Climate change a factor but not entirely to blame for winter weather

Feb. 28—Although the winter storms Oklahoma has been faced with over the last couple of months have been abnormal and unprecedented, climate scientists and meteorologists say that climate change is not entirely to blame, at least not yet.

Gary McManus, the state climatologist at the Oklahoma Climatological Survey, said it's not uncommon for Oklahoma to experience cold winter storms, but the extent and extreme nature of the cold temperatures this month were rare.

"[Winter storms] happen every few decades," McManus said. "So it's happened before, it'll happen again. But to put this specific event into the context of climate change is a little bit more difficult. You really want to look at a series of these types of things happening on a more frequent basis."

During the winter storm Oklahoma experienced in February, Oklahoma City set the record for the lowest temperature recorded in the state since 1899 when it dropped to -14 degrees Fahrenheit, Vivek Mahale, a meteorologist at the National Weather Service in Norman, said.

"The cold air usually builds up in the north and sometimes it actually crosses the North Pole and comes from across Russia on the other side of the globe and it crosses the pole and then it comes down from the north," Mahale said. "So the cold air just kind of built up there.

"[Looking] at the weather we had before that cold air, it was actually not too bad. We didn't really have a lot of arctic air come down earlier this season. So the cold air just kept on building across the poles and then eventually it just dislodged as the right cold front came through and that front just dislodge that cold air down south into the southern plains."

McManus said this has to do with the warming of the polar ice caps and the consequent weakening of the jetstreams, which then allows the cold air to spill into the southern parts of the northern hemisphere.

"So as the jetstream gets weaker, that cold air that's bottled up around the polar region is allowed to spill down into the South," McManus said. "Then it gets stuck there for a longer period of time than what's normal due to the blocking patterns in the atmosphere. That is one of the things that climate scientists are looking at as a possible culprit in some of these events that have been occurring over the last few decades, like the tremendous floods and the tremendous cold air outbreaks that have been occurring."

Due to the jetstreams weakening, the weather patterns get stuck here for a longer period of time and don't move along as it normally would, he said.

"As the Arctic warms, that temperature difference gets a little bit less and therefore, due to the mechanics of the atmosphere and how the temperature differences, that creates pressure differences and the jetstream [begins] to break down a little bit," McManus said. "But again that allows that cold air to escape down in the south and then it gets stuck here like it did this last couple of weeks."

This weakening of the jetstream won't just result in longer cold spells. It could cause any number of abnormal weather events to be longer than usual, he said.

"It wouldn't have to be any certain event. It could be a long-lived cold weather event or it could be a long live heatwave like we saw in 2011, which ended up as the hottest year on record in Oklahoma dating back to 1895," McManus said. "... So, I think it's been attributed to other types of things again like drought patterns, heat waves and other types of extreme weather. That is what [we] would be looking for when we talk about this theory about the science of the weather patterns getting sticky due to a weakened jet stream."

McManus said that he believes this all still needs to be researched and is not 100% definitive at the moment.

"One thing we need to emphasize as climate scientists [is looking] at this possibility of the weakening of the jetstream at times and the sticky nature of the weather pattern that's still something [we're looking] at. I don't think it's definitive at this time," he said. "It's something that's going to require more studies and more observations before that becomes a more concrete area of science."

Reese Gorman covers COVID-19, local politics and elections for The Transcript; reach him at rgorman@normantranscript.com or @reeseg_3.