This severe weather episode also caused record damage estimated at $200 million.
While it has now been proven that global warming causes massive heat waves, the question of its effect on such cold waves remains the subject of intense scientific debate.
For the first time, a large study was published Thursday in the journal Science He succeeded in showing the link between changes brought about by global warming in the Arctic and bouts of winter cold in the northern hemisphere, in the United States, but also in Asia.
It seems illogical and unexpected that this apparent warming of the Arctic is causing cooling in other regions.Matthew Barlow, one of the study’s authors, admits to AFP.
However, despite this discrepancy, the researchers are conclusive.
I was a little surprised that the results were so clear, that we were able to make such direct contact, professor of climate sciences at the University of Massachusetts Lowell.
Two appearances at work
The North Pole is the fastest warming region on the planet.
But two phenomena are already at work: on the one hand, the rapid melting of sea ice, and on the other hand, the increase in snow cover in Siberia, in particular.
Melting snow causes a strong warming, as the ocean absorbs more heat, while additional snow in Siberia, reflecting more sunlight, causes it to cool slightly.
In a complex indirect chain reaction, these two developments combined lead to a disturbance in the atmospheric circulation.
The researchers focused on their effect on the polar vortex. These are very strong winds that blow near the pole in winter, are located at very high altitudes, in the stratosphere (the atmosphere consists of the troposphere, in which we live, and then the stratosphere directly above it).
Normally, the polar vortex forms a circle capable of containing cold air.
But under the influence of climate change in the Arctic, it weakens and becomes ellipticalMatthew Barlow explained.
More importantly, atmospheric turbulence is rising from the ground.
step back Then when they reach the polar vortex, they are directed toward the surface.
This modification is in the depressions movement
pushes the jet stream (Jet in English) to the southThe researcher explains. The jet stream is an air current that blows from west to east.
And when you push the jet stream south, it brings cold air with it.
The strength of this study is that it combines two approaches. First, an analysis of direct observations made over the past forty years.
The researchers chose the periods when the polar vortex was stretched in an elliptical shape: thus they noted that before each of these episodes, temperatures changed more markedly in the Arctic, for example due to snowfall. . And in the weeks that followed, it was much colder in North America.
Next, they used a climate model to check the cause-and-effect relationship by varying various parameters.
It is better to anticipate colds
This discovery could have several implications.
First, identifying this mechanism could make it possible to better anticipate extreme cold waves,
Maybe a few weeks agoMatthew Barlow hopes.
This work also shows that it is necessary to better prepare for the possibility of very cold waves, even if the globe is generally warming.
Second, the researchers hope that this warning will help residents realize the global impact of the climate crisis, and therefore the need to fight it by reducing greenhouse gas emissions.
Arctic climate change isn’t just something polar bears regretMatthew Barlow, Martell.
It can really affect you.
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