Decadal predictability and variability of polar climate:
the role of atmosphere-ocean-cryosphere multiscale interactions


The climate of the polar regions has dramatically changed over the last decades. This may have resulted from external forcing (e.g., from greenhouse gas emissions), but also from natural interactions between the components of the climate system (notably, the atmosphere, the marine and continental cryosphere, and the ocean). Quantifying the specific contribution of each is critical to understand decadal climate variability, but it is also challenging. First, polar regions are notoriously under-sampled. Second, the dynamics of the high-latitude climate is characterized by strong couplings between the components of the climate system, which prevents any attempt to understand the system by studying its parts separately. Finally, a wide range of physical processes operate on a cascade of spatio-temporal scales (i.e., local effects have large-scale consequences).


Our first objective is to improve the understanding of key processes that control the variability of the ice-ocean- atmosphere system at decadal time scale. The focus will be on the interactions between the components at regional scale and on the links with larger spatial scales. A specific attention will be paid to the surface mass balance of ice sheets and ice shelves and their influence on both the ice sheet dynamics and the changes in the ocean and atmosphere.
A second objective is to determine how those interactions will lead to some predictability of the full ice-ocean- atmosphere system at decadal timescales or of some specific components only.


Achieving our goals will require the development of coupled regional models including the atmosphere, ocean, sea ice and ice sheets. Three configuration are proposed, covering 1/ Greenland, the Arctic and the North Atlantic sector, 2/ Antarctica and the Southern Ocean, 3/ The Totten glacier region. Retrospective (1980-2015) and prospective (2015-2045) climate simulations at high resolution will be conducted to evaluate the respective roles of initial conditions, some specific physical processes, teleconnections and couplings in the recent trends and to appreciate the potential fluctuations of key climate indicators within the next decades.