As the United States experiences severe winter storms in recent years, experts are taking a closer look The link between these episodes of extreme cold and global warming.
and that is, the opposite of the relationship between global warming and heat waves Which is pretty obvious, the behavior of winter storms is governed by complex atmospheric dynamics that are more difficult to study.
yet it is “There are some aspects of winter storms (…) where the links to climate change are quite clear,” says Michael Mann, a climatologist at the University of Pennsylvania.
For example, he heating of water massLike lakes or oceans, affect the amount of snow that falls.
In the case of the United States, “Lake Effect Snow” They are found around the Great Lakes region, on the border with Canada. The city of Buffalo, which sits on the shores of one of the Great Lakes, was hit hard by a deadly snowstorm over the Christmas weekend.
This is because cold air from the north collides with the warm water of these lakes to cause convection, which leads to snowfall.
“The warmer the lake temperature, the more moisture in the air and the greater the likelihood of lake-effect snowfall,” Mann wrote in a 2018 article.
“As thought We see a long-term increase in lake-effect snow as temperatures rise in the last century,” he explained.
In-spite of this, There is no consensus on other mechanisms that cause winter storms, such as the effects of climate change. In the polar vortex and jet air streams.
polar vortex and climate change
The polar vortex is an air mass above the North Pole, located high in the stratosphere. Humans reside in the troposphere, and the stratosphere is located just above it.
it is Cyclone It is surrounded by rotating bands of air, which act as a barrier between cold air from the north and warm air from the south. As the polar vortex weakens, this band of air begins to ripple and becomes more oval in shape, bringing more cold air to the south.
According to a 2021 study, this type of disturbance occurs more frequently, and when it does, it echoes further down in the atmosphere, where the jet stream is located, for the next two weeks.
This air current, which flows from west to east, again follows the boundary between cold and warm air, then dissipates as cold air from the north descends at lower latitudes, especially in the eastern United States.
and this polar cyclone What is troubling is what Judah Cohen said just before the hurricane that hit the United States this December Atmospheric and Environmental Research (AER). The same phenomenon was seen in February 2021, when a severe cold snap hit Texas, causing widespread power outages.
According to Cohen, these changes are related arctic transformation, accelerated by climate change. Rapid melting of sea ice on the one hand and increase in snow cover in Siberia on the other. However, this remains an “ongoing debate” within the scientific community.
“Climate models still do not capture all of the underlying physics that may be relevant to how climate change is affecting jet stream behavior,” he said.
Therefore, more studies will be needed in the coming years to unravel the mystery of these complex chain reactions.