Conférence du cycle de conférences du Géotop, mercredi 10 octobre 11h au PK-1140
Anais Orsi du Laboratoire des Sciences du Climat et de l’Environnement, CEA Saclay, Gif-sur-Yvette, présentera l'état des connaissances sur le climat antarctique des deux derniers millénaires.
Résumé:
The Antarctic continent is one of the most remote place on Earth, and yet, it is a key. With the recent climate change, we expect the polar regions to warm more than the rest of the planet in the coming decades. Yet, even in the satellite era (since 1979), we are unable to say whether many parts of Antarctica have been warming or cooling. This is due in part of the very large interannual climate variability, which masks small trends, and in part due to the very limited network of in-situ observations. Temperature proxies from ice cores are a key to improve our knowledge of climate variability in Antarctica, not only for the distant past, but also for the last 50 years.
Here, we will review the current knowledge of the Antarctic temperature climatology and trends, from in-situ observations and satellite data. To go beyond the instrumental period, we will review existing temperature proxies, and explore which ones are suitable to answer those questions. In particular, we will present a compilation of 2000-years water isotope records over all of Antarctica (as part of the Pages-2K initiative), and provide 7 regional climate reconstructions around the continent. We will discuss the features of centennial to decadal scale climate variability in the continent, and put the recent period in the context of the past 2000 years. Finally, we will present a new temperature proxy, based on the analysis of inert gas isotopes (N2 and Ar), and explore the potential for more quantitative temperature reconstructions from Antarctic ice cores in the future.