Presentation
The SAMIR project suggests to evaluate rapid climate variability (typically from annual to decadal scales) during the last thousand years in the centre of Antarctica using water isotopes in ice core records. To do so, we will combine a large number of ice cores, in-situ processes study as well as laboratory studies to understand the link between isotope and temperature, thanks to new instrumental developments.
ERC starting grant : 2024 – 2029
Coordinateur : M. Casado
The impact of climate change is the largest in polar regions, due to feedback loops leading to polar amplification. In Antarctica, short meteorological records hamper our ability to evaluate climate variability at interannual and decadal scales and discriminate anthropogenic forcings from natural variability. To obtain longer records, the isotopic composition of ice cores (δ18O, d-excess, and 17O-excess) provides continuous records retrievable across Antarctica. Yet, their interpretation is challenging due to multiple environmental contributions to the isotopic signal during archiving of snowfall into ice. Temperature reconstructions, obtained by a linear relationship between δ18O and temperature, mostly neglect these effects, limiting the power of reconstruction below multi-decadal resolution.
In the AVAR project, I will use time-scale dependent transfer functions between isotopic composition and temperature that take into account each process’s involvement during the climatic signal archiving in the ice cores and characterise their impact on the δ18O signal, and on d-excess and 17O-excess. Combining both mechanistic and statistical approaches will permit an improved study of the impact of climate change in Antarctica over the last 1000 years. This requires analysis of a large number of new ice cores in the Antarctic interior where few high-resolution records are currently available. Using new generation of infrared spectrometer (OFFS-CRDS), I will provide high precision and high pace isotopic composition measurements for precipitation, surface snow, atmospheric vapour, and interstitial vapour that were previously unfeasible in the extremely low Antarctic temperatures. Having overcome these technical hurdles, I will obtain the necessary data to constrain the transfer function between water isotopes and past climatic conditions as a function of the time scale, and solve the major obstruction of detecting the true impact of climate change in Antarctica.