The city of Buffalo was particularly affected by the storm that hit the US over the Christmas weekend this year.
Keystone/AP Photo/Craig Ruttle
On the other hand, other mechanisms such as the effect of climate change on the polar vortex and jet stream are not subject to consensus. The polar vortex is a mass of air above the North Pole, located high in the stratosphere (we live in the troposphere and the stratosphere lies above it).
It is surrounded by a rotating gyre, which acts as a barrier between the cold northerly winds and the milder southerly winds. But as the polar vortex weakens, this air wave begins to waver and take on a more oval shape, bringing colder air further south.
And more and more often
According to a 2021 study, these types of disturbances are frequent and reverberate over the next two weeks in the atmosphere where the jet stream is located.
This west-to-east flow of air, again following the boundary between cold and warm air, then bends to allow cold air from the north to penetrate lower latitudes, particularly in the eastern United States.
Disturbances of this type occur frequently, and are reflected in the atmosphere where the jet stream is located during the following two weeks.
Keystone/AP Photo/Jeffrey D. Barnes
“Everybody agrees that severe winter storms are more likely if the polar vortex is disrupted,” study lead author and study climatologist Juda Cohen told AFP. Atmospheric and Environmental Research (AER).
This “stretched” polar vortex was observed just before the storm that hit the US this December, he pointed out. In February 2021, when freezing cold weather hit Texas, a massive power outage occurred.
“Active Discussion”
But the heart of the debate lies elsewhere. The key question is what accounts for these increased polar vortex perturbations?
According to Judah Cohen, they are linked to changes in the Arctic accelerated by climate change: on the one hand, the rapid melting of sea ice and, on the other, the increase in snow cover in Siberia. “It’s a subject I’ve been studying for more than 15 years, and I’m more convinced today by this link than I’ve ever been,” he told AFP.
However, this last point remains “an intense debate within the scientific community,” Michael Mann underscored. “Climate models still do not capture all the fundamental physics relevant to how climate change affects jet stream behavior.”
Future studies are still needed in the coming years to unravel the mystery of these complex chain reactions.
TTY
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