Warming Arctic changing jet stream and our weather: expert
Published Tuesday, February 18, 2014 8:40PM EST
Last Updated Wednesday, February 19, 2014 12:55PM EST
When severe storms hit one question that is often asked is if the storm is somehow connected to climate change. Scientists are often quick to point out that storms and weather are caused by the jet stream. It’s sort of like a high-altitude conveyor belt that moves winds and weather from west to east.
But now evidence is starting to mount suggesting the jet stream is taking a wavier trip through the northern latitudes, including North America, and the cause is probably a warming Arctic. Those are the findings of Jennifer Francis, who is a research professor at the Institute of Marine and Coastal Sciences at Rutgers University.
Skip ahead to the 31-minute mark of the video above to see our full interview with Francis.
“This winter was certainly an extreme situation,” she says to Kevin Newman Live from her home near Cape Cod. Since early December a big swing northward over Alaska has been causing an incredibly warm season for the northern most state and is contributing to the drought in California. The jet stream has been weakening and that causes it to meander more as the air moves from west to east. Francis likens it to a river flowing down a mountain. When the water is flowing downhill it takes a relatively straight path, but then when it hits the plains it is travelling slower and meanders more.
Francis presented her findings at the annual meeting of the American Association for the Advancement of Science in Chicago over the weekend.
She says the wavier jet stream has “been blocking the usual storm track from coming in from the Pacific.” That’s been causing the drought. “As it swings back northwards it collects moisture from the Gulf of Mexico and it’s made for quite a snowy East Coast.”
Here’s what the jet stream looks like as it moves around the northern part of the planet. You can see the red and yellow lines increase in oscillation or form bigger waves.
She says areas like southern Ontario or the northeast of the U.S. have been in the part of the jet stream where storms form. That combined with there being more water vapour in the air – also due to the warming oceans – is causing more snow. Because the jet stream is moving slower, we also get trapped in cold spells for longer. Francis says this necessarily won’t make for harsher winters or more severe storms, but when we get snow or cold it will last for longer.
She first proposed the idea in a paper two years ago. Since then she says evidence is piling up. It’s not conclusive and it’s difficult to point to any one season or any one storm as being caused by a warming arctic.
“It’s going to need another decade until people are thoroughly convinced and we get robust statistics from the real world,” Francis says. “There will definitely be years when things seem normal…a lot of other things in the climate system that affect the jet stream besides this rapid warming in the arctic (such as El Niño and various oscillations).”
While we may be hoping for more mild winters in the future, she says we should expect more winters like this one in the future.