I would like to read your prediction of the effects of climate change on the traditional four weather seasons.
From a lifestyle preference, it has been nice for me to know that in the summer, there will be the warmth of the ocean. In the fall, we see the shedding of the leaves and the beauty of the trees when they’re bare. In the winter, there may be snow or outdoor sports. In the spring, we see the wonderful flower gardens that people have planted – and the beauty of that can be predicted.
I ask the question because I have some suspicion that that’s going to change in some way, shape, or form. And I don’t look forward to that.
– Claude in Durham, North Carolina
I’m writing to you in early February, which is still “winter,” at least according to the calendar. But here in North Carolina, it is 70 degrees Fahrenheit, the birds are singing, and the daffodils are bursting into bloom. It’s fittingly bizarre weather for the end of my series on how climate change is affecting the four seasons. (For those who missed it, I’m breaking my answer to Claude’s question into four parts published over the course of a year. Click through to read about the impacts of climate change on spring, summer, and fall.)
Across the United States, winters are already growing warmer and shorter as a result of climate change, and that trend is expected to continue in the future. If you’re a winter-hater, that might sound like fantastic news. But bitterly cold temperatures, snow, and ice are more useful than you might think. Wintry weather – for now – is keeping invasive Burmese pythons confined to South Florida, providing a natural store of drinking water in the West, and reducing the spread of insect pests, among many other useful services.
Here’s a look at how warming winters are affecting the major U.S. regions, except for tropical Hawaii, where seasonal changes function differently than in the other 49 states. These summaries are drawn from the 2018 National Climate Assessment, a sweeping scientific report produced by an interagency government task force.
Ah, winter in New England, when layers of snow shroud the landscape, cats and dogs bask by the fireplace, and the hardiest of Yankees go jogging outside in shorts.
The Northeast is known for harsh, snowy winters, but that reputation could take a hit in the future. Winters there have been warming three times as fast as summers, and the season is expected to become even milder and shorter by mid-century. The region is already experiencing an increase in winter precipitation falling as rain rather than snow, a trend that scientists expect will continue.
That could be a welcome change for people who don’t enjoy – and this is a technical term – freezing their faces off. But it comes with major downsides. In the absence of harsh winters, insect pests such as the emerald ash borer could expand their range and population sizes, posing more problems to the region’s trees.
Shorter, rainier winters are also a threat to the region’s winter recreation industry, worth about $2.6 billion annually. Artificial snowmaking could help skiing and snowmobiling venues stay in business. But unless global warming pollution is sharply reduced, by the end of this century, sports that rely on natural snow and ice will be pretty much kaput in all but the northernmost areas of the region.
Unlike its northern cousin, the Southeast isn’t known for bitterly cold winters. But across much of the region, winters are still cold enough to prevent tropical species from flourishing. Take the Burmese python, a large invasive species known for killing native wildlife in the Everglades. Burmese pythons can be killed by freezing and near-freezing conditions, so their range appears, for the moment, to be confined to Florida.
That could change.
Winters in the Southeast are already warming up, and the freeze-free season is expected to lengthen. Whole ecosystems could be transformed as a result. For example, mangrove forests could eventually replace salt marshes in some coastal wetlands. And undesirable critters, such as tree-damaging insects and Burmese pythons, could expand their ranges northward. (Burmese pythons are secretive and rarely attack people.)
On the other hand, scientists also expect that citrus crops will survive farther north than they do today. Here’s to ultra-fresh orange juice!
Although winter can still bring bitterly cold weather to the Midwest, the season has been gradually warming, enabling new insect pests and crop diseases to spread farther north in this agriculture-dependent region. In the future, climate change could cause a litany of problems, such as increasing the risk of winter and spring flooding, adding stress to forests, and altering the timing of seasonal water turnover in the Great Lakes – which could unleash cascading changes in the lake ecosystems.
And this sentence from the National Climate Assessment will unsettle those who are tired of shoveling snow: “As the warming in the Midwest continues, reductions in lake ice may increase the frequency of lake-effect snows.”
On the other hand, warmer winters may eventually make some places – the report names upper Michigan and Minneapolis, Minnesota, as examples – more appealing to outsiders. In fact, the Midwest may even see transplants from other regions as its winter climate grows less harsh.
Southern Great Plains
In the Southern Great Plains, winters have already grown warmer and shorter. Cold-sensitive black mangroves are sprouting farther north on the Texas coast.
Warming winters are also driving up water temperatures in Texas coastal waters. That increases the risk of low oxygen levels in the water, a major factor in fish kills. And in more bad news for fish, hotter winters have led to a decline in the southern flounder population in Texas. The reason? Warmer water temperatures “masculinize” flounder – creating populations that contain far more male than female fish. The world is a deeply weird place.
Northern Great Plains
The Northern Great Plains boast spectacular landscapes and the incredible outdoor activities to go with them. In this region, which includes Montana, Wyoming, both Dakotas, and Nebraska, fishing, hiking, snowmobiling, cross-country skiing, and downhill skiing are popular pastimes.
But climate change is a threat to all of that. Warming temperatures are causing shorter snow seasons, a trend all-but-certain to continue in the future. Even if global warming pollution is sharply reduced, by 2050, the snow season is expected to end about 20 days earlier than it did in the past. That’s an ominous outlook for the region’s winter recreation industry.
It’s also a problem for fishing. In the past, slowly melting snowpack kept rivers and streams cool in summer. But with declining snowpack and rising air temperatures, that water is getting warmer, increasing the risk of disease in cold-water fish. In 2016, Montana officials banned all water-based recreation along 180 miles of the Yellowstone River for a month after a temperature-linked disease caused an unprecedented fish kill.
Hiking in the region may fare better, though some views may be less stunning. In Wyoming and Montana, warmer winter and fall temperatures, in combination with reduced summer precipitation, are fueling booms in mountain pine beetles – notorious killers of the region’s iconic whitebark pines.
Each spring in the mountains of the Southwest, water from melting snow flows into the Colorado, Rio Grande, Sacramento, and other rivers. Vast infrastructure, such as the Oroville Dam in California, is designed to capture that water for use in irrigation, electricity generation, and as drinking water.
If people keep releasing heat-trapping carbon pollution at current rates, some of that snowpack is likely to disappear – and quickly. The mountain ranges in California that receive winter snow today could see only rain by 2050. Other mountainous areas across the West will also receive more rain instead of snow, though snow will still fall in high-elevation areas.
If those precipitation shifts result in water shortages, agriculture in the region could suffer. What’s more, some crops – such as cherries, apples, peaches, and plums – require cold winter weather to fruit properly, so yields could fall. Peaches?! As a person named after this fruit, I take that personally.
When it comes to winters in the Northwest, scientists predict that the weather will become less predictable. Got that?
Let’s start with mountain snowpack, which many Northwest residents rely on for everything from drinking water to irrigation to electricity from hydropower, not to mention outdoor recreation activities such as skiing and snowmobiling. With warming winters, Western mountain snowpack has been gradually declining, which also increases the risk of wildfires.
Scientists are also studying the effects of climate change on atmospheric rivers, which are plumes of moisture that cause heavy rain. Extreme rainfall from atmospheric rivers is expected to occur more often in the Northwest in the coming decades, and severe winter storms are expected more frequently along the coast.
Scientists expect that on average, winter precipitation will increase in the Northwest, but that it will be less consistent than in the past. Weather extremes at both ends of the spectrum – droughts and floods – will become the new normal.
In Alaska, warming winter temperatures have been good at least for one thing: reducing the winter costs of heating homes, businesses, and government buildings.
But warmer winters have brought other unwanted consequences. For example, many Alaskans get around in the winter by driving on frozen rivers, which are known as ice roads. But unusually warm weather and shorter ice seasons are causing the ice roads to melt ahead of schedule. In some cases, people have been injured or died as a result.
The loss of permafrost and sea ice has left some coastal Alaskan villages with less protection from fall and winter storms, leading to severe erosion and flooding. Residents of Newtok, in eastern Alaska, have already begun relocating to a new inland village.
I’ll leave you with one final disturbing factoid. Scientists also warn that continued warming could prove beneficial to parasites and diseases: “Climate change may allow some parasites to survive longer periods, provide an increase in the annual reproduction cycles of some disease-carrying insects and pests (vectors), or allow infected host animal species to survive winters in larger numbers, all increasing the opportunity for transmission of infection to humans,” the authors of the National Climate Assessment warn. Yuck!
Tom Toro is a cartoonist and writer who has published over 200 cartoons in The New Yorker since 2010.
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