Arctic warms four times faster than the rest of the Earth

Researchers have known for some time that, as an effect of the climate crisis, the Arctic has been warming faster than the rest of the planet. Definitions of how much faster, however, have varied. New research points out that the situation is more pronounced than imagined. According to the study, in the last 43 years, the region has been heating up four times faster than the planetary average.

This phenomenon is called polar amplification or Arctic amplification. Several possible explanations are associated with it, but one of the main ones is the loss of sea ice.

Until now, there were indications that the Arctic could be warming about two or even three times faster than the rest of the planet, a vastly underestimated estimate, according to the scientists who published the new research on Thursday. , in Communications Earth & Environment magazine.

The reality observed by the researchers is an average warming in the region up to four times faster. With the exception of a northern tip of the Atlantic Ocean, no region of the Arctic has warmed less than twice that of the rest of the globe.

At the other extreme, there are temperatures with a much more pronounced rate of increase. This is the case of the Nova Zembla archipelago region, with heating up to seven times faster than the terrestrial average. According to scientists, this more intense increase in the area can be explained mainly by the marked loss of surface ice in the Barents Sea. But changes in atmospheric circulation also push up the thermometers in this area.

To reach these conclusions, the researchers used several databases of Arctic temperatures from 1979 to 2021.

Despite accessing already available data, the scientists arrived at different rates, considerably higher than what we had previously.

This occurs, first of all, as they explain, due to the period of time chosen for this work. The date of 1979 is not random, the authors point out: from that year onwards, Arctic ice began to be continuously monitored by satellites, which makes the information more accurate and reliable (that is, the margins of error are minimized). In addition, this is a period when the Arctic began to warm up sharply.

Another explanation for this difference could simply be the fact that previous estimates were out of date. The Arctic continued to warm to the point of making the data observed in previous articles out of date.

Finally, one more possible explanation concerns what the Arctic is. Yes, it can be defined in different ways and thus encompass different areas, which logically leads to different results.

Another relevant point brought by the new research concerns the models used to understand how human activities impact the climate. In short, scientists throw into a simulation everything that humanity knows about the physical processes that affect the climate and, thus, it is possible to see where we started from and where we are going. The IPCC (UN Intergovernmental Panel on Climate Change) reports, for example, largely depend on these models.

According to the researchers, the latest models still underestimate the strength of polar amplification.

The research also shows that polar amplification is strongest in November, that is, in the late autumn of the Northern Hemisphere, and weakest in July, which coincides with previous research.

“The chance of a fourfold increase in Arctic warming in CMIP6 climate models [os mais recentes] are very small, indicating that the polar amplification seen in 1979–2021 is extremely unlikely or that climate models systematically tend to underestimate the phenomenon,” the study authors say.

“The physical mechanisms that lead climate models to underestimate polar amplification remain unknown,” they further write.

Thus, taking into account that climate models do not seem to be able to simulate the real polar amplification (at least in the period observed in the study), the projections that we currently make for the climate may end up being impacted, the researchers conclude.

_{The Planeta em Transe project is supported by the Open Society Foundations.}