Abstract: We present summer site testing results based on DIMM data obtained at Dome C, Antarctica. These data were collected on the bright star Canopus during two 3-months summer campaigns in 2003-2004 and 2004-2005. We performed continuous monitoring of the seeing and the isoplanatic angle in the visible. We found a median seeing of 0.54'' and a median isoplanatic angle of 6.8''. The seeing appears to have a deep minimum around 0.4'' almost every day in late afternoon.

Abstract: Theoretical studies have shown that variation in density regulation strongly influences population dynamics1, yet our understanding of factors influencing the strength of density dependence in natural populations still is limited2. Consequently, few general hypotheses have been advanced to explain the large differences between species in the magnitude of population fluctuations3, 4, 5, 6. One reason for this is that the detection of density regulation in population time series is complicated by time lags induced by the life history of species7, 8 that make it difficult to separate the relative contributions of intrinsic and extrinsic factors to the population dynamics. Here we use population time series for 23 bird species to estimate parameters of a stochastic density-dependent age-structured model. We show that both the strength of total density dependence in the life history and the magnitude of environmental stochasticity, including transient fluctuations in age structure, increase with generation time. These results indicate that the relationships between demographic and life-history traits in birds9, 10 translate into distinct population dynamical patterns that are apparent only on a scale of generations.

Abstract: Two deep ice cores from central Greenland, drilled in the 1990s, have played a key role in climate reconstructions of the Northern Hemisphere, but the oldest sections of the cores were disturbed in chronology owing to ice folding near the bedrock. Here we present an undisturbed climate record from a North Greenland ice core, which extends back to 123,000 years before the present, within the last interglacial period. The oxygen isotopes in the ice imply that climate was stable during the last interglacial period, with temperatures 5 °C warmer than today. We find unexpectedly large temperature differences between our new record from northern Greenland and the undisturbed sections of the cores from central Greenland, suggesting that the extent of ice in the Northern Hemisphere modulated the latitudinal temperature gradients in Greenland. This record shows a slow decline in temperatures that marked the initiation of the last glacial period. Our record reveals a hitherto unrecognized warm period initiated by an abrupt climate warming about 115,000 years ago, before glacial conditions were fully developed. This event does not appear to have an immediate Antarctic counterpart, suggesting that the climate see-saw between the hemispheres (which dominated the last glacial period) was not operating at this time.

Abstract: The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok. The earlier period, between 740,000 and 430,000 years ago, was characterized by less pronounced warmth in interglacial periods in Antarctica, but a higher proportion of each cycle was spent in the warm mode. The transition from glacial to interglacial conditions about 430,000 years ago (Termination V) resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases, but there are significant differences in the patterns of change. The interglacial stage following Termination V was exceptionally long—28,000 years compared to, for example, the 12,000 years recorded so far in the present interglacial period. Given the similarities between this earlier warm period and today, our results may imply that without human intervention, a climate similar to the present one would extend well into the future.
EPICA community members* (participants are listed alphabetically)
Laurent Augustin1, Carlo Barbante2, Piers R. F. Barnes3, Jean Marc Barnola1, Matthias Bigler4, Emiliano Castellano5, Olivier Cattani6,
Jerome Chappellaz1, Dorthe Dahl-Jensen7, Barbara Delmonte1,8, Gabrielle Dreyfus6, Gael Durand1, Sonia Falourd6, Hubertus Fischer9,
Jacqueline Fluckiger4, Margareta E. Hansson10, Philippe Huybrechts9, Gerard Jugie11, Sigfus J. Johnsen7, Jean Jouzel6, Patrik Kaufmann4,
Josef Kipfstuhl9, Fabrice Lambert4, Vladimir Y. Lipenkov12, Genevieve C. Littot3, Antonio Longinelli13, Reginald Lorrain14, Valter Maggi8,
Valerie Masson-Delmotte6, Heinz Miller9, Robert Mulvaney3, Johannes Oerlemans15, Hans Oerter9, Giuseppe Orombelli8, Frederic Parrenin1,6,
David A. Peel3, Jean-Robert Petit1, Dominique Raynaud1, Catherine Ritz1, Urs Ruth9, Jakob Schwander4, Urs Siegenthaler4, Roland Souchez14,
Bernhard Stauffer4, Jorgen Peder Steffensen7, Barbara Stenni16, Thomas F. Stocker4, Ignazio E. Tabacco17, Roberto Udisti5,
Roderik S. W. van de Wal15, Michiel van den Broeke15, Jerome Weiss1, Frank Wilhelms9, Jan-Gunnar Winther18, Eric W. Wolff3 & Mario Zucchelli19*
1, Laboratoire de Glaciologie et Geophysique de l’Environnement (CNRS), BP 96, 38402 St Martin d’Heres Cedex, France; 2, Environmental Sciences Department,
University of Venice, Calle Larga S. Marta, 2137, I-30123 Venice, Italy; 3, British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK; 4, Climate
and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland; 5, Department of Chemistry—Analytical Chemistry
Section, Scientific Pole—University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino (Florence), Italy; 6, Institut Pierre Simon Laplace/Laboratoire des Sciences
du Climat et de l’Environnement, UMR CEA-CNRS 1572, CE Saclay, Orme des Merisiers, 91191 Gif-Sur-Yvette, France; 7, Niels Bohr Institute for Astronomy, Physics
and Geophysics, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark; 8, University of Milano-Bicocca, Dipartimento di Scienze Ambiente
e Territorio, Piazza della Scienza 1, I-20126 Milan, Italy; 9, Alfred-Wegener-Institute for Polar- und Marine Research (AWI), Postfach 120161, D-27515 Bremerhaven,
Germany; 10, Department of Physical Geography and Quaternary Geology, Stockholm University, S-106 91 Stockholm, Sweden; 11, Institut Polaire Francais–Paul Emile Victor (IPEV), BP 75, 29280 Plouzane, France; 12, Arctic and Antarctic Research Institute, 38 Beringa Street, 199397 St Petersburg, Russia; 13, Department of Earth Sciences, University of Parma, Parco Area delle Scienze 157/A, I-43100 Parma, Italy; 14, Departement des Sciences de la Terre et de l’Environnement, Faculte des Sciences, CP 160/03, Universite Libre de Bruxelles, 50 avenue FD Roosevelt, B1050 Brussels, Belgium; 15, Institute for Marine and Atmospheric Research Utrecht
(IMAU), Princetonplein 5, 3584 CC Utrecht, The Netherlands; 16, Department of Geological, Environmental and Marine Sciences, University of Trieste, Via E. Weiss 2,
I-34127 Trieste, Italy; 17, Earth Science Department, University of Milan, Via Cicognara 7, 20129 Milano, Italy; 18, Norwegian Polar Institute, N-9296 Tromsø, Norway;
19, ENEA, CRE Casaccia, PO Box 2400, Via Anguillarese 301, 00060 S. Maria di Galleria (RM), Italy.
*Deceased.