Decadal climate variability and potential predictability in the Nordic region: a review

This paper reviews decadal climate variability and predictability and its potential implications for adaptation decisions with emphasis on the Nordic region. In the North Atlantic sector, there is strong decadal to multi-decadal climate variability. The most prominent internal mechanisms explaining the variability are the North Atlantic oscillation (NAO) and the Atlantic meridional overturning circulation (AMOC). These affect also the climate variability in the Nordic region, but their impacts vary depending on local and regional conditions. The published studies also indicate that there appears to be potential for predictability of the decadal climate variations in the North Atlantic sector, mainly due to the AMOC variations. This also contributes to the predictability in the Nordic region, especially in the coastal areas adjacent to North Atlantic. The conclusions are uncertain at the moment, despite the fact that new knowledge is rapidly accumulating. Potential decadal predictability may generally be reduced due to global warming which is the largest over the high latitude oceans. For instance, weakening of the AMOC is generally noted in warmer world simulations. This may have consequences also on climate in the Nordic region, although the response is still uncertain.