2023 was a year of alarm for meteorologists. For the first time, the global average temperature rose in the short term to 1.5 degrees Celsius above pre-industrial levels. Alarming records have been set for rising sea levels, melting glaciers and extreme heat waves on land and oceans.

An intractable riddle

Much of this warming can be attributed to the high concentration of greenhouse gases in the atmosphere due to human impacts and the effects of the El Niño weather phenomenon. But even then, a gap of 0.2 degrees Celsius remained unexplained and puzzled scientists. And not at all optimistic predictions:

“This does not mean that the global average temperature will soon rise above eight degrees. But among the various climate models that exist, those that predict a significantly faster rise in temperature are likely to be correct. So we could already be closer to permanent global warming of more than 1.5 degrees Celsius than expected,” says Helge Gessling. He is a researcher at the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research.

The unrecognized clouds

In a recent study, which he authored, he seems to have found the culprit for this deterioration. They are called cumulus (cumulus, stratus or stratocumulus): They are the clouds that form at a fairly low altitude above the earth’s surface. Their common characteristic is that they reflect sunlight and thus cool its surface. And they are becoming fewer and fewer – at least in some areas. Exactly where record temperatures were recorded.

It was a long-held suspicion in scientific circles, as Gessling points out: “Such a link between global warming and clouds is suggested by several climate models. If it is indeed responsible for the phenomenon of reduced albedo, then we should expect a strong increase in temperature in the future.”

Another red flag

The so-called “planetary albedo” describes how much solar radiation is reflected back into space by the Earth’s surface and atmosphere. Low clouds “cool” the planet, while clouds in the higher layers have exactly the opposite effect. However, scientists still do not have a secure explanation for the reduction of the piles, which they attribute to human actions and interventions, which change the amount of suspended particles in the atmosphere. Certainly, however, they recorded their decrease based on the observed statistics from 1940 onwards.

What they confirmed in each case is that even faster and more decisive action against the climate crisis is urgently needed. “If we are to meet the 1.5 degree Celsius limit set in the Paris climate agreement, we must significantly reduce greenhouse gas emissions – and take urgent action to deal with the effects of extreme weather events expected in constantly,” Gesling warns.

Edited by: Kostas Argyros