Not sure if you’ve noticed this, but it’s cold outside. It’s been cold for a while now — we haven’t been above freezing since Christmas — but now it is really cold. The briefly insulating snow has given way to a citywide luge course, as the temperature has quickly dropped into the single digits. Wind gusts are approaching 50 miles per hour. Heaps of frozen rats are piling up in the streets. Even Craigslist’s hot singles are afraid to go outside.
Like clockwork, cold spells like this tend to bring out the armchair climatologists, eager to point to the frigid temperatures as evidence that global warming is a myth. Oklahoma senator Jim Inhofe famously brought a snowball onto the Senate floor to back up his well-funded climate denialism. Last week, President Trump, whose so-called winter White House may soon be underwater, capped off his first year in office by suggesting that the East Coast “could use a little bit of that good old Global Warming.”
Putting aside our president’s inability to distinguish weather from climate, it’s worth exploring the ways in which global warming may be disrupting our atmospheric conditions. According to one increasingly popular theory, climate change may actually be contributing to these bone-chilling conditions.
The explanation for this counterintuitive pattern can be found in the Arctic, where temperatures are rising twice as fast as in the rest of the globe. Known as Arctic amplification, this astonishing phenomenon is the result of a feedback loop specific to the region, in which melting ice exposes the dark ground and ocean beneath it, which in turn absorbs more sunlight. The record for this amplification was smashed in 2016, and 2017 looks likely to come in second. But while scientists have observed this dramatic thawing for years, it’s only recently that some have started to connect that process to extreme cold snaps like the one we’re currently experiencing.
“A growing body of research suggests that the rapidly warming Arctic is causing the jet stream to take larger north/south swings, thereby leading to so-called amplified patterns occurring more often,” Jennifer Francis, a research professor in the department of Marine and Coastal Sciences at Rutgers University, tells the Voice.
Recent studies by Francis and other scientists have advanced this theory, which links extreme weather temperatures in the Northern Hemisphere to the ongoing weakening of the polar vortex — a widely misused term, Francis notes, that actually refers to the circular zone of frigid air in the stratosphere above the North Pole. When that weakened polar vortex interacts with the jet stream below, as is the case right now, Arctic air may be pushed south in our direction.
“So if the jet stream takes a big dive southward, as it does when it’s very wavy, Arctic air dives southward with it,” explains Francis. There’s also a resulting swing in the opposite direction that may be less obvious to us East Coasters, allowing warm air to penetrate far north, “which is why Alaska has been very warm so often this winter,” according to Francis.
The meteorology behind this can get complicated, but the underlying explanation for how jet streams travel is fairly straightforward. These bands of wind get their strength when air moves from high- to low-pressure areas, which are dictated by the boundary of warm and cold air. (Cold air is denser than warm air.) So when the temperature gap between the equator and the North Pole lessens, the jet stream weakens, and starts acting crazy.
“If you think of a river moving rapidly down a sleep stope, it’s going to go pretty straight,” explains Ben Orlove, a senior research scientist at the International Research Institute for Climate and Society and a professor at the Columbia School of International and Public Affairs. “If you think of it moving across a flatter area it’s going to meander, which is what we’re seeing in the jet stream.”
Orlove adds, “I don’t want to say that everything bad is climate change, but we know the Arctic is warming and it’s having an effect on the jet stream.”
To be clear, there’s no scientific consensus on how, exactly, global warming will affect winter weather patterns. Predictions are difficult, particularly when, as one science writer puts it, the Arctic’s air appears to be drunk. But like many wayward drunks, that jet stream is prone to lingering. Beyond the occasional invasion of freezing arctic air, Francis says, we should expect the disrupted jet stream to cause future extreme weather events to last even longer.
“In my view, it’s the persistence that is more disruptive to society than a few days of broken records,” she says. So as you saddle up next to a shrieking radiator, know that global warming won’t fix things, and may indeed be responsible for this Arctic blast — and additional ones in the future that will stretch on for more days at a time. Right now, Francis warns, we’re in “uncharted territory.”