AGW Observer

Observations of anthropogenic global warming

New research from last week 47/2010

Posted by Ari Jokimäki on November 29, 2010

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:

CO2 uptake not the only thing causing ocean acidification

Seasonal and long-term changes in pH in the Dutch coastal zone – Provoost et al. (2010) “Recent observations and modelling studies suggest that biogeochemical changes can mask atmospheric CO2-induced pH decreases. Data collected by the Dutch monitoring authorities in different coastal systems (North Sea, Wadden Sea, Ems-Dollard, Eastern Scheldt and Scheldt estuary) since 1975 provide an excellent opportunity to test whether this is the case in the Dutch coastal zone. The time-series were analysed using Multi-Resolution Analysis (MRA) which resulted in the identification of system-dependent patterns on both seasonal and intra-annual time scales. The observed rates of pH change greatly exceed those expected from enhanced CO2 uptake, thus suggesting that other biogeochemical processes, possibly related to changes in nutrient loading, can play a dominant role in ocean acidification.” Provoost, P., van Heuven, S., Soetaert, K., Laane, R. W. P. M., and Middelburg, J. J.: Seasonal and long-term changes in pH in the Dutch coastal zone, Biogeosciences, 7, 3869-3878, doi:10.5194/bg-7-3869-2010, 2010. [full text]

Calcifying invertebrates survive in CO2-rich environment but might not in future

Calcifying invertebrates succeed in a naturally CO2-rich coastal habitat but are threatened by high levels of future acidification – Thomsen et al. (2010) “CO2 emissions are leading to an acidification of the oceans. Predicting marine community vulnerability towards acidification is difficult, as adaptation processes cannot be accounted for in most experimental studies. Naturally CO2 enriched sites thus can serve as valuable proxies for future changes in community structure. Here we describe a natural analogue site in the Western Baltic Sea. Seawater pCO2 in Kiel Fjord is elevated for large parts of the year due to upwelling of CO2 rich waters. Peak pCO2 values of >230 Pa (>2300 μatm) and pHNBS values of <7.5 are encountered during summer and autumn, average pCO2 values are ~70 Pa (~700 μatm). In contrast to previously described naturally CO2 enriched sites that have suggested a progressive displacement of calcifying auto- and heterotrophic species, the macrobenthic community in Kiel Fjord is dominated by calcifying invertebrates. We show that blue mussels from Kiel Fjord can maintain control rates of somatic and shell growth at a pCO2 of 142 Pa (1400 μatm, pHNBS = 7.7). Juvenile mussel recruitment peaks during the summer months, when high water pCO2 values of ~100 Pa (~1000 μatm) prevail. Our findings indicate that calcifying keystone species may be able to cope with surface ocean pHNBS values projected for the end of this century when food supply is sufficient. However, owing to non-linear synergistic effects of future acidification and upwelling of corrosive water, peak seawater pCO2 in Kiel Fjord and many other productive estuarine habitats could increase to values >400 Pa (>4000 μatm). These changes will most likely affect calcification and recruitment, and increase external shell dissolution.” Thomsen, J., Gutowska, M. A., Saphörster, J., Heinemann, A., Trübenbach, K., Fietzke, J., Hiebenthal, C., Eisenhauer, A., Körtzinger, A., Wahl, M., and Melzner, F.: Calcifying invertebrates succeed in a naturally CO2-rich coastal habitat but are threatened by high levels of future acidification, Biogeosciences, 7, 3879-3891, doi:10.5194/bg-7-3879-2010, 2010. [full text]

Study compares concepts of slave ownership and fossil fuel usage

Past connections and present similarities in slave ownership and fossil fuel usage – Mouhot (2010) “The first part of the paper demonstrates the connection between the abolition of slavery and the Industrial Revolution: steam power changed the perception of labour; new techniques facilitated diffusion of pro-abolition pamphlets; fewer threats to basic existence resulting from industrial advances fostered sensibilities and moral standards toward abolitionism; and, through industrial development, the North grasped victory in the American Civil War. The second part presents similarities between societies in the past that have used slave labour and those in the present that use fossil fuels. It argues that slaves and fossil-fuelled machines play(ed) similar economic and social roles: both slave societies and developed countries externalise(d) labour and both slaves and modern machines free(d) their owners from daily chores. Consequently, we are as dependent on fossil fuels as slave societies were dependent on bonded labour. It also suggests that, in differing ways, suffering resulting (directly) from slavery and (indirectly) from the excessive burning of fossil fuels are now morally comparable. When we emit carbon dioxide at a rate that exceeds what the ecosystem can absorb, when we deplete non-renewable resources, we indirectly cause suffering to other human beings. Similarly, cheap oil facilitates imports of goods from countries with little social protection and hence help externalise oppression. The conclusion draws on the lessons which may be learned by Climate Change campaigners from the campaigns to abolish slavery: environmental apathy can be opposed effectively if we learn from what worked in the fight against this inhuman institution.” Jean-François Mouhot, Climatic Change, DOI: 10.1007/s10584-010-9982-7.

Cosmic rays linked to rapid mid-latitude cloud changes

Cosmic rays linked to rapid mid-latitude cloud changes – Laken et al. (2010) “The effect of the Galactic Cosmic Ray (GCR) flux on Earth’s climate is highly uncertain. Using a novel sampling approach based around observing periods of significant cloud changes, a statistically robust relationship is identified between short-term GCR flux changes and the most rapid mid-latitude (60°–30° N/S) cloud decreases operating over daily timescales; this signal is verified in surface level air temperature (SLAT) reanalysis data. A General Circulation Model (GCM) experiment is used to test the causal relationship of the observed cloud changes to the detected SLAT anomalies. Results indicate that the anomalous cloud changes were responsible for producing the observed SLAT changes, implying that if there is a causal relationship between significant decreases in the rate of GCR flux (~0.79 GU, where GU denotes a change of 1% of the 11-year solar cycle amplitude in four days) and decreases in cloud cover (~1.9 CU, where CU denotes a change of 1% cloud cover in four days), an increase in SLAT (~0.05 KU, where KU denotes a temperature change of 1 K in four days) can be expected. The influence of GCRs is clearly distinguishable from changes in solar irradiance and the interplanetary magnetic field. However, the results of the GCM experiment are found to be somewhat limited by the ability of the model to successfully reproduce observed cloud cover. These results provide perhaps the most compelling evidence presented thus far of a GCR-climate relationship. From this analysis we conclude that a GCR-climate relationship is governed by both short-term GCR changes and internal atmospheric precursor conditions.” Laken, B. A., Kniveton, D. R., and Frogley, M. R.: Cosmic rays linked to rapid mid-latitude cloud changes, Atmos. Chem. Phys., 10, 10941-10948, doi:10.5194/acp-10-10941-2010, 2010. [full text]

Testing for the seasonality of sea surface temperature proxies

Disentangling seasonal signals in Holocene climate trends by satellite-model-proxy integration – Schneider et al. (2010) “Past sea surface temperatures (SSTs) are routinely estimated from organic and inorganic remains of fossil phytoplankton or zooplankton organisms, recovered from seafloor sediments. Potential seasonal biases of paleoproxies were intensely studied in the past; however, even for the two most commonly used paleoproxies for SST, U37K′ and Mg/Ca ratios, a clear global picture does not yet exist. In the present study we combine Holocene SST trends derived from U37K′ and Mg/Ca ratios with results from idealized climate model simulations forced by changes in the orbital configuration, which represents the major climate driver over the last 10 kyr. Such changes cause a spatiotemporal redistribution of incoming solar radiation, resulting in a modulation of amplitude and phasing of the seasonal cycle. Considering that the climate signal recorded by a plankton-based paleoproxy may be affected by the seasonal productivity cycle of the respective organism, we use the modern relationship between SST and marine net primary production, both obtained from satellite observations, to calculate a seasonality index (SI) as an independent constraint to link modeled SST trends with proxy data. Although the climate model systematically underestimates Holocene SST trends, we find that seasonal productivity peaks of the phytoplankton-based U37K′ result in a preferential registering of the warm (cold) season in high (low) latitudes, as it was expected from the SI distribution. The overall smoother trends from the zooplankton-derived Mg/Ca SSTs suggest a more integrated signal over longer time averages, which may also carry a seasonal bias, but the spatial pattern is less clear. Based on our findings, careful multiproxy approaches can actually go beyond the reconstruction of average climate trends, specifically allowing to resolve the evolution of seasonality.” Schneider, B., G. Leduc, and W. Park (2010), Paleoceanography, 25, PA4217, doi:10.1029/2009PA001893. [full text]

Lakes have warmed rapidly since 1985

Space observations of inland water bodies show rapid surface warming since 1985 – Schneider & Hook (2010) “Surface temperatures were extracted from nighttime thermal infrared imagery of 167 large inland water bodies distributed worldwide beginning in 1985 for the months July through September and January through March. Results indicate that the mean nighttime surface water temperature has been rapidly warming for the period 1985–2009 with an average rate of 0.045 ± 0.011°C yr−1 and rates as high as 0.10 ± 0.01°C yr−1. Worldwide the data show far greater warming in the mid- and high latitudes of the northern hemisphere than in low latitudes and the southern hemisphere. The analysis provides a new independent data source for assessing the impact of climate change throughout the world and indicates that water bodies in some regions warm faster than regional air temperature. The data have not been homogenized into a single unified inland water surface temperature dataset, instead the data from each satellite instrument have been treated separately and cross compared. Future work will focus on developing a single unified dataset which may improve uncertainties from any inter-satellite biases.” Schneider, P., and S. J. Hook (2010), Geophys. Res. Lett., 37, L22405, doi:10.1029/2010GL045059.


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