Dimitri Defrance , Thibault Catry, Amélie Rajaud, Nadine Dessay, Benjamin Sultan

That is a preprint of an article suubmitted at Applied Greography (20tf of March 19). Climate change studies in the last decades have been based on Global Climate Models (GCM), and the distribution of climatic regions over time extracted from these models can be represented using the Köppen climatic classification. The Köppen approach predicts the distribution of biomes worldwide on the basis of monthly precipitation and average temperature. This study aims to use the Köppen classification to evaluate the impact of the Greenland and Antarctic ice sheets melting on GCM simulation results at the regional and global scale. To assess the impact of accelerated ice-sheet melting, our approach is based on numerical simulations from the IPSL-CM5A-LR GCM with the introduction of freshwater near the ice sheets superimposed on the RCP8.5 scenario, leading to a global warming of +5°C. Static mapping of distribution changes in Köppen climatic regions under various scenarios (historical run from observations, RCP 8.5, and various cases of polar sheets melting) and comparisons between them reveal that major changes occur at the global scale for the period 2041-2060. A first level of analysis revealed that, when the input of freshwater originates from Greenland or Antarctica, the inter-tropical belt undergoes greater change than under the RCP8.5 scenario. A second level of analysis showed that changes in precipitation have major impacts on the southern hemisphere, with more drastic changes if the freshwater came from the Greenland ice sheet than if it came from Antarctica or from the combination of both. Changes in temperature, however, strongly impact the northern hemisphere, and are significantly affected by the melting of the Greenland ice sheet. This study highlights the importance of considering ice sheets melting in the modelling of future global climate.