How a warmer Arctic could lead to more extreme weather conditions

How a warmer Arctic could lead to more extreme weather conditions

Climatological experts are concerned that more and more extreme weather events are occurring in the northern hemisphere. Guilty party? A warmer Arctic, which could potentially disrupt the polar jet stream.

Whether sun or rain has lasted for days, the Northern Hemisphere experiences long periods of time, especially in the summer.

This leads to more extreme weather events, from and to

Climatologists explain that the increase in these prolonged extreme weather events is due to the persistence of fast air currents, in particular the polar jet stream, which has deviated from its usual patterns due to atmospheric pollution.

How does a warmer Arctic disrupt the jet stream?

Linking the higher temperatures around the North Pole with the extreme weather in parts of Europe, North America and Asia seems a little complicated, but it is essentially the atmosphere. Most weather events on our planet actually begin at a distance of 8 to 17 kilometers above the ground.

"Huge air flows gravitate around our Earth in the upper troposphere. We call them planetary waves, "said Joachim Schellnhuber of the Potsdam Institute for Climate Impact Research (PIK).

"It is becoming increasingly clear that humanity is essentially confusing these wind currents," he said. Fueled by human-induced greenhouse gas emissions, such natural circulation patterns are likely to be skewed by global warming, he said.

The air waves carrying chains of high and low pressure zones oscillate from west to east, between the equator and the North Pole.

A "curvier" polar jet allows the weather to last longer, resulting in more violent storms, longer droughts and stronger heat waves

But they can stay stuck and slow down, which blocks the time it does in a given region. It "turns precipitation into floods, sunny days into heat waves and dry conditions into forest fires," said Schellnhuber.

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Climatological researchers attribute the disruption of these wind currents, also known as jet currents, to changes in temperature in the region between the Arctic and the equator.

Due to global warming, the Arctic is warming faster than the rest of the northern hemisphere. This, in turn, reduces the difference in temperature between the North Pole and the Equator, which is the driving force behind jet currents.

"Many studies now suggest a more frequent blockage or increased blockage of latent airflow means," said Simon Wang of Utah State University.

There is evidence that winds associated with summer weather systems weaken and interact with these waves. "These combined effects suggest that weather conditions in the northern hemisphere last longer and therefore become extreme weather events."

Air pollution also slows the flow of air

According to climatologist estimates, disturbed jet streams contributed to the devastation, and.

"Such events occur more often than expected because of the direct effects of global warming, so there must be an additional effect of climate change occurring here," said climatologist Michael Mann of Pennsylvania State University.

Using computer simulations, he and another colleague have discovered another factor that can slow down and cause more jet currents in the world: air pollution composed of particles and sulfur particles. , as well as soot suspended in the air. liquid droplets or air in so-called anthropogenic aerosols.

The results of this research have now been published in the journal Science Advances.

Delhi in India is currently experiencing intense atmospheric pollution

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This is because air pollution blocks some of the solar radiation. In areas with many coal-fired plants, for example, regional temperatures are slightly colder – at least temporarily.

The same effect also reduces the temperature difference between mid-latitudes and the Arctic, making it another driving factor in the disruption of atmospheric airflow.

So, could this change be permanent? Stefan Rahmstorf of PIK, and one of the co-authors of the latest study, think that the balance can still be restored in the streams of jets.

"Our results also suggest that reducing air pollution in industrialized countries could actually restore some of the natural temperature difference between mid-latitudes and the Arctic," he said. declared.

Part of the Greenland Glacier retreats quickly due to warmer temperatures

More research needed

Until now, the study and computer simulations have received a positive response from other climatologists. "[We are now able to] diagnose extreme weather conditions by using simple analyzes, "said Johannes Quaas, professor of theoretical meteorology at the University of Leipzig.

Markus Rex, of the Alfred Wegener Institute for Polar and Marine Research, said the research demonstrated "the dire consequences of the dramatic warming of the Arctic for the extreme weather conditions in our latitudes, particularly the The incidence of prolonged heat waves in summer ".

Improving air quality is a new aspect of research, he added.

But Rex also stressed the need for further research on temperature changes in the Arctic to better understand the processes taking place in the Arctic climate system.

Summer of extremes

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Summer of extremes

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