How a warming Arctic speeds up climate change — and spreads its damage
As more and more carbon dioxide is pumped into the atmosphere, it warms the planet. And nowhere are the effects more dramatic than in the Arctic.
"In Canada's Arctic, in the period of more or less the last 40 years, we've lost about 40 per cent of ice coverage," said Blair Feltmate, head of the Intact Centre on Climate Adaptation at the University of Waterloo.
The problem with that is, the ice and snow up there reflects about 80 per cent of the sun's radiation. But that warmth causes it to melt, exposing dark water that only reflects 20 per cent. So the cycle only intensifies: less ice and snow causes more warming; more warming causes less ice and snow.
"The loss of ice in the Arctic has actually caused a positive feedback system whereby climate change is driving climate change in and of itself, on top of the burning of fossil fuels," Feltmate said.
According to the U.S. National Snow and Ice Data Center, winter ice cover in the Arctic has decreased by roughly three per cent per decade since 1979. In 2012, there was a record low for minimum ice cover in September, 3.41 million square kilometres — 44 per cent less than the 1981–2010 average.
The warmer temperatures in the region also produce thinner ice, which contributes to the feedback loop in its own way.
The thinner ice breaks up much easier and is more mobile, said Jennifer Francis, a research professor at Rutgers University in New Jersey who studies climate change in the Arctic.
"So any abnormal wind that comes along can shove it along to one side and move it around much faster," she said. "And that exposes a lot more open water to the atmosphere, so we get a lot more heat transferred from the ocean to the atmosphere."
A third contributing factor to the feedback system is the release of methane from the melting permafrost. Methane gas traps more heat than carbon dioxide. More warming causes more methane in the atmosphere; more methane in the atmosphere causes more warming.
The recent report from the Intergovernmental Panel on Climate Change found warming in the Arctic is happening two to three times faster than anywhere else on Earth. And the consequences of this warming will be felt across the globe — because what happens in the Arctic doesn't stay in the Arctic.
The warming Arctic has its most significant impact on the jet stream, a column of air in the upper atmosphere that helps drive weather systems.
Scientists have noticed that the jet stream, which used to move in a relatively straight line from west to east with few dips, is now more unstable, with much bigger dips.
This moves Arctic air farther south — think of the — and allows warmer air from the south to move farther north.
Just this week, for example, parts of Alberta were battling abnormally low temperatures and snow, while southern Ontario was basking in record summer-like temperatures.
"Those north-south waves in the jet stream are what creates the weather … so anything that affects the jet stream affects the weather," Francis said.
And that includes the weather across the entire Northern Hemisphere.
Take, for example, Hurricane Florence that almost came to a standstill over the Carolinas last month. Because the jet stream was so far north, the hurricane was cut off and prevented from moving northeastward on a more typical path. It was similar to what occurred with Hurricane Harvey in 2017 over Texas.
"We're talking about an integrated system," Feltmate said. "When you have disproportionate warming in the Arctic region going forward, the manifestation of that phenomenon at a global scale is going to be felt effectively all over the planet."
However, as the IPCC report makes clear, there is a significant difference between a planet that has warmed by 1.5 C above the pre-industrial average and one that has warmed by 2 C. For one, an ice-free Arctic is forecast to occur one summer per century at 1.5 C warmer. At 2 C, that jumps significantly, to one summer per decade.
"There's not a whole lot we can do to reverse it. But it doesn't mean we shouldn't do everything we can possibly do to slow it down," Francis said.
"The underlying disease is emissions of greenhouse gases."