AGW Observer

Observations of anthropogenic global warming

New research from last week 42/2012

Posted by Ari Jokimäki on October 22, 2012

This week’s papers look into rice growth, ice sheet temperature response, invasive species, Greenland temperatures, global warming trends, carbon dioxide emissions, sea level, solar forcing, ozone depletion, ski tourism, tropopause, and sea ice vs. winter climate.

Link between Arctic sea ice reduction and cold winters in Europe

Trends Arctic sea ice reduction and European cold winters in CMIP5 climate change experiments – Yang & Christensen (2012)

Abstract: “European winter climate and its possible relationship with the Arctic sea ice reduction in the recent past and future as simulated by the models of the Climate Model Intercomparison Project phase 5 (CMIP5) is investigated, with focus on the cold winters. While Europe will warm overall in the future, we find that episodes of cold months will continue to occur and there remains substantial probability for the occurrence of cold winters in Europe linked with sea ice reduction in the Barents and Kara Sea sector. A pattern of cold-European warm-Arctic anomaly is typical for the cold events in the future, which is associated with the negative phase of the Arctic Oscillation. These patterns, however, differ from the corresponding patterns in the historical period, and underline the connection between European cold winter events and Arctic sea ice reduction.”

Citation: Yang, S. and J. H. Christensen (2012), Arctic sea ice reduction and European cold winters in CMIP5 climate change experiments, Geophys. Res. Lett., 39, L20707, doi:10.1029/2012GL053338.

Tropopause is getting thicker

Trends in the global tropopause thickness revealed by radiosondes – Feng et al. (2012)

Abstract: “The first global trends in the thickness of the tropopause layer (TL) are analyzed based on radiosonde data in the Integrated Global Radiosonde Archive (IGRA) for the period of 1965–2004. It reveals that TL has been thickening for the entire globe with positive trends of 0.16 ± 0.12 km/decade during this period. Statistically significant thickening is observed in the tropics, North Hemisphere (NH) extratropics, and NH poles. Accompanied by overall cooling of −0.58 ± 0.40 K/decade in TL’s top, remarkable rising trends of 0.35 ± 0.29 km/decade are observed in the correspoding height. However, the anti-correlation of the trends in the tropopause temperature and the corresponding height is not observed in its lower boundary, namely the first lapse rate tropopause (LRT), for all the latitude bands as suggested by the previous studies. The results imply that the temperature of the TL is primarily couple with the height of its upper boundary as the thickness of the TL is more correlated with the temperature of the lower stratosphere than with the tempeature of the upper troposphere. Long-term changes in TL may in turn carry more information how tropopause change in response to climate change than in the sharp “tropopause surface” only.”

Citation: Feng, S., Y. Fu, and Q. Xiao (2012), Trends in the global tropopause thickness revealed by radiosondes, Geophys. Res. Lett., 39, L20706, doi:10.1029/2012GL053460.

How climate change affects Australian ski tourism flow to New Zealand

Climate change in a regional context: relative vulnerability in the Australasian skier market – Hopkins et al. (2012)

Abstract: “The concept of relative vulnerability allows for comparisons between analogous units in a regional context. It is utilised within tourism studies to consider how climate change might affect demand and perceived attractiveness of destinations relative to their competitors. This paper examines Australian tourists travelling to New Zealand’s ski fields, responding to the intergovernmental panel on climate change (IPCC) assertion that, “tourist flows from Australia to New Zealand might grow as a result of the relatively poorer snow conditions in Australia” (Hennessy et al. 2007: p 523). This travel flow is not a new phenomenon; however, it is forecast to increase as climate change impacts upon Australia’s natural and man-made snowmaking capacity with implications for the viability of the ski industries in both Australia and New Zealand. The Queenstown Lakes Region (South Island, New Zealand) serves as the field area for this study. The empirical research utilises a qualitative methodology for which in-depth, semi-structured interviews were conducted with New Zealand ski industry representatives and Australian tourists during the southern hemisphere winter season of 2011. Findings suggest that the social context of vulnerability creates difficulty in forecasting the outcomes and behaviours associated with relative vulnerability. While tourism representatives’ focus on snow reliability and availability to conceptualise relative vulnerability, Australian tourists are influenced by a broader range of factors including their own travel experience. This paper demonstrates a clear need to move beyond a focus on snow reliability to consider the broad range of factors that contribute to regional variations in vulnerability. In doing so, it confirms the critical importance of situating relative vulnerability within a social context.”

Citation: Debbie Hopkins, James E. S. Higham and Susanne Becken, Regional Environmental Change, 2012, DOI: 10.1007/s10113-012-0352-z.

Stratospheric ozone depletion warms Antarctic surface and ocean

Antarctic climate response to stratospheric ozone depletion in a fine resolution ocean climate model – Bitz & Polvani (2012) [FULL TEXT]

Abstract: “We investigate the impact of stratospheric ozone depletion on Antarctic climate, paying particular attention to the question of whether eddy parameterizations in the ocean fundamentally alter the results. This is accomplished by contrasting two versions of the Community Climate System Model (version 3.5), one at 0.1° ocean and sea ice resolution and the other at 1° with parameterized ocean eddies. At both resolutions, pairs of integrations are performed: one with high (1960) and one with low (2000) ozone levels. We find that the effect of ozone depletion is to warm the surface and the ocean to a depth of 1000 m and to significantly reduce the sea ice extent. While the ocean warming is somewhat weaker when the eddies are resolved, the total loss of sea ice area is roughly the same in the fine and coarse resolution cases.”

Citation: Bitz, C. M. and L. M. Polvani (2012), Antarctic climate response to stratospheric ozone depletion in a fine resolution ocean climate model, Geophys. Res. Lett., 39, L20705, doi:10.1029/2012GL053393.

Solar forcing of climate during last millennium in northern Sweden

Solar forcing of climate during the last millennium recorded in lake sediments from northern Sweden – Kokfelt & Muscheler (2012)

Abstract: “We report on a sediment record from a small lake within the subarctic wetland complex Stordalen in northernmost Sweden covering the last 1000 years. Variations in the content of minerogenic material are found to follow reconstructed variations in the activity of the Sun between the 13th and 18th centuries. Periods of low solar activity are associated with minima in minerogenic material and vice versa. A comparison between the sunspot cycle and a long instrumental series of summer precipitation further reveals a link between the 11 yr solar cycle and summer precipitation variability since around 1960. Solar minima are in this period associated with minima in summer precipitation, whereas the amount of summer precipitation increases during periods with higher solar activity. Our results suggest that the climate responds to both the 11 yr solar cycle and to long-term changes in solar activity and in particular solar minima, causing dry conditions with resulting decreased runoff.”

Citation: U Kokfelt, R Muscheler, The Holocene October 18, 2012 0959683612460781, doi: 10.1177/0959683612460781.

New study suggests 0.25 m increase to upper bound of sea level rise by 2100

Toward a physically plausible upper bound of sea-level rise projections – Sriver et al. (2012)

Abstract: “Anthropogenic sea-level rise (SLR) causes considerable risks. Designing a sound SLR risk-management strategy requires careful consideration of decision-relevant uncertainties such as the reasonable upper bound of future SLR. The recent Intergovernmental Panel on Climate Change’s (IPCC) Fourth Assessment reported a likely upper SLR bound in the year 2100 near 0.6 m (meter). More recent studies considering semi-empirical modeling approaches and kinematic constraints on glacial melting suggest a reasonable 2100 SLR upper bound of approximately 2 m. These recent studies have broken important new ground, but they largely neglect uncertainties surrounding thermal expansion (thermosteric SLR) and/or observational constraints on ocean heat uptake. Here we quantify the effects of key parametric uncertainties and observational constraints on thermosteric SLR projections using an Earth system model with a dynamic three-dimensional ocean, which provides a mechanistic representation of deep ocean processes and heat uptake. Considering these effects nearly doubles the contribution of thermosteric SLR compared to previous estimates and increases the reasonable upper bound of 2100 SLR projections by 0.25 m. As an illustrative example of the effect of overconfidence, we show how neglecting thermosteric uncertainty in projections of the SLR upper bound can considerably bias risk analysis and hence the design of adaptation strategies. For conditions close to the Port of Los Angeles, the 0.25 m increase in the reasonable upper bound can result in a flooding-risk increase by roughly three orders of magnitude. Results provide evidence that relatively minor underestimation of the upper bound of projected SLR can lead to major downward biases of future flooding risks.”

Citation: Ryan L. Sriver, Nathan M. Urban, Roman Olson and Klaus Keller, Climatic Change, 2012, DOI: 10.1007/s10584-012-0610-6.

Fraction of natural area can be used as a proxy for urban carbon dioxide emissions

Fraction of natural area as main predictor of net CO2 emissions from cities – Nordbo et al. (2012)

Abstract: “Cities account for most anthropogenic greenhouse-gas emissions, CO2 being most important. We evaluate the net urban contribution to CO2 emissions by performing a meta-analysis of all available 14 annual CO2 budget studies. The studies are based on direct flux measurements using the eddy-covariance technique which excludes all strong point sources. We show that the fraction of natural area is the strongest predictor of urban CO2 budgets, and this fraction can be used as a robust proxy for net urban CO2 emissions. Up-scaling, based on that proxy and satellite mapping of the fraction of natural area, identifies urban hotspots of CO2 emissions; and extraction of 56 individual cities corroborates their inventory-based estimates. Furthermore, cities are estimated as carbon-neutral when the natural fraction is about 80%. This fresh view on the importance of cities in climate change treats cities as urban ecosystems: incorporating natural areas like vegetation.”

Citation: Nordbo, A., L. Jarvi, S. Haapanala, C. R. Wood, and T. Vesala (2012), Fraction of natural area as main predictor of net CO2 emissions from cities, Geophys. Res. Lett., doi:10.1029/2012GL053087.

Anthropogenic global warming trend has been remarkably steady and statistically significant for the past 100 years

Deducing Multi-decadal Anthropogenic Global Warming Trends Using Multiple Regression Analysis – Zhou & Tung (2012)

Abstract: “In order to unmask the anthropogenic global warming trend imbedded in the climate data, multiple linear regression analysis is often employed to filter out short-term fluctuations caused by El Nino-Southern Oscillation (ENSO), volcano aerosols and solar forcing. These fluctuations are unimportant as far as their impact on the deduced multidecadal anthropogenic trends is concerned: ENSO and volcano aerosols have very little multi-decadal trend. Solar variations do have a secular trend, but it is very small and uncertain. What is important, but is left out of all multiple regression analysis of global warming so far, is a long-perioded oscillation called the Atlantic Multi-decadal Oscillation (AMO). When the AMO Index is included as a regressor (i.e. explanatory variable), the deduced multi-decadal anthropogenic global warming trend is so impacted that previously deduced anthropogenic warming rates need to be substantially revised. The deduced net anthropogenic global warming trend has been remarkably steady and statistically significant for the past 100 years.”

Citation: Jiansong Zhou and Ka-Kit Tung, Journal of the Atmospheric Sciences 2012.

Current warming in northern Greenland is unprecedented in the past 2400 years

Twentieth-century warming revives the world’s northernmost lake – Perren et al. (2012)

Abstract: “Although recent ecological changes are widespread in Arctic lakes, it remains unclear whether they are more strongly associated with climate warming or the deposition of reactive nitrogen (Nr) from anthropogenic sources. We developed a 3500-yr paleolimnological record from the world’s northernmost lake to explore this question. Microfossils indicate that siliceous diatoms and chrysophytes were abundant initially, but disappeared 2400 yr ago in concert with Neoglacial cooling. Microfossils reappear in 20th-century sediments and reach unprecedented concentrations in sediments deposited after ca. A.D. 1980, tracking increasing summer temperatures in the absence of evidence for atmospheric nutrient subsidies. These results indicate that current warming in northern Greenland is unprecedented in the context of the past 2400 yr, and that climate change alone is responsible for the marked biological changes observed.”

Citation: Bianca B. Perren, Alexander P. Wolfe, Colin A. Cooke, Kurt H. Kjær, David Mazzucchi and Eric J. Steig, Geology, v. 40 no. 11 p. 1003-1006, doi: 10.1130/G33621.1.

Climate change effects on invasive species versus native species

Poised to prosper? A cross-system comparison of climate change effects on native and non-native species performance – Sorte et al. (2012) [FULL TEXT]

Abstract: “Climate change and biological invasions are primary threats to global biodiversity that may interact in the future. To date, the hypothesis that climate change will favour non-native species has been examined exclusively through local comparisons of single or few species. Here, we take a meta-analytical approach to broadly evaluate whether non-native species are poised to respond more positively than native species to future climatic conditions. We compiled a database of studies in aquatic and terrestrial ecosystems that reported performance measures of non-native (157 species) and co-occurring native species (204 species) under different temperature, CO2 and precipitation conditions. Our analyses revealed that in terrestrial (primarily plant) systems, native and non-native species responded similarly to environmental changes. By contrast, in aquatic (primarily animal) systems, increases in temperature and CO2 largely inhibited native species. There was a general trend towards stronger responses among non-native species, including enhanced positive responses to more favourable conditions and stronger negative responses to less favourable conditions. As climate change proceeds, aquatic systems may be particularly vulnerable to invasion. Across systems, there could be a higher risk of invasion at sites becoming more climatically hospitable, whereas sites shifting towards harsher conditions may become more resistant to invasions.”

Citation: Cascade J. B. Sorte, Ines Ibáñez, Dana M. Blumenthal, Nicole A. Molinari, Luke P. Miller, Edwin D. Grosholz, Jeffrey M. Diez, Carla M. D’Antonio, Julian D. Olden, Sierra J. Jones, Jeffrey S. Dukes, Ecology Letters, DOI: 10.1111/ele.12017.

Lagged ice-margin temperature response of Greenland ice sheet implies that significant retreat may be yet to come

Maximum late Holocene extent of the western Greenland Ice Sheet during the late 20th century – Kelley et al. (2012)

Abstract: “The pattern of Greenland Ice Sheet margin change during the 20th century is variable. Large-scale retreat of marine-outlet glaciers contrasts with the often-negligible retreat observed along land-terminating margins of the ice sheet. We reconstruct a chronology of ice-margin change for two land-terminating ice margins in western Greenland using radiocarbon and 10Be exposure dating. Our results indicate that two land-terminating lobes attained their maximum late Holocene position in the late 20th century. This contrasts with the nearby marine-terminating Jakobshavn Isbræ, which achieved a maximum late Holocene position during the Little Ice Age, and has since retreated ca 40 km. In addition, we survey ice-margin change across western Greenland, utilizing satellite imagery. We find that many land-terminating sectors of the ice sheet, in addition to our study area, may have attained their maximum late Holocene extent during the 20th century. This suggests a lagged ice-margin response to prior cooling, such as the Little Ice Age, which would imply significant retreat of land-terminating sections of the Greenland Ice Sheet in response to 20th and 21st century warming may be yet to come.”

Citation: Samuel E. Kelley, Jason P. Briner, Nicolás E. Young, Gregory S. Babonis, Bea Csatho, Quaternary Science Reviews, Volume 56, 21 November 2012, Pages 89–98,

Major temperature-induced change of the rice growth duration is underway in China

Climate warming over the past three decades has shortened rice growth duration in China and cultivar shifts have further accelerated the process for late rice – Zhang et al. (2012)

Abstract: “An extensive dataset on rice phenology in China, including 202 series broadly covering the past three decades (1980s–2000s), was compiled. From these data, we estimated the responses of growth duration length to temperature using a regression model based on the data with and without de-trending. Regression coefficients derived from the de-trended data reflect only the temperature effect, whereas those derived from data without de-trending represent a combined effect of temperature and confounding cultivar shifts. Results indicate that the regression coefficients calculated from the data with and without de-trending show an average shortening of the growth duration of 4.1 to 4.4 days for each additional increase in temperature over the full growth cycle. Using the de-trended data, 95.0% of the data series exhibited a negative correlation between the growth duration length and temperature; this correlation was significant in 61.9% of all of the data series. We then compared the difference between the two regression coefficients calculated from data with and without de-trending and found a significantly greater temperature sensitivity using the data without de-trending (-2.9 days °C-1) than that derived from the de-trended data (-2.0 days °C-1) in the period of emergence to heading for the late rice, producing a negative difference in temperature sensitivity (-0.9 days °C-1). This implies that short-duration cultivars were planted with increase in temperature and exacerbated the undesired phenological change. In contrast, positive differences were detected for the single (0.6 days °C-1) and early rice (0.5 days °C-1) over the full growth cycle, which might indicate long-duration cultivars were favoured with climate warming, but these differences were insignificant. In summary, our results suggest that a major, temperature-induced change of the rice growth duration is underway in China and that using a short-duration cultivar has been accelerating the process for late rice.”

Citation: Tianyi Zhang, Yao Huang, Xiaoguang Yang, Global Change Biology, DOI: 10.1111/gcb.12057.

Other studies from last week

The Reversibility of Sea Level Rise – Bouttes et al. (2012)

The tropical precipitation response to orbital precession – Merlis et al. (2012)

Regional changes in wind energy potential over Europe using regional climate model ensemble projections – Hueging et al. (2012)

Observed Tropospheric Temperature Response to 11-Year Solar Cycle, And What It Reveals About Mechanisms – Zhou & Tung (2012)

How well do climate models simulate cloud vertical structure? A comparison between CALIPSO-GOCCP satellite observations and CMIP5 models – Cesana & Chepfer (2012)

A fifty year record of winter glacier melt events in southern Chile, 38°–42°S – Brock et al. (2012) [FULL TEXT]

Is a Transition to Semi-Permanent Drought Conditions Imminent in the U.S. Great Plains? – Hoerling et al. (2012)

Seasonal changes in solar radiation and relative humidity in Europe in response to global warming – Ruosteenoja & Räisanen (2012)

On the linear additivity of climate forcing-response relationships at global and continental scales – Shiogama et al. (2012)

Alpine snow cover in a changing climate: a regional climate model perspective – Steger et al. (2012)

The response of methane and nitrous oxide fluxes to forest change in Europe – Gundersen et al. (2012) [FULL TEXT]

Approaches for inclusion of forest carbon cycle in life cycle assessment – a review – Helin et al. (2012)

Radiative budget and cloud radiative effect over the Atlantic from ship-based observations – Kalisch & Macke (2012) [FULL TEXT]

Global runoff anomalies over 1993–2009 estimated from coupled Land–Ocean–Atmosphere water budgets and its relation with climate variability – Munier et al. (2012) [FULL TEXT]

High-resolution interpolar difference of atmospheric methane around the Last Glacial Maximum – Baumgartner et al. (2012) [FULL TEXT]

Uncertainty in the ENSO amplitude change from the past to the future – Watanabe et al. (2012)

How tillite weathering during the snowball Earth aftermath induced cap carbonate deposition – Fabre & Berger (2012)

The impact of the El Niño-Southern Oscillation on maximum temperature extremes – Arblaster & Alexander (2012)

Mitigation of 21st century Antarctic sea ice loss by stratospheric ozone recovery – Smith et al. (2012)

Mild Little Ice Age and unprecedented recent warmth in an 1800 year lake sediment record from Svalbard – D’Andrea et al. (2012)

Late glacial fluctuations of Quelccaya Ice Cap, southeastern Peru – Kelly et al. (2012)

Impacts of climate change on primary production and carbon sequestration of boreal Norway spruce forests: Finland as a model – Ge et al. (2012)

A 7000 year record of paleohurricane activity from a coastal wetland in Belize – McCloskey & Liu (2012)

CLASSIC OF THE WEEK: Setchell (1915)

The Law of Temperature Connected with the Distribution of the Marine Algae – Setchell (1915) [FULL TEXT]

Abstract: No abstract. First paragraph: “What I have to bring before you is simply a preliminary consideration of the general subject of the geographical dis- tribution of the marine algae together with some inquiry into the conditions immediately affecting such distribution and as possibly effecting a segregation into the larger units. In accordance with such an intention, I have started a tabula- tion of all the marine species and varieties, which is far from being completed as yet, but which has, however, reached a stage at which certain general statements may be made as to probable results.”

Citation: William Albert Setchell, Annals of the Missouri Botanical Garden, Vol. 2, No. 1/2, Anniversary Proceedings (Feb. – Apr., 1915) (pp. 287-305).

When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. Here’s the archive for the research papers of previous weeks. If this sort of thing interests you, be sure to check out A Few Things Illconsidered. They also have a weekly posting containing lots of links to new research and other climate related news.

One Response to “New research from last week 42/2012”

  1. [...] 2012/10/22: AGWObserver: New research from last week 42/2012 [...]

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