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. (2009). Ecological Dynamics Across the Arctic Associated with Recent Climate Change (Vol. 325).
Abstract: At the close of the Fourth International Polar Year, we take stock of the ecological consequences of recent climate change in the Arctic, focusing on effects at population, community, and ecosystem scales. Despite the buffering effect of landscape heterogeneity, Arctic ecosystems and the trophic relationships that structure them have been severely perturbed. These rapid changes may be a bellwether of changes to come at lower latitudes and have the potential to affect ecosystem services related to natural resources, food production, climate regulation, and cultural integrity. We highlight areas of ecological research that deserve priority as the Arctic continues to warm.
Programme: 1036
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Morin, S.; Savarino, J.; Frey, M.M.; Yan, N.; Bekki, S.; Bottenheim, J.W.; Martins, J.M.F. (2008). Tracing the Origin and Fate of NOx in the Arctic Atmosphere Using Stable Isotopes in Nitrate. Science, 322(5902), 730–732.
Abstract: Atmospheric nitrogen oxides (NOx =NO+ NO2) play a pivotal role in the cycling of reactive nitrogen (ultimately deposited as nitrate) and the oxidative capacity of the atmosphere. Combined measurements of nitrogen and oxygen stable isotope ratios of nitrate collected in the Arctic atmosphere were used to infer the origin and fate of NOx and nitrate on a seasonal basis. In spring, photochemically driven emissions of reactive nitrogen from the snowpack into the atmosphere make local oxidation of NOx by bromine oxide the major contributor to the nitrate budget. The comprehensive isotopic composition of nitrate provides strong constraints on the relative importance of the key atmospheric oxidants in the present atmosphere, with the potential for extension into the past using ice cores.
Programme: 1011
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Gerday C., Aittaleb M., Arpigny J.L., Baise E., Chessa J.P., Francois J.M., Garsoux G., Petrescu I. & Feller G. (1997). Chimie nouvelle, 15(59), 1811–1817.
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Steffensen, J.P.; Andersen, K.K.; Bigler, M.; Clausen, H.B.; Dahl-Jensen, D.; Fischer, H.; Goto-Azuma, K.; Hansson, M.; Johnsen, S.J.; Jouzel, J.; Masson-Delmotte, V.; Popp, T.; Rasmussen, S.O.; Rothlisberger, R.; Ruth, U.; Stauffer, B.; Siggaard-Andersen, M.-L.; Sveinbjornsdottir, A.E.; Svensson, A.; White, J.W.C. (2008). High-Resolution Greenland Ice Core Data Show Abrupt Climate Change Happens in Few Years. Science, 321(5889), 680–684.
Abstract: The last two abrupt warmings at the onset of our present warm interglacial period, interrupted by the Younger Dryas cooling event, were investigated at high temporal resolution from the North Greenland Ice Core Project ice core. The deuterium excess, a proxy of Greenland precipitation moisture source, switched mode within 1 to 3 years over these transitions and initiated a more gradual change (over 50 years) of the Greenland air temperature, as recorded by stable water isotopes. The onsets of both abrupt Greenland warmings were slightly preceded by decreasing Greenland dust deposition, reflecting the wetting of Asian deserts. A northern shift of the Intertropical Convergence Zone could be the trigger of these abrupt shifts of Northern Hemisphere atmospheric circulation, resulting in changes of 2 to 4 kelvin in Greenland moisture source temperature from one year to the next.
Programme: 458
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Stephens, B.B.; Gurney, K.R.; Tans, P.P.; Sweeney, C.; Peters, W.; Bruhwiler, L.; Ciais, P.; Ramonet, M.; Bousquet, P.; Nakazawa, T.; Aoki, S.; Machida, T.; Inoue, G.; Vinnichenko, N.; Lloyd, J.; Jordan, A.; Heimann, M.; Shibistova, O.; Langenfelds, R.L.; Steele, L.P.; Francey, R.J.; Denning, A.S. (2007). Weak Northern and Strong Tropical Land Carbon Uptake from Vertical Profiles of Atmospheric CO2. Science, 316(5832), 1732–1735.
Abstract: Measurements of midday vertical atmospheric CO2 distributions reveal annual-mean vertical CO2 gradients that are inconsistent with atmospheric models that estimate a large transfer of terrestrial carbon from tropical to northern latitudes. The three models that most closely reproduce the observed annual-mean vertical CO2 gradients estimate weaker northern uptake of -1.5 petagrams of carbon per year (Pg C year-1) and weaker tropical emission of +0.1 Pg C year-1 compared with previous consensus estimates of -2.4 and +1.8 Pg C year-1, respectively. This suggests that northern terrestrial uptake of industrial CO2 emissions plays a smaller role than previously thought and that, after subtracting land-use emissions, tropical ecosystems may currently be strong sinks for CO2.
Programme: 416
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Le Quere, C.; Rodenbeck, C.; Buitenhuis, E.T.; Conway, T.J.; Langenfelds, R.; Gomez, A.; Labuschagne, C.; Ramonet, M.; Nakazawa, T.; Metzl, N.; Gillett, N.; Heimann, M. (2007). Saturation of the Southern Ocean CO2 Sink Due to Recent Climate Change. Bachelor's thesis, , .
Abstract: Based on observed atmospheric CO2 concentration and an inverse method, we estimate that the Southern Ocean sink of CO2 has weakened between 1981 and 2004 by 0.08 PgC/y per decade relative to the trend expected from the large increase in atmospheric CO2. This weakening is attributed to the observed increase in Southern Ocean winds resulting from human activities and projected to continue in the future. Consequences include a reduction in the efficiency of the Southern Ocean sink of CO2 in the short term (~25 years) and possibly a higher level of stabilization of atmospheric CO2 on a multicentury time scale.
Programme: 416;439
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Baroni, M.; Thiemens, M.H.; Delmas, R.J.; Savarino, J. (2007). Mass-Independent Sulfur Isotopic Compositions in Stratospheric Volcanic Eruptions. Science, 315(5808), 84–87.
Abstract: The observed mass-independent sulfur isotopic composition ({Delta}33S) of volcanic sulfate from the Agung (March 1963) and Pinatubo (June 1991) eruptions recorded in the Antarctic snow provides a mechanism for documenting stratospheric events. The sign of {Delta}33S changes over time from an initial positive component to a negative value. {Delta}33S is created during photochemical oxidation of sulfur dioxide to sulfuric acid on a monthly time scale, which indicates a fast process. The reproducibility of the results reveals that {Delta}33S is a reliable tracer to chemically identify atmospheric processes involved during stratospheric volcanism.
Programme: 457;1011
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BellotHerve, TrouvilliezAlexandre, Naaim-BouvetFlorence, GenthonChristophe, GalleeHubert, . (2011). Present weather-sensor tests for measuring drifting snow
. ANNALS OF GLACIOLOGY, 52(58), 176–184.
Abstract: In Antarctica, blowing snow accounts for a major component of the surface mass balance near the coast. Measurements of precipitation and blowing snow are scarce, and therefore collected data would allow testing of numerical models of mass flux over this region. A present weather station (PWS), Biral VPF730, was set up on the coast at Cap Prud'homme station, 5 km from Dumont d'Urville (DDU), principally to quantify precipitation. Since we expected to be able to determine blowing-snow fluxes from the PWS data, we tested this device first on our experimental site, the Lac Blanc pass. An empirical calibration was made with a snow particle counter. Although the physics of the phenomenon was not well captured, the flux outputs were better than those from FlowCapts. The first data from Antarctica were reanalyzed. The new calibration seems to be accurate for estimating the high blowing-snow flux with an interrogation of the precipitation effects.
Programme: 1013
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. (2011). Present weather-sensor tests for measuring drifting snow
. 0260-3055, 52(58), 176–184.
Abstract: In Antarctica, blowing snow accounts for a major component of the surface mass balance near the coast. Measurements of precipitation and blowing snow are scarce, and therefore collected data would allow testing of numerical models of mass flux over this region. A present weather station (PWS), Biral VPF730, was set up on the coast at Cap Prud'homme station, 5 km from Dumont d'Urville (DDU), principally to quantify precipitation. Since we expected to be able to determine blowing-snow fluxes from the PWS data, we tested this device first on our experimental site, the Lac Blanc pass. An empirical calibration was made with a snow particle counter. Although the physics of the phenomenon was not well captured, the flux outputs were better than those from FlowCapts. The first data from Antarctica were reanalyzed. The new calibration seems to be accurate for estimating the high blowingsnow flux with an interrogation of the precipitation effects.
Programme: 411
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Masson-Delmotte, V.; Jouzel, J.; Landais, A.; Stievenard, M.; Johnsen, S.J.; White, J.W.C.; Werner, M.; Sveinbjornsdottir, A.; Fuhrer, K. (2005). GRIP Deuterium Excess Reveals Rapid and Orbital-Scale Changes in Greenland Moisture Origin. Science, 309(5731), 118–121.
Abstract: The Northern Hemisphere hydrological cycle is a key factor coupling ice sheets, ocean circulation, and polar amplification of climate change. Here we present a Northern Hemisphere deuterium excess profile covering one climatic cycle, constructed with the use of {delta}18O and {delta}D Greenland Ice Core Project (GRIP) records. Past changes in Greenland source and site temperatures are quantified with precipitation seasonality taken into account. The imprint of obliquity is evidenced in the site-to-source temperature gradient at orbital scale. At the millennial time scale, GRIP source temperature changes reflect southward shifts of the geographical locations of moisture sources during cold events, and these rapid shifts are associated with large-scale changes in atmospheric circulation.
Programme: 458
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