When the air outside is cold enough to freeze your skin in a matter of minutes, it can be difficult to realize that climate change is real and that the planet is warming.
However, the winter effects of a phenomenon such as the arctic polar vortex are not signs of slowing global warming and climate change. In fact, scientists are trying to determine if the polar vortex’s frequent intrusions into lower latitudes – places like North America, northern Asia and northern Europe – could be a side effect of climate change.
“This is an active area of research,” Doug Gilham, a meteorologist with The Weather Network, told CTVNews.ca in a phone interview Tuesday. “The question is, is climate change altering the behavior of the polar vortex?”
The polar vortices at the North and South Poles strengthen each winter and are a key component of Earth’s climate. Each one is a large area of low pressure and very cold air circulating in a westerly direction around a pole – counterclockwise in the Northern Hemisphere, and clockwise in the Southern Hemisphere.
The vortex is held in place by its rotation and a group of strong westerly winds known as the polar jet stream, which act as a buffer between the vortex and the warmer air at low latitudes. The powerful vortex remains in place. The weak eddy seeps into the lower latitudes like a broken egg yolk.
So when part of the polar polar vortex causes very cold temperatures in Canada, it’s not because climate change has reversed or slowed, but because the vortex has become unstable and moved out of place over the pole.
What causes this? Gilham explained that one of the main reasons for the weakness of the polar vortex is the presence of warm, high-pressure air masses.
Sometimes warm air from outside the vortex crawls up the vortex, squeezing it from above into the atmosphere, displacing cooler air.
“By introducing warmer air in the middle and upper levels of the atmosphere into the polar regions, it tends to disrupt, narrow or bisect the polar vortex,” Gillham said.
“It can kind of get stuck out of its usual position. So the full polar vortex can deflect off the pole, but more often than not, it splits or stretches.”
When this happens, parts of the polar vortex can drift into lower latitudes. This is when we feel the extreme cold associated with the polar polar vortex.
Since there is a connection between warm air and a weak polar vortex, scientists are studying whether a warming climate could make the vortices less stable over time.
“In general, the idea is maybe that in a warmer climate, you’re more likely to get these disturbances in the polar vortex,” Gillham said. “Because with a warmer globe, you will often see warmth build up in the polar regions.”
Arctic ice factor
According to Brett Anderson, chief meteorologist and Canadian weather specialist at Accuweather.com, several scientific studies in the past decade have looked at the relationship between climate change, Arctic ice, and the polar vortex.
“Basically, what the studies are trying to show is that because of climate change, we are seeing a steady decline in the extent of Arctic sea ice over the past 20 to 30 years,” he told CTVNews.ca in an email Thursday.
The US National Oceanic and Atmospheric Administration (NOAA) Arctic 2022 Report Card warns that Arctic sea ice coverage has been steadily declining since 1970, and that annual air temperatures in the Arctic from October 2021 to September 2022 were the sixth hottest. It dates back to 1900. In fact, the seven warmest years in the Arctic since 1900 were the last seven years.
In this file photo filed July 22, 2017, a polar bear is seen climbing out of the water to walk on ice in Franklin Strait in the Canadian Arctic archipelago. Climatologists point to the Arctic as the most visible location for climate change with massive sea ice loss, Greenland ice sheet melting, receding glaciers and thawing permafrost. The Arctic has warmed twice as fast as the rest of the world since 1988 (AP Photo/David Goldman, File)
Because of its brilliant color, sea ice reflects the sun’s energy farther from Earth’s surface than darker-colored open water. As Arctic sea ice melts, it is being replaced by larger areas of open water, which are more likely to absorb the sun’s energy. Anderson said this is one reason the Arctic is warming “at least three times as much” as the rest of the planet.
“Warmer air is less dense than cooler air, so more of this ‘warmer’ air rises into the atmosphere over the Arctic,” he said. “As more air rises, we may see an increase in air pressure higher in the atmosphere, which could lead to a weakening or displacement of the high-level polar vortex.”
Both Anderson and Gilham agreed that there are many gaps in scientists’ knowledge about how the polar vortex behaves in the Arctic. Some years, this behavior defies their theories.
For example, there have been years with very little sea ice and a strong polar vortex and years with a lot of sea ice and a weak polar vortex.
Gilham noted that there were several “epic” Canadian winters in the late 1970s influenced by the weak polar vortex at a time when climate change was much less severe than it is now.
“We’ve been very affected by the polar vortex, and that was really before climate change was a big discussion,” he said. “So the polar vortex can definitely survive the winter, regardless of climate change.”
Both meteorologists said the science suggests we might see the frequency of weak polar vortices change with a warmer climate, but there’s still a lot scientists don’t know.
“There is still a lot to learn about this relationship,” Anderson said. “There’s clearly a lot of changes happening across the Arctic, and there’s no doubt that those changes are having an impact on weather patterns farther south.”