This weekend, some 200 million Americans will be cranking up the thermostats in their natural-gas-heated homes, firing up their propane generators, or hitting icy roads in their combustion-engine cars as a major winter storm brings record-low temperatures to 35 states, knocks out power, and grinds air travel to a halt.
Climate change deniers love to use major winter storms as “proof” that global warming isn’t real. But in the case of this weekend’s polar vortex, there is evidence that Arctic warming is responsible for the record cold temperature projections across the United States.
“In the Arctic, in the winter, the ocean is much, much warmer than the atmosphere,” Judah Cohen, a climatologist at MIT and the author of a 2021 paper linking Arctic variability to extreme weather in the U.S., told me. Sea ice acts as an insulating layer separating the warmer ocean water from the frigid air. But as it melts — as it is doing every month of the year — “all of this heat can now be extracted out of the ocean.” The reduced temperature difference between the ocean and atmosphere creates wavy high-pressure ridges and low-pressure troughs that are favorable to the formation of polar vortices, which can funnel extreme cold air down over North America, as they seemingly did over Texas in 2021’s Winter Storm Uri, when 246 people died.
The exact mechanisms and interactions of this phenomenon are still up for debate. “I am in the minority that argues that there is causal link between a warm Arctic and cold continents,” Cohen added to me via email. “Most others argue that it is a coincidental relationship.” Still, scientists generally agree that extreme cold events will persist in a warming world; they’ll just become rarer.
Cold kills more people in the United States than heat, but curiously, warmer winters aren’t likely to significantly reduce these seasonal deaths. That’s because about half of the cases of excess mortality in winter are from cardiovascular diseases, which are, by nature, “highly seasonal,” Kristie Ebi, a professor of global health at the University of Washington, told me. “Since people began studying these, there are more of them in the winter than there are in the summer.” Researchers still aren’t sure why that is — though since the 1940s, we’ve known that people’s blood pressure, cholesterol, and even blood viscosity go up during the colder and darker months, perhaps due to changes in diet or exercise. That also appears to be the case regardless of climate or temperature, holding true whether you’re in Yellowknife or Miami.
In other words, “if seasonal factors other than temperature are mainly responsible for winter excess mortality, then climate warming might have little benefit,” Patrick Kinney, the director of Columbia University’s Climate and Health Program, wrote in Environmental Research Letters back in 2015. Extreme heat-related deaths, by contrast, have no ceiling, meaning global warming will result in more temperature-related deaths than it will prevent.
Our anthropogenically warmer winters could even prove to be more deadly in certain ways. Dana Tobin is a researcher at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder who studies how weather affects traffic accidents. She’s found that driving in freezing rain is more dangerous than driving in snow “because of the ice glaze that it can produce on surfaces, especially those that are untreated,” she told me. As winters become warmer, there will, counterintuitively, be more ice on roads in many places, since freezing rain requires a bit of warm air before it hits the ground and becomes black ice.
Researchers working in Scandinavia have similarly found that as the atmosphere warms and more days hover around freezing, “there is a higher risk of icy conditions … which may lead to a predisposition to falls and road traffic accidents.” (As I’ve previously reported, milder winters might also make us even more depressed than very cold ones.)
There is something slightly karmic about the fact that cars become increasingly unsafe as the planet, warmed by their emissions, becomes more hazardous. But this connection gets even bleaker when carbon monoxide poisoning is factored in.
On Thursday, the North American Electric Reliability Corporation issued a statement warning that “much of North America is at an elevated risk of having insufficient energy supplies to meet demand in extreme operating conditions,” including “advancing winter weatherization of power plants and fuel acquisition to enable operations during cold temperatures.” Heavy ice can also snap branches above power lines, causing local outages.
When the power goes out or the gas lines freeze, desperate people will do anything to stay warm. That includes, in tragic cases, running improperly vented generators or plugging in propane heaters indoors, which can produce odorless and colorless CO — instead of the usual water and carbon dioxide — when fossil fuels don’t burn correctly. Accidental carbon monoxide poisoning is on the rise in the United States due to the proliferation of such appliances amid increasingly frequent extreme weather events, jumping 86% between 2012 and 2022. That’s even as, worldwide, carbon monoxide poisoning is decreasing.
Snow and ice are among the most dangerous weather conditions in the U.S., and people should take warnings of “life-threatening conditions” at face value. Tobin, the traffic researcher, stressed that one of the best protections from winter weather hazards is knowledge alone. “I believe the best thing that we can do when it comes to messaging to protect drivers from hazards is to empower motorists to make educated and informed decisions for their own safety and the safety of others,” she told me.
Winter storms highlight the entangled nature of our dependence on fossil fuels. We can’t separate extreme weather events from the energy required to survive them. But the dark irony is that, as the planet becomes more volatile, the most dangerous fossil fuels might be the ones meant to keep us warm and get us back home.
Projected increases (purple) and decreases (green) in excess deaths due to temperature in a warming Europe. 
