After analyzing a set of high-resolution satellite data, researchers have highlighted an unexpected drying up of Arctic lakes since the beginning of the 2000s. The results have been published in the journal Nature Climate Change on August 29.
In a recent article, we mentioned the particularly rapid warming of the Arctic with a rate of rise in temperature almost four times higher than that of the world average. This dazzling evolution of the polar climate has multiple consequences, some of which are only beginning to be identified by scientists. This is the case, for example, for the lakes that surround the Arctic basin, from Alaska to Siberia, via Canada and northern Europe.
An unexpected drying up of lakes in the Arctic
Over the past twenty years, these bodies of water, which are precious for local biodiversity and indigenous peoples, have dried up or even disappeared. This phenomenon is all the more surprising since scientists were rather expecting a growth of high latitude lakes in the context of global warming. And for good reason, we thought that the thawing of the permafrost would promote their filling. However, it is precisely the opposite that is happening.
The study shows that if the process supposed to increase the filling of the lakes is indeed present, it is more than compensated by a drainage mechanism. Thus, by increasing drainage and soil erosion, the thawing of permafrost ultimately contributes to reducing the lake surface area, which is expressed in some cases by the total disappearance of water bodies. Another astonishing fact: in addition to global warming, the increase in precipitation also drives this development.
” It may seem counterintuitive that increased precipitation reduces surface water “Reports Jeremy Lichstein, co-author of the study. ” However, it turns out that the physical explanation was already in the scientific literature. Rainwater carries heat through the ground and accelerates permafrost thaw, which can open underground channels that drain the surface “. In other words, the models used so far have clearly underestimated this process.
A sign of a rapid thaw, the impact of which remains to be determined
Given the astronomical amounts of carbon stored in frozen Arctic soils, the question arises whether this discovery implies a faster-than-expected permafrost thaw and therefore a higher risk of carbon dioxide releases or of methane to the atmosphere. ” Our results suggest that permafrost thaw is happening even faster than we collectively anticipated “, says Elizabeth E. Webb, lead author of the study.
As to whether the emptying and drying up of lakes can further amplify the rate of permafrost thaw or, on the contrary, temper it, scientists remain cautious. ” It’s unclear exactly what the ins and outs are, but we do know that expanding lakes cause carbon losses orders of magnitude higher than in surrounding regions. “, reports the researcher.
Anyway, to hope to slow this threatening evolution, there is only one solution: to reduce greenhouse gas emissions as quickly as possible, a trajectory that the world still does not seem to have taken. .