study evaluates the iris hypothesis recently proposed by Lindzen et al. that tropical upper-tropospheric anvils act as a strong negative feedback in the global climate system. … The observations show that the clouds have much higher albedos and moderately larger longwave fluxes than those assumed by Lindzen et al. As a result, decreases in these clouds would cause a significant but weak positive feedback to the climate system, instead of providing a strong negative feedback.” [Link to PDF]

Comments on “Does the Earth Have an Adaptive Infrared Iris?” – Harrison (2002) Finds much smaller value for fractional cloud-cover decrease per °C than Lindzen et al. (2001). [Link to PDF]

No Evidence for Iris – Hartmann & Michelsen (2002) “It is shown that the negative correlation between cloud-weighted sea surface temperature (SST) and high cloud fraction discussed recently by Lindzen et al. results from variations in subtropical clouds that are not physically connected to the deep convection near the equator. A negative correlation between cloud-weighted SST and average cloud fraction results from any variation in cloud fraction over the areas with lower SSTs within the domain of interest. Therefore, this correlation is not evidence that tropical cloud anvil area is inversely proportional to sea surface temperature and should not be used to infer the existence of a negative feedback in the climate system.” [Link to PDF]

Papers of Lindzen et al.

Comments on “Examination of the Decadal Tropical Mean ERBS Nonscanner Radiation Data for the Iris Hypothesis” – Chou & Lindzen (2005)

Further Results On The Iris Effect – Lindzen et al. (2002) A conference paper. “Our data set now extends to 4 full years rather than the 20 months used in the original study. … We have used CERES data in order to investigate how albedo varies with area of cirrus (scaled by cumulus activity) in order to separate the albedo change due to fluctuations of cirrus areas from mean albedos which are biased by the high albedos associated with thick anvils near cumulus cores. It is, of course, the former which are relevant to the feedback. Results from each of the above studies will be presented.”

Comment on “No Evidence for Iris” – Lindzen et al. (2002) “However, the points raised by HM hardly constitute challenges to the hypothesis.” [Link to PDF]

Comments on “The Iris Hypothesis: A Negative or Positive Cloud Feedback?” – Chou et al. (2002) “The difference in the feedback factor is due to a larger contrast in albedos and a smaller contrast in the outgoing longwave radiation (OLR) between the high-level cloudy region and the surrounding regions as derived by Lin et al. when compared with that specified in LCH. It appears that the approach taken by Lin et al. to estimate the albedo and OLR is not appropriate and that the inferred climate sensitivity is unreliable.” [Link to PDF]

Does the Earth Have an Adaptive Infrared Iris? – Lindzen et al. (2001) “Motivated by the observed relation between cloudiness (above the trade wind boundary layer) and high humidity, cloud data for the eastern part of the western Pacific from the Japanese Geostationary Meteorological Satellite–5 (which provides high spatial and temporal resolution) have been analyzed, and it has been found that the area of cirrus cloud coverage normalized by a measure of the area of cumulus coverage decreases about 22% per degree Celsius increase in the surface temperature of the cloudy region. … This new mechanism would, in effect, constitute an adaptive infrared iris that opens and closes in order to control the Outgoing Longwave Radiation in response to changes in surface temperature in a manner similar to the way in which an eye’s iris opens and closes in response to changing light levels.” [Link to PDF]

Closely related

Earth Observatory: Arbiters of Energy A lay people level review of the issue.

Posted in Climate claims | 2 Comments »

Papers on carbon cycle feedback

Posted by Ari Jokimäki on November 11, 2009

This is a list of papers on carbon cycle feedback. Note that the list is not only observational papers, there are modelling papers also. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

Quantifying Carbon Cycle Feedbacks – Gregory et al. (2009) “This paper demonstrates how carbon cycle feedback can be expressed in formally similar ways to climate feedback, and thus compares their magnitudes. The carbon cycle gives rise to two climate feedback terms: the concentration–carbon feedback, resulting from the uptake of carbon by land and ocean as a biogeochemical response to the atmospheric CO2 concentration, and the climate–carbon feedback, resulting from the effect of climate change on carbon fluxes. In the earth system models of the Coupled Climate–Carbon Cycle Model Intercomparison Project (C4MIP), climate–carbon feedback on warming is positive and of a similar size to the cloud feedback. The concentration–carbon feedback is negative; it has generally received less attention in the literature, but in magnitude it is 4 times larger than the climate–carbon feedback and more uncertain.”

A revised estimate of the processes contributing to global warming due to climate-carbon feedback – Cadule et al. (2009) “We show here that, because of the specific spatial and temporal distribution of the radiative forcing exerted by those external perturbations, the temperature gains are all different. Based on our revised method, we found that, for the SRES A2 scenario, the projected global warming in 2100, due to increases in atmospheric CO2, non-CO2 GHGs and anthropogenic sulphate aerosols, is 2.3–5.6°C. This is accidentally nearly equal to the original one of Meehl et al. (2007) (2.4–5.6°C).”

What determines the magnitude of carbon cycle-climate feedbacks? – Matthews et al. (2007) “In this study, we use a coupled climate-carbon model to investigate how the response of vegetation photosynthesis to climate change contributes to the overall strength of carbon cycle-climate feedbacks. We find that the feedback strength is particularly sensitive to the model representation of the photosynthesis-temperature response, with lesser sensitivity to the parameterization of soil moisture and nitrogen availability. In all simulations, large feedbacks are associated with a climatic suppression of terrestrial primary productivity and consequent reduction of terrestrial carbon uptake.” [Link to PDF]

Terrestrial Carbon–Cycle Feedback to Climate Warming – Luo (2007) A review article. “Nonetheless, experimental results are so variable that we have not generated the necessary insights on ecosystem responses to effectively improve global models. To constrain model projections of carbon-climate feedbacks, we need more empirical data from whole-ecosystem warming experiments across a wide range of biomes, particularly in tropic regions, and closer interactions between models and experiments.” [Link to PDF]

Climate–Carbon Cycle Feedback Analysis: Results from the C4MIP Model Intercomparison – Friedlingstein et al. (2006) “Eleven coupled climate–carbon cycle models used a common protocol to study the coupling between climate change and the carbon cycle. … There was unanimous agreement among the models that future climate change will reduce the efficiency of the earth system to absorb the anthropogenic carbon perturbation. A larger fraction of anthropogenic CO2 will stay airborne if climate change is accounted for. By the end of the twenty-first century, this additional CO2 varied between 20 and 200 ppm for the two extreme models, the majority of the models lying between 50 and 100 ppm. The higher CO2 levels led to an additional climate warming ranging between 0.1° and 1.5°C.” [Link to PDF]

Positive feedback between global warming and atmospheric CO2 concentration inferred from past climate change – Scheffer et al. (2006) “Here we present an alternative way of estimating the magnitude of the feedback effect based on reconstructed past changes. Linking this information with the mid-range Intergovernmental Panel on Climate Change estimation of the greenhouse gas effect on temperature we suggest that the feedback of global temperature on atmospheric CO2 will promote warming by an extra 15–78% on a century-scale.” [Link to PDF]

Primary productivity control of simulated carbon cycle–climate feedbacks – Matthews et al. (2005) “In this study, we demonstrate that the response of vegetation primary productivity to climate changes is a critical controlling factor in determining the strength of simulated carbon cycle-climate feedbacks. This conclusion sheds new light on coupled climate-carbon cycle model results, and highlights the need for improved model representation of photosynthesis processes so as to better constrain future projections of climate change.”

How strong is carbon cycle-climate feedback under global warming? – Zeng et al. (2004) Thesis paper on modelling carbon cycle feedback. “The behavior of the coupled carbon cycle and physical climate system in a global warming scenario is studied using an Earth system model including the atmosphere, land, ocean, and the carbon cycle embedded in these components. … Results indicate a positive feedback to global warming from the interactive carbon cycle, with an additional increase of 90 ppmv in the atmospheric CO2, and 0.6 degree additional warming, thus confirming recent results from the Hadley Centre and IPSL.” [Link to PDF]

Quantifying the effects of CO2-fertilized vegetation on future global climate and carbon dynamics – Thompson et al. (2004) “In particular, the response of the land biosphere to the ongoing increase in atmospheric CO2 is not well understood. To evaluate the approximate upper and lower limits of land carbon uptake, we perform simulations using a comprehensive climate-carbon model. … In a second case, CO2 fertilization saturates in year 2000; here the land becomes an additional source of CO2 by 2050. The predicted atmospheric CO2 concentration at year 2100 differs by 40% between the two cases. We show that current uncertainties preclude determination of whether the land biosphere will amplify or damp atmospheric CO2 increases by the end of the century.” [Link to PDF]

How positive is the feedback between climate change and the carbon cycle? – Friedlingstein et al. (2003) “Here we perform a detailed feedback analysis to show that such differences are due to two key processes that are still poorly constrained in these coupled models: first Southern Ocean circulation, which primarily controls the geochemical uptake of CO2, and second vegetation and soil carbon response to global warming. Our analytical analysis reproduces remarkably the results obtained by the fully coupled models. Also it allows us to identify that, amongst the two processes mentioned above, the latter (the land response to global warming) is the one that essentially explains the differences between the IPSL and the Hadley results.” [Link to PDF]

Strong carbon cycle feedbacks in a climate model with interactive CO2 and sulphate aerosols – Jones et al. (2003) “A climate change experiment is presented which uses a General Circulation Model (GCM) in which both interactive carbon and sulphur cycles have been included for the first time, along with the natural climate forcings due to solar changes and volcanic aerosol. … The additional forcings act to delay by more than a decade the conversion of the land carbon sink to a source, but ultimately result in a more abrupt rate of CO2 increase with the land carbon source (which reaches 7 GtC yr-1 by 2100) exceeding the ocean carbon sink (which saturates at 5 GtC yr-1 by 2100) beyond about 2080.”

On the magnitude of positive feedback between future climate change and the carbon cycle – Dufresne et al. (2002) “We use an ocean-atmosphere general circulation model coupled to land and ocean carbon models to simulate the evolution of climate and atmospheric CO2 from 1860 to 2100. … By 2100, we estimate that atmospheric CO2 will be 18% higher due to the climate change impact on the carbon cycle. Such a positive feedback has also been found by Cox et al. [2000] . However, the amplitude of our feedback is three times smaller than the one they simulated. We show that the partitioning between carbon stored in the living biomass or in the soil, and their respective sensitivity to increased CO2 and climate change largely explain this discrepancy.” [Link to PDF]

Positive feedback between future climate change and the carbon cycle – Friedlingstein et al. (2001) “Here, using climate and carbon three‐dimensional models forced by a 1% per year increase in atmospheric CO2, we show that there is a positive feedback between the climate system and the carbon cycle. Climate change reduces land and ocean uptake of CO2, respectively by 54% and 35% at 4 × CO2. This negative impact implies that for prescribed anthropogenic CO2 emissions, the atmospheric CO2 would be higher than the level reached if climate change does not affect the carbon cycle. We estimate the gain of this climate‐carbon cycle feedback to be 10% at 2 × CO2 and 20% at 4 × CO2. This translates into a 15% higher mean temperature increase.”

Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model – Cox et al. (2000) “Here we present results from a fully coupled, three-dimensional carbon–climate model, indicating that carbon-cycle feedbacks could significantly accelerate climate change over the twenty-first century. We find that under a ‘business as usual’ scenario, the terrestrial biosphere acts as an overall carbon sink until about 2050, but turns into a source thereafter. By 2100, the ocean uptake rate of 5 Gt C yr-1 is balanced by the terrestrial carbon source, and atmospheric CO2 concentrations are 250 p.p.m.v. higher in our fully coupled simulation than in uncoupled carbon models, resulting in a global-mean warming of 5.5 K, as compared to 4 K without the carbon-cycle feedback.” [Link to PDF]

Closely related

Papers on methane emissions

Posted in AGW evidence | 2 Comments »

Papers on glacier melting

Posted by Ari Jokimäki on November 8, 2009

This is a list of papers on melting glaciers with emphasis on global observational analysis and mass balance measurements. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

UPDATE (September 17, 2010): Cogley (2009) added.
UPDATE (November 8, 2009): Few links added to the “closely related” section, thanks to mspelto for pointing them out, see the discussion section below. I also added Barry (2006).

Geodetic and direct mass-balance measurements: comparison and joint analysis – Cogley (2009) “This paper describes a new compilation of both direct and geodetic mass-balance measurements, develops a procedure to reduce diverse balance measurements over different time-spans to common time-spans, and presents updated estimates of global average balance of small glaciers based on the enlarged compilation. Although geodetic measurements are fewer than direct measurements, they cover four times as many balance years. Direct and geodetic measurements are unbiased with respect to one another, but differences are often substantial. The statistical procedure can be understood by imagining that an n-year balance measurement is an average of a series of 1 year measurements. The series is hypothetical but we can calculate the uncertainty of each of its elements if, in addition to its measured average, we can also estimate its standard deviation. For this claim to be valid, the annual series must be stationary and normally distributed with independent (roughly, uncorrelated) elements, for which there is reasonable evidence. The need to know the standard deviation means that annual direct measurements from a nearby glacier, or equally reliable information about variability, are indispensable. Given this information, the new methodology results in moderately more negative balances. This is probably because tidewater glaciers are better represented in the geodetic data. In any case, the most recent published estimate of global average balance, 0.8-1.0 mm a−1 of sea-level equivalent for 2001-04, is now increased substantially to 1.1-1.4 mm a−1 for 2001-05.” [Full text, data]

Six decades of glacier mass-balance observations: a review of the worldwide monitoring network – Zemp et al. (2009) A review paper. “Six decades of annual mass-balance data have been compiled and made easily available by the World Glacier Monitoring Service and its predecessor organizations. In total, there have been 3480 annual mass-balance measurements reported from 228 glaciers around the globe. … The available data from the six decades indicate a strong ice loss as early as the 1940s and 1950s followed by a moderate mass loss until the end of the 1970s and a subsequent acceleration that has lasted until now, culminating in a mean overall ice loss of over 20 m w.e. for the period 1946-2006.” [Link to PDF]

After six decades of monitoring glacier mass balance we still need data but it should be richer data – Braithwaite (2009) A review paper (which in my opinion could have a better title). “However, 30 year series from 30 glaciers confirm a recent (1996-2005) trend to very negative mass balance after two decades of nearly zero mass balance.” [Link to PDF]

Glaciers Dominate Eustatic Sea-Level Rise in the 21st Century – Meier et al. (2007) “The contribution of these smaller glaciers has accelerated over the past decade, in part due to marked thinning and retreat of marine-terminating glaciers associated with a dynamic instability that is generally not considered in mass-balance and climate modeling. This acceleration of glacier melt may cause 0.1 to 0.25 meter of additional sea-level rise by 2100”

The status of research on glaciers and global glacier recession: a review – Barry (2006) A review paper. “Nevertheless, there has been substantial glacier retreat since the Little Ice Age and this has accelerated over the last two to three decades. Documenting these changes is hampered by the paucity of observational data. This review outlines the measurements that are available, new techniques that incorporate remotely sensed data, and major findings around the world. The focus is on changes in glacier area, rather than estimates of mass balance and volume changes that address the role of glacier melt in global sea-level rise.” [Link to PDF]

Mass balance of glaciers and ice caps: Consensus estimates for 1961–2004 – Kaser et al. (2006) “Working with comprehensive collections of directly-measured data on the annual mass balance of glaciers other than the two ice sheets, we combine independent analyses to show that there is broad agreement on the evolution of global mass balance since 1960. Mass balance was slightly below zero around 1970 and has been growing more negative since then. Excluding peripheral ice bodies in Greenland and Antarctica, global average specific balance for 1961–1990 was −219 ± 112 kg m−2 a−1, representing 0.33 ± 0.17 mm SLE (sea-level equivalent) a−1. For 2001–2004, the figures are −510 ± 101 kg m−2 a−1 and 0.77±0.15 mm SLE a−1. Including the smaller Greenland and Antarctic glaciers, global total balance becomes 0.38 ± 0.19 mm SLE a−1 for 1961–1990 and 0.98 ± 0.19 mm SLE a−1 for 2001–2004. For 1991–2004 the glacier contribution, 0.77 ± 0.26 mm SLE a−1, is 20–30% of a recent estimate of 3.2 ± 0.4 mm a−1 of total sea-level rise for 1993–2005.” [Link to PDF]

Changes in mountain glaciers and ice caps during the 20th century – Ohmura (2006) “The global mass balance of the glaciers outside Greenland and Antarctica is evaluated based on long-term mass-balance observations on 75 glaciers. The cause of the mass-balance change is investigated by examining winter and summer balances from 34 glaciers. The main finding is a common development in mass-balance changes shared by a number of glaciers separated by large distances and climatic conditions. The average mass balance for the second half of the 20th century was negative at −270 to −280 mm a−1. The negative mass balance was found to be intensified at −10 mm a−2.” [Link to PDF]

Extracting a Climate Signal from 169 Glacier Records – Oerlemans et al. (2005) “I constructed a temperature history for different parts of the world from 169 glacier length records. Using a first-order theory of glacier dynamics, I related changes in glacier length to changes in temperature. … Moderate global warming started in the middle of the 19th century. The reconstructed warming in the first half of the 20th century is 0.5 kelvin.” [Link to PDF]

Secular glacier mass balances derived from cumulative glacier length changes – Hoelzle et al. (2003) “The mean specific mass balance determined from glacier length change data since 1900 shows considerable regional variability but centers around a mean value of about −0.25 m year−1 water equivalent.” [Link to PDF]

Glacier mass balance: the first 50 years of international monitoring – Braithwaite (2002) “The paper reviews measurements of glacier mass balance in the period 1946-95. There are data for 246 glaciers but most records are quite short. The available mass-balance data are biased to Western Europe, North America and the former USSR with too few measurements from other parts of the world. … There is no sign of any recent global trend towards increased glacier melting, and the data mainly reflect variations within and between regions.”

Glacier Mass Balance and Regime: Data of Measurements and Analysis – Duyrgerov et al. (2002) “This is the most complete data set of parameters of glacier regime have ever been compiled and published before. Data presented in appendixes include annual mass balances and related variables of mountain and subpolar glaciers outside the two major ice sheets. … The rate of annual melt-water production (ablation) by glaciers has been increasing, and comprised of about 1.7 m/yr in water equivalent for the period. … The equilibrium-line altitude has risen by 200 m…” [Link to PDF]

On Rates and Acceleration Trends of Global Glacier Mass Changes – Haeberli et al. (1999) “During the coming decades, excess radiation income and sensible heat (a few watts per square metre) as calculated with numerical climate models are both estimated to increase by a factor of about two to four as compared to the mean of the 20th century. The rate of average annual mass loss (a few decimetres per year) measured today on mountain glaciers in various parts of the world now appears to accelerate accordingly, even though detailed interpretation of the complex processes involved remains difficult. Within the framework of secular glacier retreat and Holocene glacier fluctuations, similar rates of change and acceleration must have taken place before, i.e. during times of weak anthropogenic forcing. However, the anthropogenic influences on the atmosphere could now and for the first time represent a major contributing factor to the observed glacier shrinkage at a global scale. Problems with such assessments mainly concern aspects of statistical averaging, regional climate variability, strong differences in glacier sensitivity and relations between mass balance and cumulative glacier length change over decadal to secular time scales. Considerable progress has recently been achieved in these fields of research.”

Mass balance of glaciers other than the ice sheets – Cogley & Adams (1998) “Small glaciers appear to have been at equilibrium or shrinking very slightly during 1961-90, according to analysis of an essentially complete set of published measurements. Simple calculations give an average annual mass balance of 195±59 mm a-1 (water equivalent but this is too low because of systematic errors. … Among the 231 measured glaciers, many are small and belong to a restricted size range in which balance is negative, but much of the small-glacier extent is accounted for by larger glaciers in a size range where balance is indistinguishable from zero. Correcting for this size bias increases the average balance to 35 ±89 mm a-1. Inspection of time series for 1940-95 (251 glaciers shows that mass balance was least negative during the 1960s, and has varied in broad agreement with Northern Hemisphere temperature anomalies;”

Year-to-Year Fluctuations of Global Mass Balance of Small Glaciers and Their Contribution to Sea-Level Changes – Dyurgerov & Meier (1997) “We estimate the means and the interannual variability during the last 30 yr of the mass balances of the small glaciers of the world (all glaciers except for the two large ice sheets), as well as the influence of these mass balance changes on fluctuations of sea level and their relation to climate. … [Area weighted mean] produces a new global mass balance value, averaging -130 +/- 33 mm yr-1, totaling -3.9 m in water equivalent for 1961-1990 period…”

Mass Balance of Mountain and Subpolar Glaciers: A New Global Assessment for 1961-1990 – Dyurgerov & Meier (1997) “The goals of this article are (1) to combine published and unpublished mass balance measured data on more than 200 glaciers, check the quality of the data, digitize, and compile these for the period from the end of World War II (1945) to 1993 (with emphasis on the 1961-1990 period), and (2) to perform a review and analysis of this compilation. A simple global average mass balance for this period is -164 mm yr-1 (totaling -4.9 m) in water equivalent, not including iceberg calving.” [Link to PDF]

Quantifying Global Warming from the Retreat of Glaciers – Oerlemans et al. (1994) “Records of glacier fluctuations compiled by the World Glacier Monitoring Service can be used to derive an independent estimate of global warming during the last 100 years. … The retreat of glaciers during the last 100 years appears to be coherent over the globe. On the basis of modeling of the climate sensitivity of glaciers, the observed glacier retreat can be explained by a linear warming trend of 0.66 kelvin per century.” [Link to PDF]

Contribution of Small Glaciers to Global Sea Level – Meier (1984) “The average observed volume change for the period 1900 to 1961 is scaled to a global average by use of the seasonal amplitude of the mass balance. These data are used to calibrate the models to estimate the changing contribution of glaciers to sea level for the period 1884 to 1975. Although the error band is large, these glaciers appear to account for a third to half of observed rise in sea level, approximately that fraction not explained by thermal expansion of the ocean.”

Closely related

Basics of glacier mass balance are given in this article by Mauri Pelto (and more here).

World Glacier Monitoring Service and their Mass Balance Bulletin (Some of the MBB PDF’s are very large, over 10MB or even over 20MB).

Posted in AGW evidence | 6 Comments »

Papers on climate sensitivity estimates

Posted by Ari Jokimäki on November 5, 2009

This is a list of papers on climate sensitivity estimates. The list is based on the “Estimates of Climate Sensitivity” by Barton Paul Levenson (2006), with some additions from John Cook’s article on climate sensitivity and from my own searches. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

UPDATE (April 18, 2013): Lewis (2013), Masters (2013), and van Hateren (2012) added. Thanks to Kevin C. for pointing them out.
UPDATE (March 25, 2013): PALAEOSENS Project Members (2012) and Hargreaves et al. (2012) added.
UPDATE (March 22, 2013): Köhler et al. (2010), Pagani et al. (2010), Schmittner et al. (2011), Bitz et al. (2012) added.
UPDATE (April 2, 2012): Annan & Hargreaves (2009) added. Thanks to Barry for pointing it out.
UPDATE (June 16, 2010): Huybers (2010) added.
UPDATE (May 10, 2010): Lunt et al. (2010) added.
UPDATE (February 26, 2010): Hulburt (1931) added.
UPDATE (February 16, 2010): Lea (2004) added, thanks to Barry for pointing it out, see the comment section below.
UPDATE (November 7, 2009): Kirk-Davidoff (2009), an additional note to Schwartz (2007), and Covey et al. (1996) added, thanks to PeterPan for suggesting these.
UPDATE (November 6, 2009): I forgot to include Schwartz (2007), I added it now. I also added Schwartz’s response to critics, thanks to Paul Middents for pointing it out, see the discussion section below.

Newer papers and other papers not in Levenson’s list:

Observational estimate of climate sensitivity from changes in the rate of ocean heat uptake and comparison to CMIP5 models – Masters (2013) “Climate sensitivity is estimated based on 0–2,000 m ocean heat content and surface temperature observations from the second half of the 20th century and first decade of the 21st century, using a simple energy balance model and the change in the rate of ocean heat uptake to determine the radiative restoration strength over this time period. The relationship between this 30–50 year radiative restoration strength and longer term effective sensitivity is investigated using an ensemble of 32 model configurations from the Coupled Model Intercomparison Project phase 5 (CMIP5), suggesting a strong correlation between the two. The mean radiative restoration strength over this period for the CMIP5 members examined is 1.16 Wm−2K−1, compared to 2.05 Wm−2K−1 from the observations. This suggests that temperature in these CMIP5 models may be too sensitive to perturbations in radiative forcing, although this depends on the actual magnitude of the anthropogenic aerosol forcing in the modern period. The potential change in the radiative restoration strength over longer timescales is also considered, resulting in a likely (67 %) range of 1.5–2.9 K for equilibrium climate sensitivity, and a 90 % confidence interval of 1.2–5.1 K.” Troy Masters, Climate Dynamics, April 2013, DOI: 10.1007/s00382-013-1770-4.

An objective Bayesian, improved approach for applying optimal fingerprint techniques to estimate climate sensitivity – Lewis (2013) “A detailed reanalysis is presented of a ‘Bayesian’ climate parameter study (Forest et al., 2006) that estimates climate sensitivity (ECS) jointly with effective ocean diffusivity and aerosol forcing, using optimal fingerprints to compare multi-decadal observations with simulations by the MIT 2D climate model at varying settings of the three climate parameters. Use of improved methodology primarily accounts for the 90% confidence bounds for ECS reducing from 2.1–8.9 K to 2.0–3.6 K. The revised methodology uses Bayes’ theorem to derive a probability density function (PDF) for the whitened (made independent using an optimal fingerprint transformation) observations, for which a uniform prior is known to be noninformative. A dimensionally-reducing change of variables onto the parameter surface is then made, deriving an objective joint PDF for the climate parameters. The PDF conversion factor from the whitened variables space to the parameter surface represents a noninformative joint parameter prior, which is far from uniform. The noninformative prior prevents more probability than data uncertainty distributions warrant being assigned to regions where data responds little to parameter changes, producing better-constrained PDFs. Incorporating six years of unused model-simulation data and revising the experimental design to improve diagnostic power reduces the best-fit climate sensitivity. Employing the improved methodology, preferred 90% bounds of 1.2–2.2 K for ECS are then derived (mode and median 1.6 K). The mode is identical to those from Aldrin et al. (2012) and (using the same, HadCRUT4, observational dataset) Ring et al. (2012). Incorporating forcing and observational surface temperature uncertainties, unlike in the original study, widens the 90% range to 1.0–3.0 K.” Nicholas Lewis, Journal of Climate 2013, doi:

A fractal climate response function can simulate global average temperature trends of the modern era and the past millennium – van Hateren (2012) “A climate response function is introduced that consists of six exponential (low-pass) filters with weights depending as a power law on their e-folding times. The response of this two-parameter function to the combined forcings of solar irradiance, greenhouse gases, and SO2-related aerosols is fitted simultaneously to reconstructed temperatures of the past millennium, the response to solar cycles, the response to the 1991 Pinatubo volcanic eruption, and the modern 1850–2010 temperature trend. Assuming strong long-term modulation of solar irradiance, the quite adequate fit produces a climate response function with a millennium-scale response to doubled CO2 concentration of 2.0 ± 0.3 °C (mean ± standard error), of which about 50 % is realized with e-folding times of 0.5 and 2 years, about 30 % with e-folding times of 8 and 32 years, and about 20 % with e-folding times of 128 and 512 years. The transient climate response (response after 70 years of 1 % yearly rise of CO2 concentration) is 1.5 ± 0.2 °C. The temperature rise from 1820 to 1950 can be attributed for about 70 % to increased solar irradiance, while the temperature changes after 1950 are almost completely produced by the interplay of anthropogenic greenhouse gases and aerosols. The SO2-related forcing produces a small temperature drop in the years 1950–1970 and an inflection of the temperature curve around the year 2000. Fitting with a tenfold smaller modulation of solar irradiance produces a less adequate fit with millennium-scale and transient climate responses of 2.5 ± 0.4 and 1.9 ± 0.3 °C, respectively.” J. H. van Hateren, Climate Dynamics, May 2012, DOI: 10.1007/s00382-012-1375-3. [Full text]

Can the Last Glacial Maximum constrain climate sensitivity? – Hargreaves et al. (2012) “We investigate the relationship between the Last Glacial Maximum (LGM) and climate sensitivity across the PMIP2 multi-model ensemble of GCMs, and find a correlation between tropical temperature and climate sensitivity which is statistically significant and physically plausible. We use this relationship, together with the LGM temperature reconstruction of Annan and Hargreaves (2012), to generate estimates for the equilibrium climate sensitivity. We estimate the equilibrium climate sensitivity to be about 2.5°C with a high probability of being under 4°C, though these results are subject to several important caveats. The forthcoming PMIP3/CMIP5 models were not considered in this analysis, as very few LGM simulations are currently available from these models. We propose that these models will provide a useful validation of the correlation presented here.” J. C. Hargreaves, J. D. Annan, M. Yoshimori, A. Abe-Ouchi, Geophysical Research Letters, Volume 39, Issue 24, December 2012, DOI: 10.1029/2012GL053872. [Full text]

Making sense of palaeoclimate sensitivity – PALAEOSENS Project Members (2012) “Many palaeoclimate studies have quantified pre-anthropogenic climate change to calculate climate sensitivity (equilibrium temperature change in response to radiative forcing change), but a lack of consistent methodologies produces a wide range of estimates and hinders comparability of results. Here we present a stricter approach, to improve intercomparison of palaeoclimate sensitivity estimates in a manner compatible with equilibrium projections for future climate change. Over the past 65 million years, this reveals a climate sensitivity (in K W−1 m2) of 0.3–1.9 or 0.6–1.3 at 95% or 68% probability, respectively. The latter implies a warming of 2.2–4.8 K per doubling of atmospheric CO2, which agrees with IPCC estimates.” PALAEOSENS Project Members, Nature, 491, 683–691, 29 November 2012, DOI: 10.1038/nature11574.

Climate Sensitivity of the Community Climate System Model, Version 4 – Bitz et al. (2012) “Equilibrium climate sensitivity of the Community Climate System Model, version 4 (CCSM4) is 3.20°C for 1° horizontal resolution in each component. This is about a half degree Celsius higher than in the previous version (CCSM3). The transient climate sensitivity of CCSM4 at 1° resolution is 1.72°C, which is about 0.2°C higher than in CCSM3. These higher climate sensitivities in CCSM4 cannot be explained by the change to a preindustrial baseline climate. This study uses the radiative kernel technique to show that, from CCSM3 to CCSM4, the global mean lapse-rate feedback declines in magnitude and the shortwave cloud feedback increases. These two warming effects are partially canceled by cooling because of slight decreases in the global mean water vapor feedback and longwave cloud feedback from CCSM3 to CCSM4. A new formulation of the mixed layer, slab-ocean model in CCSM4 attempts to reproduce the SST and sea ice climatology from an integration with a full-depth ocean, and it is integrated with a dynamic sea ice model. These new features allow an isolation of the influence of ocean dynamical changes on the climate response when comparing integrations with the slab ocean and full-depth ocean. The transient climate response of the full-depth ocean version is 0.54 of the equilibrium climate sensitivity when estimated with the new slab-ocean model version for both CCSM3 and CCSM4. The authors argue the ratio is the same in both versions because they have about the same zonal mean pattern of change in ocean surface heat flux, which broadly resembles the zonal mean pattern of net feedback strength.” Bitz, C. M., K. M. Shell, P. R. Gent, D. A. Bailey, G. Danabasoglu, K. C. Armour, M. M. Holland, J. T. Kiehl, 2012: Climate Sensitivity of the Community Climate System Model, Version 4. J. Climate, 25, 3053–3070. doi:

Climate Sensitivity Estimated from Temperature Reconstructions of the Last Glacial Maximum – Schmittner et al. (2011) “Assessing the impact of future anthropogenic carbon emissions is currently impeded by uncertainties in our knowledge of equilibrium climate sensitivity to atmospheric carbon dioxide doubling. Previous studies suggest 3 kelvin (K) as the best estimate, 2 to 4.5 K as the 66% probability range, and nonzero probabilities for much higher values, the latter implying a small chance of high-impact climate changes that would be difficult to avoid. Here, combining extensive sea and land surface temperature reconstructions from the Last Glacial Maximum with climate model simulations, we estimate a lower median (2.3 K) and reduced uncertainty (1.7 to 2.6 K as the 66% probability range, which can be widened using alternate assumptions or data subsets). Assuming that paleoclimatic constraints apply to the future, as predicted by our model, these results imply a lower probability of imminent extreme climatic change than previously thought.” Andreas Schmittner, Nathan M. Urban, Jeremy D. Shakun, Natalie M. Mahowald, Peter U. Clark, Patrick J. Bartlein, Alan C. Mix, Antoni Rosell-Melé, Science 9 December 2011: Vol. 334 no. 6061 pp. 1385-1388, DOI: 10.1126/science.1203513. [Full text]

High Earth-system climate sensitivity determined from Pliocene carbon dioxide concentrations – Pagani et al. (2010) “Climate sensitivity—the mean global temperature response to a doubling of atmospheric CO2 concentrations through radiative forcing and associated feedbacks—is estimated at 1.5–4.5 °C (ref. 1). However, this value incorporates only relatively rapid feedbacks such as changes in atmospheric water vapour concentrations, and the distributions of sea ice, clouds and aerosols. Earth-system climate sensitivity, by contrast, additionally includes the effects of long-term feedbacks such as changes in continental ice-sheet extent, terrestrial ecosystems and the production of greenhouse gases other than CO2. Here we reconstruct atmospheric carbon dioxide concentrations for the early and middle Pliocene, when temperatures were about 3–4 °C warmer than preindustrial values, to estimate Earth-system climate sensitivity from a fully equilibrated state of the planet. We demonstrate that only a relatively small rise in atmospheric CO2 levels was associated with substantial global warming about 4.5 million years ago, and that CO2 levels at peak temperatures were between about 365 and 415 ppm. We conclude that the Earth-system climate sensitivity has been significantly higher over the past five million years than estimated from fast feedbacks alone.” Mark Pagani, Zhonghui Liu, Jonathan LaRiviere & Ana Christina Ravelo, Nature Geoscience 3, 27 – 30 (2010), doi:10.1038/ngeo724. [Full text]

Compensation between Model Feedbacks and Curtailment of Climate Sensitivity – Huybers (2010) “The spread in climate sensitivity obtained from 12 general circulation model runs used in the Fourth Assessment of the Intergovernmental Panel on Climate Change indicates a 95% confidence interval of 2.1°–5.5°C, but this reflects compensation between model feedbacks. In particular, cloud feedback strength negatively covaries with the albedo feedback as well as with the combined water vapor plus lapse rate feedback. If the compensation between feedbacks is removed, the 95% confidence interval for climate sensitivity expands to 1.9°–8.0°C.”

Earth system sensitivity inferred from Pliocene modelling and data – Lunt et al. (2010) “Components of the Earth’s climate system that vary over long timescales, such as ice sheets and vegetation, could have an important effect on this temperature sensitivity, but have often been neglected. Here we use a coupled atmosphere–ocean general circulation model to simulate the climate of the mid-Pliocene warm period (about three million years ago), and analyse the forcings and feedbacks that contributed to the relatively warm temperatures. Furthermore, we compare our simulation with proxy records of mid-Pliocene sea surface temperature. Taking these lines of evidence together, we estimate that the response of the Earth system to elevated atmospheric carbon dioxide concentrations is 30–50% greater than the response based on those fast-adjusting components of the climate system that are used traditionally to estimate climate sensitivity.” [Full text]

What caused Earth’s temperature variations during the last 800,000 years? Data-based evidence on radiative forcing and constraints on climate sensitivity – Köhler et al. (2010) “The temperature on Earth varied largely in the Pleistocene from cold glacials to interglacials of different warmths. To contribute to an understanding of the underlying causes of these changes we compile various environmental records (and model-based interpretations of some of them) in order to calculate the direct effect of various processes on Earth’s radiative budget and, thus, on global annual mean surface temperature over the last 800,000 years. The importance of orbital variations, of the greenhouse gases CO2, CH4 and N2O, of the albedo of land ice sheets, annual mean snow cover, sea ice area and vegetation, and of the radiative perturbation of mineral dust in the atmosphere are investigated. Altogether we can explain with these processes a global cooling of 3.9 ± 0.8 K in the equilibrium temperature for the Last Glacial Maximum (LGM) directly from the radiative budget using only the Planck feedback that parameterises the direct effect on the radiative balance, but neglecting other feedbacks such as water vapour, cloud cover, and lapse rate. The unaccounted feedbacks and related uncertainties would, if taken at present day feedback strengths, decrease the global temperature at the LGM by −8.0 ± 1.6 K. Increased Antarctic temperatures during the Marine Isotope Stages 5.5, 7.5, 9.3 and 11.3 are in our conceptual approach difficult to explain. If compared with other studies, such as PMIP2, this gives supporting evidence that the feedbacks themselves are not constant, but depend in their strength on the mean climate state. The best estimate and uncertainty for our reconstructed radiative forcing and LGM cooling support a present day equilibrium climate sensitivity (excluding the ice sheet and vegetation components) between 1.4 and 5.2 K, with a most likely value near 2.4 K, somewhat smaller than other methods but consistent with the consensus range of 2–4.5 K derived from other lines of evidence. Climate sensitivities above 6 K are difficult to reconcile with Last Glacial Maximum reconstructions.” Peter Köhler, Richard Bintanja, Hubertus Fischer, Fortunat Joos, Reto Knutti, Gerrit Lohmann, Valérie Masson-Delmotte, Quaternary Science Reviews, Volume 29, Issues 1–2, January 2010, Pages 129–145, [Full text]

On the generation and interpretation of probabilistic estimates of climate sensitivity – Annan & Hargreaves (2009) “The equilibrium climate response to anthropogenic forcing has long been one of the dominant, and therefore most intensively studied, uncertainties in predicting future climate change. As a result, many probabilistic estimates of the climate sensitivity (S) have been presented. In recent years, most of them have assigned significant probability to extremely high sensitivity, such as P(S > 6C) > 5%. In this paper, we investigate some of the assumptions underlying these estimates. We show that the popular choice of a uniform prior has unacceptable properties and cannot be reasonably considered to generate meaningful and usable results. When instead reasonable assumptions are made, much greater confidence in a moderate value for S is easily justified, with an upper 95% probability limit for S easily shown to lie close to 4°C, and certainly well below 6°C. These results also impact strongly on projected economic losses due to climate change.” J. D. Annan and J. C. Hargreaves, Climatic Change, Volume 104, Numbers 3-4, 423-436, DOI: 10.1007/s10584-009-9715-y [Full text]

On the diagnosis of climate sensitivity using observations of fluctuations – Kirk-Davidoff (2009) “It has been shown that lag-covariance based statistical measures, suggested by the Fluctuation Dissipation Theorem (FDT), may allow estimation of climate sensitivity in a climate model. Recently Schwartz (2007) has used measures of the decay of autocorrelation in a global surface temperature time series to estimate the real world climate sensitivity. Here we use a simple climate model, and analysis of archived coupled climate model output from the IPCC AR4 runs, for which the climate sensitivity is known, to test the utility of this approach. Our analysis of these archived model output data show that estimates of climate sensitivity derived from century-long time scales typically grossly underestimate the models’ true climate sensitivity.” [Full text]

Complementary observational constraints on climate sensitivity – Urban & Keller (2009) “Here we show that reducing the uncertainty about (i) oceanic heat uptake and (ii) aerosol climate forcing can—in principle—cut off this heavy upper tail of climate sensitivity estimates. Observations of oceanic heat uptake result in a negatively correlated joint likelihood function of climate sensitivity and ocean vertical diffusivity. This correlation is opposite to the positive correlation resulting from observations of surface air temperatures. As a result, the two observational constraints can rule out complementary regions in the climate sensitivity-vertical diffusivity space, and cut off the heavy upper tail of the marginal climate sensitivity estimate.” [Full text]

Insufficient forcing uncertainty underestimates the risk of high climate sensitivity – Tanaka et al. (2009) An example that shows how uncertainty in climate sensitivity estimates doesn’t necessarily mean that climate sensitivity is low. “In spite of various efforts to estimate its value, climate sensitivity is still not well constrained. Here we show that the probability of high climate sensitivity is higher than previously thought because uncertainty in historical radiative forcing has not been sufficiently considered. The greater the uncertainty that is considered for radiative forcing, the more difficult it is to rule out high climate sensitivity, although low climate sensitivity (<2°C) remains unlikely.” [Full text]

Target atmospheric CO2: Where should humanity aim? – Hansen et al. (2008) “Paleoclimate data show that climate sensitivity is ~3°C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6°C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica.” [Full text]

The equilibrium sensitivity of the Earth’s temperature to radiation changes – Knutti et al. (2008) A review article. “The quest to determine climate sensitivity has now been going on for decades, with disturbingly little progress in narrowing the large uncertainty range. However, in the process, fascinating new insights into the climate system and into policy aspects regarding mitigation have been gained. The well-constrained lower limit of climate sensitivity and the transient rate of warming already provide useful information for policy makers. But the upper limit of climate sensitivity will be more difficult to quantify.” [Full text]

Aerosol radiative forcing and climate sensitivity deduced from the Last Glacial Maximum to Holocene transition – Chylek & Lohmann (2008) “We use the temperature, carbon dioxide, methane, and dust concentration record from the Vostok ice core to deduce the aerosol radiative forcing during the Last Glacial Maximum (LGM) to Holocene transition and the climate sensitivity. … This suggests a 95% likelihood of warming between 1.3 and 2.3 K due to doubling of atmospheric concentration of CO2.”

Climate sensitivity constrained by CO2 concentrations over the past 420 million years – Royer et al. (2007) “Here we estimate long-term equilibrium climate sensitivity by modelling carbon dioxide concentrations over the past 420 million years and comparing our calculations with a proxy record. Our estimates are broadly consistent with estimates based on short-term climate records, and indicate that a weak radiative forcing by carbon dioxide is highly unlikely on multi-million-year timescales. We conclude that a climate sensitivity greater than 1.5 °C has probably been a robust feature of the Earth’s climate system over the past 420 million years, regardless of temporal scaling.” [Full text]

Heat capacity, time constant, and sensitivity of Earth’s climate system – Schwartz (2007) See John Cook’s article for some comments on this paper. Note that in the response to critics Schwartz revises the estimated sensitivity from 1.1 K to 1.9 K. “The equilibrium sensitivity of Earth’s climate is determined as the quotient of the relaxation time constant of the system and the pertinent global heat capacity. … The resultant equilibrium climate sensitivity, 0.30 ± 0.14 K/(W m−2), corresponds to an equilibrium temperature increase for doubled CO2 of 1.1 ± 0.5 K.” [Full text] [Link to Schwartz’s response to critics]

Using multiple observationally-based constraints to estimate climate sensitivity – Annan & Hargreaves (2006) “Climate sensitivity has been subjectively estimated to be likely to lie in the range of 1.5–4.5°C, and this uncertainty contributes a substantial part of the total uncertainty in climate change projections over the coming century. Objective observationally-based estimates have so far failed to improve on this upper bound, with many estimates even suggesting a significant probability of climate sensitivity exceeding 6°C. In this paper, we show how it is possible to greatly reduce this uncertainty by using Bayes’ Theorem to combine several independent lines of evidence. Based on some conservative assumptions regarding the value of independent estimates, we conclude that climate sensitivity is very unlikely (<5% probability) to exceed 4.5°C. We cannot assign a significant probability to climate sensitivity exceeding 6°C without making what appear to be wholly unrealistic exaggerations about the uncertainties involved. This represents a significant lowering of the previously-estimated bound.” [Full text]

Constraining Climate Sensitivity from the Seasonal Cycle in Surface Temperature – Knutti et al. (2006) “A probability density function for climate sensitivity is then calculated from the present-day seasonal cycle in reanalysis and instrumental datasets. Subject to a number of assumptions on the models and datasets used, it is found that climate sensitivity is very unlikely (5% probability) to be either below 1.5–2 K or above about 5–6.5 K, with the best agreement found for sensitivities between 3 and 3.5 K.” [Full text]

The 100 000-Yr Cycle in Tropical SST, Greenhouse Forcing, and Climate Sensitivity – Lea (2004) “Two recent advances, the development and application of proxy recorders of tropical sea surface temperature (SST) and the synchronization of the deep-sea and Antarctic ice-core time scales, make it possible to directly relate past changes in tropical SST to atmospheric carbon dioxide (CO2) levels. The strong correspondence of a proxy SST record from the eastern equatorial Pacific and the Vostok CO2 record suggests that varying atmospheric carbon dioxide is the dominant control on tropical climate on orbital time scales. This effect is especially pronounced at the 100 000-yr cycle. Calibration of the CO2 influence via tropical SST variability indicates a tropical climate sensitivity of 4.4°–5.6°C (errors estimated at ± 1.0°C) for a doubling of atmospheric CO2 concentration. This result suggests that the equilibrium response of tropical climate to atmospheric CO2 changes is likely to be similar to the upper end of available global predictions from coupled models.” [Full text]

An Observationally Based Estimate of the Climate Sensitivity – Gregory et al. (2002) “A probability distribution for values of the effective climate sensitivity, with a lower bound of 1.6 K (5th percentile), is obtained on the basis of the increase in ocean heat content in recent decades from analyses of observed interior-ocean temperature changes, surface temperature changes measured since 1860, and estimates of anthropogenic and natural radiative forcing of the climate system.” [Full text]

Quantifying Uncertainties in Climate System Properties with the Use of Recent Climate Observations – Forest et al. (2002) “We derive joint probability density distributions for three key uncertain properties of the climate system, using an optimal fingerprinting approach to compare simulations of an intermediate complexity climate model with three distinct diagnostics of recent climate observations. On the basis of the marginal probability distributions, the 5 to 95% confidence intervals are 1.4 to 7.7 kelvin for climate sensitivity and -0.30 to -0.95 watt per square meter for the net aerosol forcing.” [Full text]

Paleoclimate data constraints on climate sensitivity: The paleocalibration method – Covey et al. (1996) “We use a new technique called paleocalibration to calculate the ratio of temperature response to forcing on a global mean scale for three key intervals of Earth history. By examining surface conditions reconstructed from geologic data for the Last Glacial Maximum, the middle Cretaceous and the early Eocene, we can estimate the equilibrium climate sensitivity to radiative forcing changes for different extreme climates. We find that the ratios for these three periods, within error bounds, all lie in the range obtained from general circulation models: 2–5 K global warming for doubled atmospheric carbon dioxide. Paleocalibration thus provides a data-based confirmation of theoretically calculated climate sensitivity.”

How Sensitive Is the World’s Climate? – Hansen et al. (1993) “But climate models are mainly a tool that helps extract information from real-world climate changes. The principal climate characteristic to be evaluated is the global climate sensitivity to a perturbing forcing, such as a change of atmospheric composition. Our most precise knowledge of climate sensitivity comes from data on ancient and recent climate changes.” [Full text]

The ice-core record: climate sensitivity and future greenhouse warming – Lorius et al. (1990) “The prediction of future greenhouse-gas-induced warming depends critically on the sensitivity of Earth’s climate to increasing atmospheric concentrations of these gases. Data from cores drilled in polar ice sheets show a remarkable correlation between past glacial–interglacial temperature changes and the inferred atmospheric concentration of gases such as carbon dioxide and methane. These and other palaeoclimate data are used to assess the role of greenhouse gases in explaining past global climate change, and the validity of models predicting the effect of increasing concentrations of such gases in the atmosphere.” [Full text]

The Temperature of the Lower Atmosphere of the Earth – Hulburt (1931) “Calculation shows that doubling or tripling the amount of the carbon dioxide of the atmosphere increases the average sea level temperature by about 4° and 7°K, respectively; halving or reducing to zero the carbon dioxide decreases the temperature by similar amounts. Such changes in temperature are about the same as those which occur when the earth passes from an ice age to a warm age, or vice versa. Thus the calculation indicates that the carbon dioxide theory of the ice ages, originally proposed by Tyndall, is a possible theory.”

Papers in Levenson’s list:

The origin of the European “Medieval Warm Period” – Goosse et al. (2006) “ECBILT-CLIO-VECODE has a relatively weak climate sensitivity, with a 1.8°C increase in global mean temperature in response to a doubling of atmospheric CO2 concentration.” [Full text]

Climate sensitivity constrained by temperature reconstructions over the past seven centuries – Hegerl et al. (2006) “A number of observational studies, however, find a substantial probability of significantly higher sensitivities, yielding upper limits on climate sensitivity of 7.7 K to above 9 K (refs 3–8). Here we demonstrate that such observational estimates of climate sensitivity can be tightened if reconstructions of Northern Hemisphere temperature over the past several centuries are considered. … After accounting for the uncertainty in reconstructions and estimates of past external forcing, we find an independent estimate of climate sensitivity that is very similar to those from instrumental data. If the latter are combined with the result from all proxy reconstructions, then the 5–95 per cent range shrinks to 1.5–6.2 K, thus substantially reducing the probability of very high climate sensitivity.” [Full text]

An atmosphere–ocean time series model of global climate change – Stern (2005) “A time series model of the atmosphere–ocean climate system is developed, in which surface temperature (atmospheric temperature over land and sea surface temperature) moves towards a long-run equilibrium with both radiative forcing and ocean heat content, while ocean heat content accumulates the deviations from atmospheric equilibrium. … The resulting parameter estimates are closer to theoretically expected values than those of previous time series models and the estimated climate sensitivity to a doubling of carbon dioxide is 4.4 K.” [Full text]

Global Warming Simulation due to the High Resolution Climate Model by Using the Earth Simulator – Sumi (2005) “Various simulations are conducted following IPCC guidance and these results are submitted to IPCC Data Center. Warming of the global averaged surface temperature is consistent to the previous estimate.” [Full text]

Dynamical aspects of climate sensitivity – Boer & Yu (2003) “Dynamical aspects of climate feedback/sensitivity are investigated in climate change simulations with a common atmospheric general circulation model coupled to a full ocean model, which responds both dynamically and thermo-dynamically, and to a mixed-layer ocean component which responds only thermodynamically.” [Full text]

Celestial driver of Phanerozoic climate? – Shaviv & Veizer (2003) “We find that at least 66% of the variance in the paleotemperature trend could be attributed to CRF variations likely due to solar system passages through the spiral arms of the galaxy. Assuming that the entire residual variance in temperature is due solely to the CO2 greenhouse effect, we propose a tentative upper limit to the long-term “equilibrium” warming effect of CO2, one which is potentially lower than that based on general circulation models.” [Full text]

Climates of the Twentieth and Twenty-First Centuries Simulated by the NCAR Climate System Model – Dai et al. (2001) “The Climate System Model, a coupled global climate model without “flux adjustments” recently developed at the National Center for Atmospheric Research, was used to simulate the twentieth-century climate using historical greenhouse gas and sulfate aerosol forcing. … The projected global surface warming from the 1990s to the 2090s is 1.9°C under the BAU scenario and 1.5°C under the STA550 scenario. In both cases, the midstratosphere cools due to the increase in CO2, whereas the lower stratosphere warms in response to recovery of the ozone layer.” [Full text]

Committed warming and its implications for climate change – Wetherald et al. (2001) “Time lags between changes in radiative forcing and the resulting simulated climate responses are investigated in a set of transient climate change experiments. … Results suggest that if the radiative forcing is held fixed at today’s levels, the global mean SAT will rise an additional 1.0K before equilibrating. This unrealized warming commitment is larger than the 0.6K warming observed since 1900.” [Full text]

A transient climate change simulation with greenhouse gas and aerosol forcing: experimental design and comparison with the instrumental record for the twentieth century – Boer et al. (2000) “The Canadian Centre for Climate Modelling and Analysis (CCCma) global coupled model is used to investigate the potential climate effects of increasing greenhouse gas (GHG) concentrations and changes in sulfate aerosol loadings. … Simulations of the evolution of temperature and precipitation from 1900 to the present are compared with available observations. … IPCC 1990 estimates that the climate sensitivity falls in the range 1.5 to 4.5 °C so that the CCCma model sensitivity at 3.5 °C is in the upper half of this range.” [Full text]

Parallel climate model (PCM) control and transient simulations – Washington et al. (2000) “Results from a 300 year present-day coupled climate control simulation are presented, as well as for a transient 1% per year compound CO2 increase experiment which shows a global warming of 1.27 °C for a 10 year average at the doubling point of CO2 and 2.89 °C at the quadrupling point. … A 0.5% per year CO2 increase experiment also was performed showing a global warming of 1.5 °C around the time of CO2 doubling and a similar warming pattern to the 1% CO2 per year increase experiment.” [Full text]

Coupled climate modelling at GFDL: Recent accomplishment and future plans – Delworth et al. (1999) (CLIVAR Exchanges 4(4), 15-20)

Transient Climate Change Simulations with a Coupled Atmosphere–Ocean GCM Including the Tropospheric Sulfur Cycle – Roeckner et al. (1999) “The time-dependent climate response to changing concentrations of greenhouse gases and sulfate aerosols is studied using a coupled general circulation model of the atmosphere and the ocean (ECHAM4/OPYC3). … As in previous experiments, the climate response is similar, but weaker, if aerosol effects are included in addition to greenhouse gases.” [Full text]

Effective thermal conduction model for estimating global warming – Wolbarst (1999) “This paper presents a simple way to approximate the dependence of the global mean air temperature at Earth’s surface on the atmospheric concentration of carbon dioxide. It treats the atmosphere as a blanket, the effective thermal conductivity of which is a decreasing function of the amount of CO2 present, and does not involve the details of energy transport.”

Climate simulation at the secular time scale – Bertrand (1998) (Thèse de doctorat, Université catholique de Louvain, 208 pp.)

Transient Climate Change in the CSIRO Coupled Model with Dynamic Sea Ice – Gordon & O’Farrell (1997) “The CSIRO coupled model has been used in a “transient” greenhouse experiment. … The transient experiment (1% increase in CO2 compounding per annum) gave a 2°C warming at time of CO2 doubling. The model displayed a “cold start” effect with a (maximum) value estimated at 0.3°C.” [Full text]

Multi-fingerprint detection and attribution analysis of greenhouse gas, greenhouse gas-plus-aerosol and solar forced climate change – Hegerl et al. (1997) “A multi-fingerprint analysis is applied to the detection and attribution of anthropogenic climate change.” [Full text]

An Estimation of the Climatic Effects of Stratospheric Ozone Losses during the 1980s – MacKay et al. (1997) “Ozone perturbations at high latitudes result in a cooling of the surface–troposphere system that is greater (by a factor of 2.8) than that estimated from the change in radiative forcing resulting from ozone depletion and the model’s 2 × CO2 climate sensitivity.” [Full text]

Geographical scenarios of greenhouse-gas and anthropogenic-sulfate-aerosol induced climate changes – Schlesinger et al. (1997) (Climate Research Group Report, Department of Atmospheric Sciences, University of illinois at Urbana Champaign, Urbana, IL, USA)

Sensitivity of Simulated Global Climate to Perturbations in Low-Cloud Microphysical Properties. Part I: Globally Uniform Perturbations – Chen & Ramaswamy (1996) “The sensitivity of the global climate to perturbations in the microphysical properties of low clouds is investigated using a general circulation model coupled to a static mixed layer ocean with fixed cloud distributions and incorporating a new broadband parameterization for cloud radiative properties. … The model’s climate sensitivity (ratio of global-mean surface temperature response to the global-mean radiative forcing) is virtually independent (to 10%) of the sign, magnitude, and the spatial pattern of the forcings considered, thus revealing a linear and invariant nature of the model’s global-mean response.” [Full text]

The Effect of Enhanced Greenhouse Warming on Winter Cyclone Frequencies and Strengths – Lambert (1995) “The extratropical winter cyclone climatologies for the Northern and Southern Hemispheres are presented for a control, or 1 × CO2 simulation, and an enhanced greenhouse warming, or 2 × CO2 simulation, using the second generation Canadian Climate Centre general circulation model.” [Full text]

A Global Climate Model (GENESIS) with a Land-Surface Transfer Scheme (LSX). Part II: CO2 Sensitivity – Thompson & Pollard (1995) “The sensitivity of the equilibrium climate to doubled atmospheric CO2 is investigated using the GENESIS global climate model version 1.02. … The global annual surface-air warming in the model is 2.1°C, with global precipitation increasing by 3.3%.” [Full text]

Response of the Météo-France climate model to changes in CO2 and sea surface temperature – Mahfouf et al. (1993) “The climate response to an increase in carbon dioxide and sea surface temperatures is examined using the Météo-France climate model. … A 5-year simulation is performed with a doubled CO2 concentration using, as lower boundary conditions, mean surface temperatures anomalies and sea ice limits predicted for the years 56–65 of a 100-year transient simulation performed at Hamburg with a global coupled atmosphere-ocean model. The perturbed simulation produces a global mean surface air warming of 1.4 K and an increase in global mean precipitation rate of 4%.”

Century-scale effects of increased atmospheric CO2 on the ocean-atmosphere system – Manabe & Stouffer (1993) “A coupled ocean-atmosphere climate model is presently used to project the evolution of the world’s climate over the course of several centuries characterized by (1) a doubling and (2) a quadrupling of atmospheric CO2. Global mean surface air temperature increases of 3.5 and 7 percent, respectively, are seen over a period of 500 years; these projections are respectively associated with sea level rises of 1 and 2 m apart from ice-sheet melting, which would make the figures much larger.”

Greenhouse Gas–induced Climate Change Simulated with the CCC Second-Generation General Circulation Model – Boer et al. (1992) “The Canadian Climate Centre second-generation atmospheric general circulation model coupled to a mixed-layer ocean incorporating thermodynamic sea ice is used to simulate the equilibrium climate response to a doubling of C02. … The results of the simulation indicate a global annual warming of 3.5°C with enhanced warming found over land and at higher latitudes.” [Full text]

Deriving global climate sensitivity from palaeoclimate reconstructions – Hoffert & Covey (1992) “Here we retrieve the sensitivity of two palaeoclimates, one colder and one warmer than present, by independently reconstructing both the equilibrium surface tem-perature change and the radiative forcing. Our results yield ΔT2x = 2.3 ±0.9 °C. This range is comparable with estimates from GCMs and inferences from recent temperature observations and ocean models.”

The Response of the BMRC AGCM to a Doubling of CO2 – McAvaney et al. (1991) (BMRC Technical Memorandum No. 3)

Sensitivity of the equilibrium surface temperature of a GCM to systematic changes in atmospheric carbon dioxide – Oglesby & Saltzman (1990) “The equilibrium response of surface temperature to atmospheric CO2 concentration, for six values between 100 and 1000 ppm, is calculated from a series of general circulation model experiments. This response is nonlinear, showing greater sensitivity for lower values of CO2 than for the higher values. It is suggested that changes in CO2 concentration of a given magnitude (e.g., 100 ppm) play a larger role in the Pleistocene ice age type temperature variations, than in causing global temperature changes due to anthropogenic increases.”

C02 and climate: a missing feedback? – Mitchell & Ingram (1989) “Here we report results of simulations that indicate that the changes of state of cloud water may provide a substantial negative feedback on climate. The feedback is concen-trated in mid-latitudes and affects both the magnitude and distribu-tion of the climate change expected from increases in ‘greenhouse’ gases. Improved measurements and parameterizations of cloud processes are needed to quantify this process.”

The effect of doubling the CO 2 concentration on convective and non-convective rainfall in a general circulation model coupled with a simple mixed layer ocean – Noda & Tokioka (1989) (Journal of the Meteorological Society of Japan, 67, 95-110)

Design and Critical Appraisal of an Accelerated Integration Procedure for Atmospheric GCM/Mixed-Layer Ocean Models – Schlesinger et al. (1989) “The AIP was used for 1 × CO2 and 2 × CO2 simulations with the OSU AGCM/mixed-layer Oman model.” [Full text]

Climate sensitivity due to increased CO2: experiments with a coupled atmosphere and ocean general circulation model – Washington & Meehl (1989) “Three simulations are run: one with an instantaneous doubling of atmospheric CO2 (from 330 to 660 ppm), another with the CO2 concentration starting at 330 ppm and increasing linearly at a rate of 1% per year, and a third with CO2 held constant at 330 pm. Results at the end of 30 years of simulation indicate a globally averaged surface air temperature increase of 1.6° C for the instantaneous doubling case…”

Cloud Feedback Processes in a General Circulation Model – Wetherald & Manabe (1988) “The influence of the cloud feedback process upon the sensitivity of climate is investigated by comparing the behavior of two versions of a climate model with predicted and prescribed cloud cover. … At most latitudes the effect of reduced cloud amount in the upper troposphere overshadows that of increased cloudiness around the tropopause, thereby lowering the global mean planetary albedo and enhancing the CO2 induced warming. On the other hand, the increase of low cloudiness in high latitudes raises the planetary albedo and thus decreases the CO2 induced warming of climate. However, the contribution of this negative feedback process is much smaller than the effect of the positive feedback process involving the change of high cloud.” [Full text]

Simulated climate and CO2—Induced climate change over Western Europe – Wilson & Mitchell (1987) “When atmospheric CO2 concentrations are quadrupled, and sea surface temperatures and sea ice extents changed appropriately, the number of cold episodes is reduced and precipitation is less frequent in summer and autumn over much of Europe, and throughout the year in the south.”

An investigation of cloud cover change in response to thermal forcing – Wetherald & Manabe (1986) “This article reviews the distributions of cloud cover change from several climate sensitivity experiments conducted at the Geophysical Fluid Dynamics Laboratory of NOAA (GFDL) and other institutions. … It was found that in all five cases, clouds were decreased in the moist, convectively active regions such as the tropical and middle latitude rainbelts, whereas they increased in the stable region near the model surface from middle to higher latitudes. In addition, cloud also increased in the lower model stratosphere and generally decreased in the middle and upper troposphere for practically all latitudes.”

Volcanic, CO2 and solar forcing of Northern and Southern Hemisphere surface air temperatures – Gilliland & Schneider (1984) “The model used here allows a direct comparison of observed and simulated temperatures from the same physical domains—over land and sea separately in each hemisphere. … The empirically derived CO2 equilibrium doubling response for air surface temperature is 1.6 +/- 0.3°C, although the statistical significance of this result is uncertain.”

Climate sensitivity: Analysis of feedback mechanisms – Hansen et al. (1984) “We study climate sensitivity and feedback processes in three independent ways: (1) by using a three dimensional (3-D) global climate model for experiments in which solar irradiance So is increased 2 percent or CO2 is doubled, (2) by using the CLIMAP climate boundary conditions to analyze the contributions of different physical processes to the cooling of the last ice age (18K years ago), and (3) by using estimated changes in global temperature and the abundance of atmospheric greenhouse gases to deduce an empirical climate sensitivity for the period 1850-1980. … Our 3-D global climate model yields a warming of ~4°C for either a 2 percent increase of So or doubled CO2. … The temperature increase believed to have occurred in the past 130 years (approximately 0.5°C) is also found to imply a climate sensitivity of 2.5-5°C for doubled Cog…” [Full text]

Seasonal Cycle Experiment on the Climate Sensitivity Due to a Doubling of CO2 With an Atmospheric General Circulation Model Coupled to a Simple Mixed-Layer Ocean Model – Washington & Meehl (1984) “A simple slab ocean of 50 m depth, which allows for seasonal ocean heat storage but no ocean heat transport, is coupled to a global spectral general circulation model with global domain, realistic geography, and computed clouds. Globally averaged, the annual mean surface air temperature increase computed over the last 3 years of an integration with a full annual cycle for 2 × CO2 compared to the control for 1 × CO2 is 3.5°C.”

Climate Studies with a Multi-Layer Energy Balance Model. Part II: The Role of Feedback Mechanisms in the CO2 Problem – Chou et al. (1982) “The sensitivity of climate to a doubling of the atmospheric CO2, content has been studied using the GLAS multi-layer energy balance model. In response to a doubled CO2 content, tropospheric temperature lapse rate decreases at low latitudes but increases at high latitudes. Averaged over the Northern Hemisphere, the change is +2.3°C in the surface temperature and +0.47°C in the earth’s brightness temperature. … It is found that the sensitivity of surface temperature is approximately doubled at all latitudes due to the change in water vapor content.” [Full text]

Sensitivity Analysis of a Radiative-Convective Model by the Adjoint Method – Hall et al. (1982) “The adjoint method of sensitivity analysis is demonstrated on a radiative-convective climate model. … The sensitivities accurately predict the effect on surface air temperature of small variations in the model parameters. Relative sensitivities are used to rank the importance of all the parameters. Several of the sensitivities to parameters customarily considered in previous works (e.g., solar constant, surface albedo, relative humidity, CO2 concentration) are reproduced, but the largest sensitivities are to constants used to compute the saturation vapor pressure of water.” [Full text]

Impact of coupled perturbations of atmospheric trace gases on Earth’s climate and ozone – Nicoli & Visconti (1982) “The doubling of carbon dioxide concentration has the effect of warming the troposphere and cooling the stratosphere. As a result of this cooling, the change of ozone columnar density produced by 10 ppb of chlorine amount to 9.3% as compared to –10.9% obtained without temperature feedback. Perturbation in nitrous oxide correspond to an increase in NO x of the stratosphere with consequent ozone reduction while doubling the methane concentration correspond to a slight increase in columnar density. The effect of the increased methane concentration in the stratosphere contributes to reduce the effect of CFC due to the enhanced formation of HCl. The perturbation of these two minor constituents appreciably increase the greenhouse effect to 2.30 from 1.67°, obtained when carbon dioxide alone is considered.”

The Role of Ocean-Atmosphere Interactions in the CO2 Climate Problem – Ramanathan (1981) “The climate sensitivity question is examined from the viewpoint of surface energy balance considerations. This approach clarifies the role of ocean-atmosphere interactions in determining the surface warming to an increase in CO2. The study uses a one-dimensional, 17-layer, coupled ocean-atmosphere model. The primary contribution to the surface warming is from the enhanced tropospheric IR emission, which is an order of magnitude greater than the direct CO2 radiative heating at the surface. The source for this enhancement is the increased H2O evaporation from the warmer oceans in the CO2 rich atmosphere and, hence, ocean-atmosphere interactions play a crucial role in determining the magnitude of the surface warming as well as its transient response.” [Full text]

On the Distribution of Climate Change Resulting from an Increase in CO2 Content of the Atmosphere – Manabe & Wetherald (1980) “A study of the climatic effect of doubling or quadrupling of CO2 in the atmosphere has been continued by the use of a simple general circulation model with a limited computational domain, highly idealized geography, no seasonal variation of insolation, and a simplified interaction between cloud and radiative transfer. The results from the numerical experiments reveal that the response of the model climate to an increase of CO2 content in air is far from uniform geographically.” [Full text]

The Climatological Significance of a Doubling of Earth’s Atmospheric Carbon Dioxide Concentration – Idso (1980) “The mean global increase in thermal radiation received at the surface of the earth as a consequence of a doubling of the atmospheric carbon dioxide content is calculated to be 2.28 watts per square meter. Multiplying this forcing function by the atmosphere’s surface air temperature response function, which has recently been determined by three independent experimental analyses to have a mean global value of 0.113 K per watt per square meter, yields a value of <= 0.26 K for the resultant change in the mean global surface air temperature. This result is about one order of magnitude less than those obtained from most theoretical numerical models, but it is virtually identical to the result of a fourth experimental approach to the problem described by Newell and Dopplick.”

A CO2-climate sensitivity study with a mathematical model of the global climate – Manabe & Stouffer (1979) “An increase in the CO2-content of the atmosphere resulting from man’s activity could have a significant effect on the climate in the near future. We describe here some new results from a study of the response of a mathematical model of the climate to an increase in the CO2 content of the air.”

Some Experiments with a Zonally Averaged Climate Model – Ohring & Adler (1978) “When the atmospheric carbon dioxide content is doubled, the hemispheric mean surface temperature increases by 0.5°C in the absence of ice feedback, the largest increases taking place at high latitudes. Ice albedo feedback amplifies the hemispheric average temperature change by about 50%; amplifications as large as several hundred percent are obtained in polar regions. A change in mean surface temperature of ±1°C for a ±1% change in solar constant is obtained in the absence of ice feedback, but this is amplified to −1.5°C (decreased solar constant) and 1.4°C (increased solar constant) when ice feedback is included. As In the 2×CO2 case, polar amplification factors due to ice albedo feedback are several hundred percent.” [Full text]

A Radiative-Convective Model Study of the CO2 Climate Problem – Augustsson & Ramanathan (1977) “A radiative-convective model study of the increase in global surface temperature ΔTg due to an increase in the CO2 concentration is presented. … The computed value of ΔTg is very sensitive to radiative-convective model assumptions regarding cloud top and relative humidity. Because of this sensitivity the estimated value of ΔTg for a doubling of the CO2 concentration ranges from 1.98 to 3.2 K.” [Full text]

An Annual Zonally Averaged Hemispherical Climatic Model with Diffuse Cloudiness Feedback – Temkin & Snell (1976) “An annual, zonally averaged, steady-state hemispherical climatic model is developed which incorporates the diffuse thin cloud tropospheric structure of Weare and Snell as a cloudiness feedback mechanism. … The response of the model to variations in various climatic determinants is studied, including hemispherical variations in carbon dioxide, aerosol and solar constant, and also including certain zonal variations in man-made thermal energy and aerosol. … The sensitivity of the model in terms of the hemispherical mean sea level temperature is about twice that of the globally averaged model of Weare and Snell.” [Full text]

The dependence of atmospheric temperature on the concentration of carbon dioxide – Manabe (1975) A book chapter. “The effect of changes in the carbon dioxide content of the atmosphere on the average world temperature is investigated using a radiative, convective model of the atmosphere (Manabe et al., 1964, 1967). The radiative, convective equilibrium of the atmosphere obtained with the model is in good agreement with the distribution given by the U.S. standard atmosphere. Numerical computations indicate that doubling or halving the atmospheric CO2 concentration increases or decreases the surface temperature of the atmosphere by about 2.3 deg C. Assuming a 25% increase from the 1900 concentration by the end of this century, a corresponding 0.8 deg C increase in average surface temperature is predicted.”

The Effects of Doubling the CO2 Concentration on the climate of a General Circulation Model – Manabe & Wetherald (1975) “An attempt is made to estimate the temperature changes resulting from doubling the present CO2 concentration by the use of a simplified three-dimensional general circulation model. … It is shown that the CO2 increase raises the temperature of the model troposphere, whereas it lowers that of the model stratosphere.” [Full text]

A study of the sensitivity of radiativeconvective models – Ramanathan (1975) (Preprints Second Conf. Atmospheric Radiation, 1975) This probably is the referred Ramanathan (1975).

A Reassessment of the Effect of CO2 Variations on a Simple Global Climatic Model – Sellers (1974) “A simple global climatic model described earlier is modified slightly and reapplied to the CO2 problem. … …the average global surface temperature drops 1.64C if the amount of CO2 in the atmosphere is halved and rises 1.32C if the amount is doubled.” [Full text]

A Diffuse Thin Cloud Atmospheric Structure as a Feedback Mechanism in Global Climatic Modeling – Weare & Snell (1974) “The sensitivity of the “climate” to variations in aerosol optical density, atmospheric carbon dioxide, and the solar constant is calculated and the results are comparable to those obtained by others using very different models. In general, our model exhibits slightly greater stability.” [Full text]

A New Global Climatic Model – Sellers (1973) “The initial carbon dioxide content of the atmosphere (250 cm) was doubled and halved without any appreciable effect on surface temperatures. Doubling the CO2 content increased the temperature by at most 0.6C (at high northern latitudes in winter); the average increase was only 0.1C.” [Full text]

Estimates of future change of climate due to the increase of carbon dioxide concentration in the air – Manabe (1971) (Man’s Impact on the Climate, W. I-I. Matthews, W. W. Kellogg, and G. D. Robinson, Eds., Cambridge, MA: The MIT Press, 249-264)

Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate – Rasool & Schneider (1971) “Effects on the global temperature of large increases in carbon dioxide and aerosol densities in the atmosphere of Earth have been computed. It is found that, although the addition of carbon dioxide in the atmosphere does increase the surface temperature, the rate of temperature increase diminishes with increasing carbon dioxide in the atmosphere.”

Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity – Manabe & Wetherald (1967) “Radiative convective equilibrium of the atmosphere with a given distribution of relative humidity is computed as the asymptotic state of an initial value problem. … According to our estimate, a doubling of the CO2 content in the atmosphere has the effect of raising the temperature of the atmosphere (whose relative humidity is fixed) by about 2C. Our model does not have the extreme sensitivity of atmospheric temperature to changes of CO2 content which was adduced by Möller.” [Full text]

On the Influence of Changes in the CO2 Concentration in Air on the Radiation Balance of the Earth’s Surface and on the Climate – Möller (1963) (J. Geophysical Research 68, 3877-3886) Is missing from JGR digital library.

The carbon dioxide theory of climate change – Plass (1956) “The most recent calculations of the infra-red flux in the region of the 15 micron CO2 band show that the average surface temperature of the earth increases 3.6° C if the CO2 concentration in the atmosphere is doubled and decreases 3.8° C if the CO2 amount is halved, provided that no other factors change which influence the radiation balance.” [Full text]

The Artificial Production of Carbon Dioxide and Its Influence on Climate – Callendar (1938) (Quarterly J. Royal Meteorological Society 64, 223-40)

The Temperature of the Lower Atmosphere of the Earth – Hulburt (1931) “From the known amounts of the various gases of the atmosphere from sea level to about 20 km, from the observed light absorption coefficients of the gases and from the albedo of the earth’s surface the temperature of the atmosphere in radiative equilibrium is calculated on the assumption that the sunlight is the only source of energy. … Calculation shows that doubling or tripling the amount of the carbon dioxide of the atmosphere increases the average sea level temperature by about 4° and 7°K, respectively; halving or reducing to zero the carbon dioxide decreases the temperature by similar amounts. Such changes in temperature are about the same as those which occur when the earth passes from an ice age to a warm age, or vice versa. Thus the calculation indicates that the carbon dioxide theory of the ice ages, originally proposed by Tyndall, is a possible theory.”

On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground – Arrhenius (1896) “Thus if the quantity of carbonic acid increases in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression.” [Full text]

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Wrong trend

Posted by Ari Jokimäki on November 2, 2009

Hey, this is wrong way around!


In this particular occasion (today’s situation just few minutes ago), there is 32 paperlist views and 9 clicks to papers. This is quite common situation. The paperlists in this blogs are just lists of links to scientific papers. I’m not even giving full abstracts in the lists, just a few selected sentences.

So click those links, dear readers. 🙂

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