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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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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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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Monnin, E.; Indermuhle, A.; Dallenbach, A.; Fluckiger, J.; Stauffer, B.; Stocker, T.F.; Raynaud, D.; Barnola, J.-M. (2001). Atmospheric CO2 Concentrations over the Last Glacial Termination. Science, 291(5501), 112–114.
Abstract: A record of atmospheric carbon dioxide (CO2) concentration during the transition from the Last Glacial Maximum to the Holocene, obtained from the Dome Concordia, Antarctica, ice core, reveals that an increase of 76 parts per million by volume occurred over a period of 6000 years in four clearly distinguishable intervals. The close correlation between CO2 concentration and Antarctic temperature indicates that the Southern Ocean played an important role in causing the CO2 increase. However, the similarity of changes in CO2 concentration and variations of atmospheric methane concentration suggests that processes in the tropics and in the Northern Hemisphere, where the main sources for methane are located, also had substantial effects on atmospheric CO2 concentrations
Programme: 960
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Trampert, J.; Snieder, R. (1996). Model Estimations Biased by Truncated Expansions: Possible Artifacts in Seismic Tomography. Science, 271(5253), 1257–1260.
Abstract: In most linear imaging problems, where the model to be sought is expanded in a set of basis functions, it is common practice to truncate the set at a certain (arbitrary) level. The solution then depends on the chosen parameterization, and neglected basis functions may leak into the solution to produce artifacts in the retrieved model. An unbiased estimate of the coefficients of the true model may be obtained in the chosen finite basis set ; here, a method to suppress leakage is illustrated on an example of global seismic tomography.
Keywords: seismology ; tomography ; errors ; mathematical models ; methods ; inverse problem ; elastic waves ; Rayleigh waves ; algorithms
Programme: 133
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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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. (2019). Incidence of plastic ingestion in seabirds from the Bay of Biscay (southwestern Europe) (Vol. 146). Bachelor's thesis, , .
Abstract: Seabirds have been widely used to monitor marine debris by the analysis of plastic ingestion. With the aim of obtaining the first data on ingestion of plastics by different seabird species in the Bay of Biscay and evaluating their suitability as biomonitors of plastic pollution in this area, a total of 159 seabirds of fifteen species were analyzed. Plastics were found in 26 birds (16% of the individuals) of nine species (60% of the species). Frequency of occurrence of plastics varied between 0% (Razorbill) and 100% (species of the family Procellariidae). Considering several criteria to assess their suitability as biomonitors of plastic pollution (frequency of occurrence of plastic ingestion, species abundances and stranding occurrence in the Bay of Biscay), the Common Guillemot and the Atlantic Puffin seem the most promising candidates. This study provides the first data on plastic ingestion in seabirds of the Bay of Biscay.
Keywords: Plastic pollution; Plastic ingestion; Seabirds; Bay of Biscay; Marine Strategy Framework Directive
Programme: 388
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Traversi, R.; Becagli, S.; Castellano, E.; Cerri, O.; Morganti, A.; Severi, M.; Udisti, R. (2009). Study of Dome C site (East Antartica) variability by comparing chemical stratigraphies. Polar Chemistry, 92(1), 7–14.
Abstract: This paper compares chemical stratigraphies from snowpits collected at Dome C (East Antarctica) in order to assess site variability in terms of spatial distribution of chemical markers, annual accumulation rate and chemical species persistence in the snow layers. Since Dome C was chosen for deep drilling down to the bedrock in the framework of EPICA (European Project for Ice Coring in Antarctica), to provide 800kyr of climatic and environmental records, evaluating site variability is fundamental for a reliable interpretation of the deep ice core stratigraphies.
For this purpose, 4 snowpits were dug at Dome C (1997/98, 1998/99, 2000/01 and 2005/06 Antarctic Campaigns) and analysed for cations, inorganic anions and methane sulphonate by ion chromatography. Unlike the first three snowpits, the most recent one was analysed directly in situ, allowing to observe that no chemical contamination or loss due to sample storage and transport to Europe occurs for such a sampling.
Accumulation rate variability was revealed to be around 4% in a common time range (1992-1964) for all snowpits. Intra-snowpit chemical variability was definitely higher than inter-snowpit variability, indicating that the variations observed in the chemical stratigraphies from Dome C can be reliably related to effective changes in source and transport mechanisms of the investigated markers more than to site variability.
Post-depositional phenomena affecting chloride, nitrate and methane sulphonate were studied, revealing a logarithmic decay as a function of depth for Cl- and MSA and an exponential one for NO3-. The relative losses were quantified in the 75-80% range for Cl-, 66-83% for MSA and 89-94% for NO3- and were found to stop around 320, 320 and 60-80cm depth, respectively.
Keywords: Antarctica; Dome C; Snowpit; Chemical analysis; Post-depositional effects
Programme: 1181
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Loots Christophe, Swadling Kerrie M, Koubbi Philippe, . (2009). Journal of Marine Systems, 78(4), 599–605.
Keywords: Paralabidocera antarctica, Drescheriella glacialis, Stephos longipes, Southern Ocean, Sea ice, Life cycles,
Programme: 1142
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