Future Scenarios of Modes of Euro-Atlantic Atmospheric Variability: A First Look at CMIP6 Multi-Model Ensemble Results

Euro-Atlantic climate modes such as the North Atlantic Oscillation (NAO), the Eastern Atlantic pattern (EA), the Eastern Atlantic Western Russian pattern (EAWR) and the Scandinavian pattern (SCA) are known to significantly affect interannual-to-decadal climatic and hydroclimatic variability in the Euro-Mediterranean region. They are characterized by alternating positive and negative states of the associated index, each with specific climatic conditions that can last for several weeks or months and sometimes even years.

Knowing how these climate modes will be affected by future global warming conditions can help to constrain uncertainties in projections of Euro-Mediterranean regional climate variability.

In this contribution, we will present and discuss results from a CMIP6 multi-model analysis performed to investigate the presence of robust changes in these climate modes under the SSP585 future scenario of anthropogenic forcing  (fossil-fueled development with 8.5 W/m² forcing level). Toward this goal, we first search for a reliable box-based definition of an index for each of the abovementioned climate modes for the historical period and, then, perform a comparative assessment of the temporal, spectral and distributional properties of the so-defined indices during the historical (1850-2014) and future scenario (2014-2099) time periods, with a special focus on two interdecadal periods: 1960-1999 and 2060-2099. 

Early results show that there are significant changes in the future distributions of the climate modes with respect to the historical period, especially for what concerns the EA and the EAWR.