Scientists have discovered that recent cold weather extremes may be linked to global warming, a study published in Science said on Thursday.
Human-caused global warming was expected to lead to more heatwaves and heavy precipitation events, but the increase in cold air outbreaks and heavy snowfalls, most recently in January and February of 2021 in Asia, Europe and the United States, surprised the scientists, leading them to research the connection between extreme cold weather and global warming.
One of the key manifestations of global warming is Arctic warming, otherwise known as Arctic amplification (AA) which causes sea ice to decrease. Because the decline in sea ice increases moisture in the air, AA ultimately leads to heavy snowfall in the Arctic.
The researchers used a machine-learning technique to analyze the weather and discovered that there are frequent increases in sudden stratospheric warmings (SSW), while the strongest states of the stratospheric polar vortex (SPV), which is a semi-permanent pool of cold air over the poles, decrease in January and February.
A follow-up study identified a less-known SPV disruption in which the vortex is stretched, causing more frigid cold spells in the mid-latitudes. The researchers were able to identify cases of SPV stretching as far back as 40 years ago.
The research team showed through climate simulation modeling that changes in Arctic sea ice and increases in Eurasian snowfall, caused by AA, may be causing the SPV stretches, thus impacting extreme cold weather.
The study shows that while global warming is causing a rise in temperatures, extreme cold spells are also possible due to global warming, and while the cold spells are not always guaranteed, they can be devastating when they do occur.
An example of this is February of 2021, when extreme cold weather led to a collapse of the Texas energy infrastructure, resulting in one of the costliest natural disasters in Texas.
This insight provided by the study is yet another warning to the dangers of climate change, which the UN warned is happening more rapidly than expected in a Code Red announcement at the beginning of August.
"We find ourselves in the midst of global warming that was caused as a result of human actions, which is causing the summer to lengthen on the one hand, while causing extreme cold incidents at a higher frequency on the other hand," said Judah Cohen from MIT who led the study.
"The last winter was riddled with extreme cold weather all around the world - Siberia, Europe, Asia and America, with the most memorable being Texas in February, where the damages were valued at about $200 billion. The results of the study show that the fact that earth is warming won't protect us from the destructive forces of harsh winter climate."
"We used observational analysis combined with output from models we ran," explained Professor Haim Garfinkel from Hebrew University, who took part in the study. "We showed that even though globally, there is a decrease in the average of extreme cold event, in the mid-latitudes winter there is a rise, and that stems from a new mechanism. Our study showed that, contrary to popular belief, a month after the beginning of the incident, the effect on North America was stronger. We also showed that this new mechanism is on a rising trend."