A group of British oceanographers studied changes in seawater salinity in the North Atlantic and concluded that freshwater from melting Arctic ice would likely affect summer weather in Europe.

Extreme temperature jumps in Europe are explained by the strong melting of the Arctic ice and the Greenland ice sheet. Naked Science has already described how from 1980 to 2010 the island “greened” by 111% and the area of ​​wetlands increased almost fourfold. The Arctic region is warming at twice the global average; This is specifically expressed in the volume of freshwater entering the ocean. This effect is called Arctic amplification.

Various assumptions have previously been made that Arctic ice loss is statistically related to extreme weather conditions in the mid-latitudes. The researchers observed that winter cold anomalies in the subpolar region precede heat waves in Europe the following summer. However, the mechanisms of this effect are not fully understood.

British oceanographers decided to apply a new method to study ocean changes. The fact is that previous studies faced difficulties in modeling water salinity, and information received from satellites and buoys did not fully reflect the real picture. A new study was published in the journal Weather and Climate Dynamicsexplains how the contribution of meltwater could affect weather in Europe this summer.

The authors used data from 1979 to 2022 in their calculations. Using surface water mass balance analysis, they examined how freshwater spreads and affects ocean salinity. The researchers made summer weather forecasts for Europe based on statistical and correlational analysis of the ten hottest and ten coldest periods.

As the authors explain, during autumn and winter the air of the subpolar region is colder than the ocean surface—so the upper layer of water cools, condenses, and sinks. It is replaced by warmer water, which must be cooled again. However, during this heat exchange process, fresh water, which is not as dense as salt water, enters everywhere. As a result, heat exchange is disrupted and the atmosphere of the region becomes unstable.

Cyclone anomalies occur, the North Atlantic flow (a continuation of the Gulf Stream) is diverted to the north. As a result, oceanographers write, the air is warming in the south of the subpolar zone, winds are shifting to the north, and such effects of hurricanes lead to anticyclones over Europe. Namely, to the warmer and drier weather in the region.

“Based on the chain of events identified, we expect ocean atmospheric conditions to be suitable for an unusually hot and dry summer in Southern Europe this year,” said Marilena Oltmanns, author of the new study.

However, it is worth noting that the large number of factors that cause sea water exchange (precipitation, evaporation, river flow, mixing with currents and others) make an accurate assessment of its salinity almost impossible.

In general, regarding the year 2024 for part of Europe (for example, the East), the prediction of the authors of the new study may come true: experience shows that in years when winter in Russia is cold, for example, the next summer is determined to be relatively dry and warm, thanks to anticyclones. However, it is unclear whether such mechanisms will work in the long term.

The fact is that 120 thousand years ago the global temperature was one degree higher than today, that is, the climate was similar to what awaits us in the last quarter of the 21st century. At the same time, it was observed that trees such as hornbeam spread rapidly in Europe (up to Valdai). Hornbeams do not tolerate severe frosts or severe droughts. Meanwhile, summers with anticyclones can often lead to severe droughts. In other words, during the severe warming experienced 120 thousand years ago, extremely dry summer weather was clearly not observed in Europe.