Loss of Arctic sea ice could increase humidity in Spanish and Portuguese winters

Recent decades have shown a rapid decrease in ice concentration over the Arctic Ocean and climate projections suggest that this will continue in the future. There is now a good deal of scientific evidence about the potential role of Arctic ice loss on atmospheric circulation not only at high latitudes in the northern hemisphere, but also in other regions of the globe. This work uses a set of forced experiments with reductions in sea ice to quantify the possible effects on global atmospheric circulation, which represents an interesting methodology that also addresses a scientific issue of great relevance today.

The main results suggest that reductions in the amount of sea ice in the Arctic region promote the development of sea level pressure and geopotential anomalies through atmospheric teleconnections. These anomalies, through dynamical processes, would force noticeably drier conditions over the western United States and wetter conditions over Spain and Portugal during the winter quarter (December to February). It is interesting to note that some recent scientific work suggests similar changes in precipitation over the western United States. It is also relevant to mention that these results cannot be considered projections, since they only consider the effect of a reduction in the amount of Arctic sea ice without taking into account other relevant processes such as increases in greenhouse gas concentrations or even changes in soil type and management.

A potential limitation of the results lies in the number of climate models used: three. Such a number may be limited to adequately sample the uncertainty associated with these tools and, indeed, some patterns of variations (e.g. those shown in Figure 1 associated with variations in the sea level pressure field) are quite dissimilar between models.

In summary, this is very welcome work that contributes to the understanding of the possible effects of sea ice reduction on atmospheric circulation and derived variables such as precipitation.