The world is getting warmerincluding winters.
(See: The number of deaths from storm Elliot in the US rises to 50).
However, The United States has experienced severe winter storms in recent years, and experts are taking a closer look at the link between these episodes of extreme cold and climate change.
Unlike the relationship between global warming and heat waves, which is very direct, the behavior of winter storms it is governed by complex atmospheric dynamics that are more difficult to study.
Even so, “There are certain aspects of winter storms (…) where the links to climate change are quite clear,” said to the AFP Michael Mann, a climatologist at the University of Pennsylvania.
For example, warming of water bodiessuch as lakes or oceans, influences the amount of snow falling.
(See: Christmas storm in the United States leaves at least 26 dead).
In the United States, the ‘lake effect snowfall’ occur around the Great Lakes region, in the border with Canada.
the city of buffalowhich is located on the banks of one of the great lakes, was hit hard by a deadly snowstorm over Christmas weekend.
The clash between cold air coming from the north with the warmest water from these lakes causes convection, which causes snowfall.
(See: How do I know if my flight to the United States was cancelled?).
“The warmer the lake temperatures, the more moisture (there is) in the air and the greater potential for lake-effect snowfall”Mann wrote in a 2018 article.
“Unsurprisingly, we see a long-term increase in lake-effect snowfall as temperatures have increased over the past century,” explained.
However, USA has experienced severe winter storms in recent years, and experts are taking a closer look the link between these episodes of extreme cold and climate change.
There is, however, no consensus on other mechanisms, such as the effect of climate change on the polar vortex and jet air currents.
The polar vortex is an air mass above the North Polelocated high in the stratosphere.
Humans they inhabit the troposphere and the stratosphere lies just above it.
This vortex is surrounded by a band of rotating air, which acts as a barrier between the air cold from the north and warmer air from the south.
As the polar vortex weakens, this band of air begins to undulate and acquires a more oval shape, bringing more Cold air to the south.
Snowstorm in the United States.
EFE
According to a 2021 study, this type of disturbance is occurring more frequently and, when it occurs, it reverberates for the next two weeks further down in the atmosphere, where the jet stream.
This air current, which blows from west to east, again following the border between cold and warm airthen meanders in such a way as to allow cold air from the north to descend to lower latitudes, particularly over eastern USA.
“Everyone agrees that when the polar vortex is disturbed, the likelihood of severe winter weather increases,” Judah Cohen, lead author of the paper, told AFP. study and climatologist from the Atmospheric and Environmental Research (AER) analysis center.
And this polar vortex ‘stretched’ is exactly what was observed just before the storm that hit the United States this December, he noted.
(See: New York asked to be declared a winter storm disaster area.)
The same phenomenon was observed in February 2021, when a strong cold wave it hit Texas and caused massive power outages.
But the center of the debate is on a key question: what is causing these increasing disturbances in the polar vortex?
According to Cohen, these alterations 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.
“This is a subject that I have been studying for more than 15 years and today I am more sure than ever of that link”he told AFP.
However, this last point remains a ‘ongoing discussion’ inside of scientific community.
“Climate models still do not capture all the underlying physics that may be relevant to how climate change is affecting jet stream behavior,” accurate.
Therefore, more studies will be needed in the next years to unravel the mystery of these complex chain reactions.
AFP
