AGW Observer

Observations of anthropogenic global warming

New research from last week 8/2011

Posted by Ari Jokimäki on February 28, 2011

Here is the new research published last week. I’m not including everything that was published but just some papers that got my attention. Those who follow my Facebook page (and/or Twitter) have already seen most of these, as I post these there as soon as they are published. Here, I’ll just put them out in one batch. Sometimes I might also point out to some other news as well, but the new research will be the focus here. Here’s the archive for the news of previous weeks. By the way, if this sort of thing interests you, be sure to check out A Few Things Illconsidered, they have a weekly posting containing lots of links to new research and other climate related news. Planet 3.0 also reports new research.

Published last week:

Ocean blooming event caused by volcanic eruption

Fertilization potential of volcanic dust in the low-nutrient low-chlorophyll western North Pacific subtropical gyre: Satellite evidence and laboratory study – Lin et al. (2011) “In the western North Pacific subtropical ocean, the Anatahan volcano of the Mariana Islands erupted on 10 May 2003 for the first time in recorded history. Based on nine different types of remote sensing data provided by NASA, laboratory experiment of the Anatahan samples, and a 3-D ocean circulation model developed by the U.S. Naval Research Laboratory, the postvolcanic ocean biogeochemical response to the Anatahan eruption was explored. It was observed that soon after the eruption, the aerosol optical depth abruptly increased from the pre-eruption loading of ∼0.1 to ∼2. In the week following the eruption, a “bloom-like” patch was observed by NASA’s Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color sensor. Based on the chlorophyll a, fluorescence line height (FLH), at-sensor total radiance, and normalized water-leaving radiance data obtained by MODIS, the cause of the bloom-like patch was diagnosed. The results suggest that the patch was most likely a mixture of suspended volcanic particles and a phytoplankton bloom. FLH was found to be ∼9–17 × 10−3 mW cm−2 μm−1 sr−1 in the patch and ∼3–5 × 10−3 mW cm−2 μm−1 sr−1 in the ambient water, indicating that a 2–5-fold increase in biological activity occurred during the week following the eruption. Satellite altimetry indicated that the bloom took place in the presence of downwelling and was not a result of upwelled nutrients in this oligotrophic ocean. Analysis of satellite ocean color spectra of the bloom region found similar spectra as the reference Trichodesmium spectra. Laboratory experiments further substantiate the satellite observations which show elevated concentrations of limiting nutrients provided by the Anatahan samples, and the averaged soluble nitrate, phosphate, and Fe were 42, 3.1, and 2.0 nM, respectively. Though it was not possible to obtain in situ observations of the ocean biogeochemical responses that followed the Anatahan eruption, this study provided evidence based on remote sensing data and laboratory experiment that fertilization of volcanic aerosols occurred following this eruption in one of the most oligotrophic low-nutrient low-chlorophyll ocean deserts on Earth.” Lin, I.-I., et al. (2011), Global Biogeochem. Cycles, 25, GB1006, doi:10.1029/2009GB003758.

With climate change humans migrate to higher mountains too

Relationship between tourism demand in the Swiss Alps and hot summer air temperatures associated with climate change – Serquet & Rebetez (2011) “We quantified the impacts of hot summer air temperatures on tourism in the Swiss Alps by analysing the relationship between temperature and overnight stays in 40 Alpine resorts. Several temperature thresholds were tested to detect the relationship between them and summer tourism. Our results reveal significant correlations between the number of nights spent in mountain resorts and hot temperatures at lower elevations. The relationship between hot temperatures and overnight stays is more important in June and to a lesser extent in August than in July. This is probably because holidays and the peak of domestic tourist demand in summer usually take place between the beginning of July and mid-August so that long-term planned stays dominate more during these months compared to June. The alpine resorts nearest to cities are most affected by hot temperatures. This is probably because reactions to hot episodes take place on a short-term basis as heat waves remain relatively rare. Our results suggest that alpine tourist resorts could benefit from hotter temperatures at lower elevations under future climates. Tourists already react on a short-term basis to hot days and spend more nights in hotels in mountain resorts. If heat waves become more regular, it seems likely that tourists will choose to stay at alpine resorts more frequently and for longer periods.” G. Serquet and M. Rebetez, Climatic Change, 2011, DOI: 10.1007/s10584-010-0012-6.

MWP not analogous to modern times advancing NA glaciers suggest

Extensive glaciers in northwest North America during Medieval time – Koch & Clague (2011) “The Medieval Warm Period is an interval of purportedly warm climate during the early part of the past millennium. The duration, areal extent, and even existence of the Medieval Warm Period have been debated; in some areas the climate of this interval appears to have been affected more by changes in precipitation than in temperature. Here, we provide new evidence showing that several glaciers in western North America advanced during Medieval time and that some glaciers achieved extents similar to those at the peak of the Little Ice Age, many hundred years later. The advances cannot be reconciled with a climate similar to that of the twentieth century, which has been argued to be an analog, and likely were the result of increased winter precipitation due to prolonged La Niña-like conditions that, in turn, may be linked to elevated solar activity. Changes in solar output may initiate a response in the tropical Pacific that directly impacts the El Niño/Southern Oscillation and associated North Pacific teleconnections.” Johannes Koch and John J. Clague, Climatic Change, 2011, DOI: 10.1007/s10584-010-0016-2.

Ocean blooms right after ice retreats

Near-ubiquity of ice-edge blooms in the Arctic – Perrette et al. (2011) “Ice-edge blooms are significant features of Arctic primary production, yet have received relatively little attention. Here we combine satellite ocean colour and sea-ice data in a pan-Arctic study. Ice-edge blooms occur in all seasonally ice-covered areas and from spring to late summer, being observed in 77–89% of locations for which adequate data exist, and usually peaking within 20 days of ice retreat. They sometimes form long belts along the ice-edge (greater than 100 km), although smaller structures were also found. The bloom peak is on average more than 1 mg m−3, with major blooms more than 10 mg m−3, and is usually located close to the ice-edge, though not always. Some propagate behind the receding ice-edge over hundreds of kilometres and over several months, while others remain stationary. The strong connection between ice retreat and productivity suggests that the ongoing changes in Arctic sea-ice may have a significant impact on higher trophic levels and local fish stocks.” Perrette, M., Yool, A., Quartly, G. D., and Popova, E. E., Biogeosciences, 8, 515-524, doi:10.5194/bg-8-515-2011, 2011. [full text]

Spanish hockey stick

Land surface temperature changes in Northern Iberia since 4000 yr BP, based on δ13C of speleothems – Martín-Chivelet et al. (2011) “The surface temperature changes for the last 4000 years in northern inland Iberia (an area particularly sensitive to climate change) are determined by a high resolution study of carbon stable isotope records of stalagmites from three caves (Kaite, Cueva del Cobre, and Cueva Mayor) separated several 10 s km away in N Spain. Despite the local conditions of each cave, the isotopic series show a good overall coherence, and resulted to be strongly sensitive to surface temperature changes. The record reflects alternating warmer and colder intervals, always within a temperature range of 1.6 °C. The timing and duration of the intervals were provided by 43 230Th–234U (ICP-MS) ages. Main climatic recognized periods are: (1) 3950–3000 yr BP: warm period punctuated by cool events around ~ 3950, 3550 and 3250 yr BP; (2) 2850–2500 yr BP cold interval (Iron Age Cold Period); (3) 2500–1650 yr BP moderate warm period (Roman Warm Period), with maximum temperatures between 2150 and 1750 yr BP; (4) 1650–1350 yr BP cold interval (Dark Ages Cold Period), with a thermal minimum at ~ 1500 yr BP; (5) 1350–750 yr BP warm period (Medieval Warm Period) punctuated by two cooler events at ~ 1250 and ~ 850 yr BP; (6) 750–100 yr BP cold period (Little Ice Age) with extremes occurring at 600–500 yr BP, 350–300 yr BP, and 150–100 yr BP; and (7) the last 150 years, characterized by rapid but no linear warming (Modern Warming). Remarkably, the presented records allow direct comparison of recent warming with former warm intervals such as the Roman or the Medieval periods. That comparison reveals the 20th Century as the time with highest surface temperatures of the last 4000 years for the studied area. Spectral analysis of the time series shows consistent climatic cycles of ~ 400, ~ 900 and ~ 1300 yr, comparable with those recognized in the North Atlantic marine record, the Greenland ice cores, and other terrestrial records for the middle – late Holocene, suggesting common climate forcing mechanisms related to changes in solar irradiance and North Atlantic circulation patterns.” Javier Martín-Chivelet, M. Belén Muñoz-García, R. Lawrence Edwards, María J. Turrero, and Ana I. Ortega, Global and Planetary Change, doi:10.1016/j.gloplacha.2011.02.002.

Elephant seals measuring the ocean

Delayed-mode calibration of hydrographic data obtained from animal-borne satellite-relay data loggers – Roquet et al. (2011) “A delayed-mode calibration procedure is presented to improve the quality of hydrographic data from CTD-Satellite-Relay Data Loggers (CTD-SRDL) deployed on elephant seals. This procedure is applied on a dataset obtained with 10 CTD-SRDLs deployed at Kerguelen Islands in 2007. A comparison of CTD-SRDLs with a ship-based CTD system is first presented. A pressure effect correction, linear with pressure, is deduced for both temperature and salinity measurements. An external field effect on conductivity sensor is also detected, inducing an additional salinity offset. The salinity offset cannot be estimated directly from the ship-based CTD comparisons, as the attachment of the CTD-SRDL on the seal head modifies the magnitude of the external field effect. Two methods are proposed to estimate a posteriori the salinity offset. The first method uses the stable salinity maximum characterizing the Lower Circumpolar Deep Water (LCDW), sampled by seals foraging south of the Southern Antarctic Circumpolar Current Front. Where this approach is not possible, a statistical method of cross-comparison of CTD-SRDLs surface salinity measurements is used over the sluggish Northern Kerguelen Plateau. Accuracies are respectively estimated as ± 0.02 °C for temperature and ± 0.1 for derived salinity without corrections. The delayed-mode calibration improves significantly the CTD-SRDL data, improving accuracies to ± 0.01 °C and ± 0.03 respectively. A better salinity accuracy of ± 0.02 is achieved when the LCDW method can be used. For CTD-SRDLs where ship-based CTD comparisons are not available, the expected accuracy would be ± 0.02 °C for temperature and ± 0.04 for the derived salinity.” Fabien Roquet, Jean-Benoit Charrassin, Stephane Marchand, Lars Boehme, Mike Fedak, Gilles Reverdin and Christophe Guinet, Journal of Atmospheric and Oceanic Technology 2011.

Younger Dryas event probably not caused by impact

The Younger Dryas impact hypothesis: A requiem – Pinter et al. (2011) “The Younger Dryas (YD) impact hypothesis is a recent theory that suggests that a cometary or meteoritic body or bodies hit and/or exploded over North America 12,900 years ago, causing the YD climate episode, extinction of Pleistocene megafauna, demise of the Clovis archaeological culture, and a range of other effects. Since gaining widespread attention in 2007, substantial research has focused on testing the 12 main signatures presented as evidence of a catastrophic extraterrestrial event 12,900 years ago. Here we present a review of the impact hypothesis, including its evolution and current variants, and of efforts to test and corroborate the hypothesis. The physical evidence interpreted as signatures of an impact event can be separated into two groups. The first group consists of evidence that has been largely rejected by the scientific community and is no longer in widespread discussion, including: particle tracks in archeological chert; magnetic nodules in Pleistocene bones; impact origin of the Carolina Bays; and elevated concentrations of radioactivity, iridium, and fullerenes enriched in 3He. The second group consists of evidence that has been active in recent research and discussions: carbon spheres and elongates, magnetic grains and magnetic spherules, byproducts of catastrophic wildfire, and nanodiamonds. Over time, however, these signatures have also seen contrary evidence rather than support. Recent studies have shown that carbon spheres and elongates do not appear to represent extraterrestrial carbon nor impact-induced megafires, but rather fungal sclerotia and arthropod fecal material that are a small but common component of many terrestrial deposits. Magnetic grains and spherules are heterogeneously distributed in sediments, but reported measurements of unique peaks in concentrations at the YD onset have yet to be reproduced. The magnetic grains are certainly just iron-rich detrital grains, whereas reported YD magnetic spherules are consistent with the diffuse, non-catastrophic input of micrometeorite ablation fallout, probably augmented by anthropogenic and other terrestrial spherular grains. Results here also show considerable subjectivity in the reported sampling methods that may explain the purported YD spherule concentration peaks. Fire is a pervasive earth-surface process, and reanalyses of the original YD sites and of coeval records show episodic fire on the landscape through the latest Pleistocene, with no unique fire event at the onset of the YD. Lastly, with YD impact proponents increasingly retreating to nanodiamonds (cubic, hexagonal [lonsdaleite], and the proposed n-diamond) as evidence of impact, those data have been called into question. The presence of lonsdaleite was reported as proof of impact-related shock processes, but the evidence presented was inconsistent with lonsdaleite and consistent instead with polycrystalline aggregates of graphene and graphane mixtures that are ubiquitous in carbon forms isolated from sediments ranging from modern to pre-YD age. Important questions remain regarding the origins and distribution of other diamond forms (e.g., cubic nanodiamonds). In summary, none of the original YD impact signatures have been subsequently corroborated by independent tests. Of the 12 original lines of evidence, seven have so far proven to be non-reproducible. The remaining signatures instead seem to represent either (1) non-catastrophic mechanisms, and/or (2) terrestrial rather than extraterrestrial or impact-related sources. In all of these cases, sparse but ubiquitous materials seem to have been misreported and misinterpreted as singular peaks at the onset of the YD. Throughout the arc of this hypothesis, recognized and expected impact markers were not found, leading to proposed YD impactors and impact processes that were novel, self-contradictory, rapidly changing, and sometimes defying the laws of physics. The YD impact hypothesis provides a cautionary tale for researchers, the scientific community, the press, and the broader public.” Nicholas Pinter, Andrew C. Scott, Tyrone L. Daulton, Andrew Podoll, Christian Koeberl, R. Scott Anderson, and Scott E. Ishman, Earth-Science Reviews, 2011, doi:10.1016/j.earscirev.2011.02.005.

Measuring pollution events in real time

Continuous isotopic composition measurements of tropospheric CO2 at Jungfraujoch (3580 m a.s.l.), Switzerland: real-time observation of regional pollution events – Tuzson et al. (2011) “A quantum cascade laser based absorption spectrometer (QCLAS) is applied for the first time to perform in situ, continuous and high precision isotope ratio measurements of CO2 in the free troposphere. Time series of the three main CO2 isotopologue mixing ratios (12C16CO2, 13C16CO2 and 12C18O16O) have simultaneously been measured at one second time resolution over two years (from August 2008 to present) at the High Altitude Research Station Jungfraujoch (3580 m a.s.l., Switzerland). This work focuses on periods in February 2009 only, when sudden and pronounced enhancements in the tropospheric CO2 were observed. These short-term changes were closely correlated with variations in CO mixing ratios measured at the same site, indicating combustion related emissions as potential source. The analytical precision of 0.046‰ (at 50 s integration time) for both δ13C and δ18O and the high temporal resolution allowed the application of the Keeling plot method for source signature identification. The spatial origin of these CO2 emission sources was then determined by backward Lagrangian particle dispersion simulations.” Tuzson, B., Henne, S., Brunner, D., Steinbacher, M., Mohn, J., Buchmann, B., and Emmenegger, L., Atmos. Chem. Phys., 11, 1685-1696, doi:10.5194/acp-11-1685-2011, 2011. [full text]

Convective activity might have enhanced in tropics

Three decades of intersatellite-calibrated High-Resolution Infrared Radiation Sounder upper tropospheric water vapor – Shi & Bates (2011) “To generate a climatologically homogenized time series of the upper tropospheric water vapor (UTWV), intersatellite calibration is carried out for 3 decades of High-Resolution Infrared Radiation Sounder (HIRS) channel 12 clear-sky measurements. Because of the independence of the individual satellite’s instrument calibration, intersatellite biases exist from satellite to satellite. To minimize the expected intersatellite biases, measurement adjustments are derived from overlapping HIRS data from the equator to the poles to account for the large global temperature observation range. Examination of the intersatellite biases shows that the biases are scene temperature–dependent. Many overlapping satellites have bias variations of more than 0.5 K across the scene temperature ranges. An algorithm is developed to account for the varying biases with respect to brightness temperature. Analyses based on the intercalibrated data show that selected regions of UTWV are highly correlated with low-frequency indexes such as the Pacific Decadal Oscillation index and the Pacific and North America index, especially in the winter months. The derived upper tropospheric humidity in the central Pacific also corresponds well with the Niño 3.4 index. Thirty year trend analysis indicates an increase of upper tropospheric humidity in the equatorial tropics. The areal coverage of both high and low humidity values also increased over time. These features suggest the possibility of enhanced convective activity in the tropics.” Shi, L., and J. J. Bates (2011), J. Geophys. Res., 116, D04108, doi:10.1029/2010JD014847.

Dominant role of GHG’s in past interglacials

Individual contribution of insolation and CO2 to the interglacial climates of the past 800,000 years – Yin & Berger (2011) “The individual contributions of insolation and greenhouse gases (GHG) to the interglacial climates of the past 800,000 years are quantified through simulations with a model of intermediate complexity LOVECLIM and using the factor separation technique. The interglacials are compared in terms of their forcings and responses of surface air temperature, vegetation and sea ice. The results show that the relative magnitude of the simulated interglacials is in reasonable agreement with proxy data. GHG plays a dominant role on the variations of the annual mean temperature of both the Globe and the southern high latitudes, whereas, insolation plays a dominant role on the variations of tree fraction, precipitation and of the northern high latitude temperature and sea ice. The Mid-Brunhes Event (MBE) appears to be significant only in GHG and climate variables dominated by it. The results also show that the relative importance of GHG and insolation on the warmth intensity varies from one interglacial to another. For the warmest (MIS-9 and MIS-5) and coolest (MIS-17 and MIS-13) interglacials, GHG and insolation reinforce each other. MIS-11 (MIS-15) is a warm (cool) interglacial due to its high (low) GHG concentration, its insolation contributing to a cooling (warming). MIS-7, although with high GHG concentrations, can not be classified as a warm interglacial due to it large insolation-induced cooling. Related to these two forcings, MIS-19 appears to be the best analogue for MIS-1. In the response to insolation, the annual mean temperatures averaged over the globe and over southern high latitudes are highly linearly correlated with obliquity. However, precession becomes important in the temperature of the northern high latitudes and controls the tree fraction globally. Over the polar oceans, the response during the local winters, although the available energy is small, is larger than during the local summers due to the summer remnant effect. The sensitivity to double CO2 is the highest for the coolest interglacial.” Qiu Zhen Yin and André Berger, Climate Dynamics, 2011, DOI: 10.1007/s00382-011-1013-5.

Review on tropical cyclones and climate change

Tropical cyclones, climate change, and scientific uncertainty: what do we know, what does it mean, and what should be done? – Grossmann & Morgan (2011) “The question of whether and to what extent global warming may be changing tropical cyclone (TC) activity is of great interest to decision makers. The presence of a possible climate change signal in TC activity is difficult to detect because interannual variability necessitates analysis over longer time periods than available data allow. Projections of future TC activity are hindered by computational limitations and uncertainties about changes in regional climate, large scale patterns, and TC response. This review discusses the state of the field in terms of theory, modeling studies and data. While Atlantic TCs have recently become more intense, evidence for changes in other basins is not persuasive, and changes in the Atlantic cannot be clearly attributed to either natural variability or climate change. However, whatever the actual role of climatic change, these concerns have opened a “policy window” that, if used appropriately, could lead to improved protection against TCs.” Iris Grossmann and M. Granger Morgan, Climatic Change, 2011, DOI: 10.1007/s10584-011-0020-1.


One Response to “New research from last week 8/2011”

  1. Ari Jokimäki said

    A comment has been made about Martin-Chivelet et al.:

    Comment on “Land surface temperature changes in Northern Iberia since 4000 yr BP, based on δ13C of speleothems” – Domínguez-Villar (2012)

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