Heat waves are nothing new
Summer heat waves have been around for years, but the extreme heat events of recent years are occurring more frequently and much more intensively than before. The Potsdam Institute for Climate Impact Research, for example, predicts that even more extreme heat waves can be expected in the coming years. It said the study clearly shows that double jet streams and their residence time are linked to heat extremes.
A jet stream is a fast-moving band of wind that flows from west to east at an altitude of about 10 kilometers. In what is known as a double jet condition, the jet stream splits into two branches of increased wind. Although the number of these jet streams moving over southern and northern Eurasia has not changed significantly, the length of these events has. This lengthening, combined with the man-made increase in temperature, will lead to more intense heat waves in the long term.
Europe is getting hotter
In Europe as a whole, 30 percent of the heat wave trends can be explained by the jet stream. Western Europe in particular is in the spotlight here, as 100 percent of the last heat waves can be attributed to jet streams. This is mainly due to the fact that heat waves can normally move across the Atlantic and be cooled down by this. In the case of the double jet condition, however, this is no longer possible, since the streams here approach from both the south and the north.
Variety of triggering factors
Double jets can be triggered by a variety of reasons besides chaotic atmospheric fluctuations. The persistence and the accompanying prolonged residence time can be explained, among other things, by the increased warming of the high latitudes, i.e. in land regions such as Siberia and Alaska. These warm too quickly in summer, resulting in a rapid decline in snow cover. The rapidly increasing temperature difference between ocean and land favors the prolonged existence of double jet conditions in summer.
Future research aims to shed more light on this trend, as climate models tend to underestimate extreme weather risks. Stopping the future amplification of heat trends due to double-jet states can be addressed by, among other things, changing your own behavior and changing it. Calculate your CO₂ footprint now and offset right here.
Source:
https://www.nature.com/articles/s41467-022-31432-y