Winter is here in the Northern Hemisphere. The hats and gloves are out, and the snow has begun to fall.
And like clockwork, every time the temperature drops, climate deniers like to come out of the woodwork to ask their favorite question: “It’s cold out! The snow is piling up! Where’s all that global warming and climate change you keep talking about, huh?”
It’s as predictable as the sunrise – and everyone who understands the science knows it’s a bogus, reductive argument, one often presented in bad faith by people who know better. But it’s also hard to fault everyday people unfamiliar with climate science, the differences between climate and weather, and the less obvious impacts of the crisis for asking it too.
So to those seeking an answer to that same question in good faith, we have answers.
The climate crisis is changing winters as we know them. Except the result is far more complicated than global climate change = the end of winter. Indeed, if you’re seeing more heavy lake-effect snows or are biting your nails in fear of the words “Polar Vortex” popping up on your weather forecast, you can maybe blame the climate crisis.
Weather and Climate
Let’s get this out of the way right up top: Winter weather is just that – weather. Weather describes what’s happening at a particular moment in time and in a particular place. Weather can change minute by minute, hour by hour, day by day. Climate, on the other hand, is the average weather over time, usually 30 years or more, and space.
Climate is also relatively stable, or at least it had been for much of human history – until relatively recently for some weird reason.
That relative stability is why we have a pretty good idea of what will happen broadly with temperatures each season – because we saw it happen about this time last year. And the year before that. And the year before that.
But the climate crisis is flipping the script and throwing our natural systems out of balance. And it’s impacting our winters just as surely as it is our summers, even if those effects become ever so slightly more difficult to see between the gently falling snowflakes.
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Overall, Winters Are Warming
Around the world, temperatures are going up.
Carbon pollution from burning fossil fuels like coal, oil, and natural gas is warming our planet and driving climate change. During the summer months, the effects of this warming are becoming more and more plain.
Fairly recently, we concluded a truly record-breaking hurricane season in the Atlantic, one likely to be best remembered for the rapid intensification of several storms due to far-warmer-than-normal waters in the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico. Not to be outdone, devastating wildfires brought on by long-lasting drought and extreme heat burned millions of acres across the American West and Arctic.
It’s happening in the winter too – even if it can seem less apparent in places still contending with traditional winter weather. In fact, in many regions, winters are actually warming faster than any other season.
Climate Central reports that winters across the contiguous US have warmed by an average of nearly 3 degrees Fahrenheit over the last half century. And northern states are seeing an even larger impact, with over 5 degrees Fahrenheit of average winter warming in Alaska, Minnesota, Vermont, and Wisconsin.
But here’s the thing, and it’s vital to understand: “less cold” does not mean “never cold.”
So don’t take the bait when a denier – maybe one with an interest in protecting fossil fuels, for instance – tries to present a snowball, made outside in a location where winter snow is fairly common, as evidence that climate change isn’t real.
While the snowline may indeed be slowly inching poleward, most places accustomed to snow are likely to continue seeing it – how much they’ll see and for how much longer, however, is a more complicated question.
Winter Precipitation and Climate Change
“It may seem counterintuitive, but more snowfall during winter storms is an expected outcome of climate change,” according to the Environmental Defense Fund. “That’s because a warmer planet is evaporating more water into the atmosphere. That added moisture means more precipitation in the form of heavy snowfall or downpours.”
Consider the example of the US Great Lakes.
Cold early winter air flowing over still-relatively warm, unfrozen lake water has forever been the primary driver of the heavy lake-effect snows that blanket parts of the Great Lakes region most years. Some call this phenomenon the “lake-effect snow machine.” But the warming climate across the region is leading to even warmer lake temperatures and later and later freeze-up of the lakes. That’s revving up the “machine” and extending the length of time it may occur each year.
The bottom line: Warmer lake temperatures mean more moisture in the air from evaporation, and when the weather cools that’s providing the fuel for truly gargantuan snowfalls that are continuing deeper and deeper into the winter than they previously had.
And while it’s often difficult to assign full blame to climate change for any given weather phenomenon, consider this report from February 2020, taken from a Weather Channel article headlined, “Over 500-Mile Long Lake-Effect Snowband Hammered New York's Lake Ontario Snowbelt With Up to 4 Feet of Snow”:
What's unusual about this year is that Lake Erie has less than 1% ice coverage on its surface, due to unusually mild temperatures this winter. In a typical year, ice has covered about 62% of the lake by Feb. 27, according to the 1973-to-2019 average. This open water enhanced the temperature contrast between the surface and the colder air aloft, which supported intense lake-effect snow.
At the same time, many places seeing less and less precipitation on average throughout the year are also seeing that trend carry over into winter. Like a lot of things related to the climate crisis, where you are is key to the impacts you see.
But Warming May Bring Bitter Cold Snaps Too
As our use of fossil fuels continues to warm the climate, a long-term temperature trend has emerged – and it’s pointing steadfastly upward.
But at the same time, weather always has—and always will—fluctuate. There are warm days, mild days, cool days, and even some very cold days. There are dry periods and wet periods. And this will continue to be the case.
But one consequence of climate change may actually help explain a weather phenomenon that, on its face, would seem to have little to do with global warming – the reason why Arctic deep-freezes keep spilling farther and farther south.
A growing body of research indicates that as average global temperatures rise and the Arctic continues to warm, the jet stream is both slowing down and growing increasingly wavy. In the winter months, this is allowing bone-chilling cold Arctic air – typically held in fairly stable place by the once-stronger jet stream – to both spill much farther south than usual and linger over areas unaccustomed to it for longer.
So even as winters on average have been getting shorter and warmer, many places should still expect to see bouts of very cold weather from time and time. At least for now…
- Winters around the world are warming.
- But this warming does not necessarily mean an end to traditional winter weather in many places – at least not yet.
- Extreme precipitation events – including major winter snowstorms and lake-effect snow events – are becoming more common because of climate change.
- Warming in the Arctic may be leading to a less stable jet stream, resulting in frigidly cold air spilling into areas not accustomed to seeing such low temperatures for such long periods.
What You Can Do
It’s our responsibility to do everything we can to prevent the worst of the climate crisis. And it certainly could get much worse.
Acting now to swiftly transition from dirty fossil fuels to clean energy can limit global warming to no more than 2 degrees Celsius (3.6 degrees Fahrenheit). Two degrees of warming could have significant impacts, there’s no denying. But if we do nothing and continue on the path we’re on, the global average temperature could rise by far more than that by the end of the century.
And if that happens, to say you would have just finished reading a very different assessment of what winters will have in store is likely among the understatements of the century.
But it doesn’t have to be like that.
So, are you ready to make a difference for the future of our planet?
It starts with learning more about our Climate Reality Leadership Corps, and getting the skills, knowledge, and network to advocate for a better, more-just tomorrow for all at our upcoming virtual US training. The event will be held April 22 through May 2, and is designed for US residents with content specific to US climate science and sessions timed around US working hours. Register now.
Before You Go
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