The mid February snow storm in Texas raised questions for everyone, including scientists like Prof. Flavio Lehner, earth and atmospheric science. Lehner explained that the SSW that occurred in late January was a result of a 100 degree spike in temperature in the earth’s stratosphere, which led to unstable polar vortices and abnormal weather patterns.
“The polar vortex is cold air up in the Arctic that carries a strong current,” Lehner said. “It’s always there in the winter. No one thinks about it because it doesn’t bother us.”
To paint an image of what links these independent stratospheric characteristics, Lehner likened the polar vortex to a bathtub.
During the winter, when the Northern Hemisphere is tilted away from the sun, the tub — that is, the region of the stratosphere where the polar vortex lies — wobbles and is constantly churning, Lehner explained.
“Weather events happening at lower latitudes at the surface of the Earth that bump against the tub make it unstable,” Lehner said.
Because of weather events such as SSWs, the cold air of the vortices spills over the Americas, resulting in snow storms. Where the storm system lands occurs by chance, according to Lehner.
Since SSWs blur the difference in weather between the stratosphere and troposphere, the two layers of the atmosphere closest to the Earth’s surface, scientists have started to consider the relationship between anthropogenic climate change’s effects on the troposphere and the stability of the polar vortex in the stratosphere.
But according to Lehner, scientists still need more evidence to evaluate the hypothesis that climate change is driving polar vortex instability and abnormal winter weather.
“The importance of answering that hypothesis is actually quite high,” Lehner said. “In Texas, for example, infrastructure is not prepared for these outbreaks, even though they’ve happened in the past.”
Lehner suggested that despite the uncertainty about the cause of SSWs, investigating the climate change hypothesis will allow for improvements in atmospheric modeling, as well as better preparation for future occurrences of devastating weather.
Though the extreme winter weather has largely settled, the Texas storms come as the latest in a string of climate change-related weather events impacting the country that reveal the potential for deviations from normal weather patterns for years to come.