Across much of the Northern Hemisphere this year, winter was a shadow of its former self — and climate change is partly to blame.
According to data released Wednesday by the Copernicus Climate Change Service, Europe’s average temperature for December through February was 6.1 degrees Fahrenheit above the 40-year average, shattering the previous record by more than two degrees. In the United States, temperatures were above average for every state but Alaska.
The season was the second-warmest on record for the globe as a whole — putting 2020 on track to be one of Earth’s top-10 hottest years.
This winter weirdness was in part driven by normal variations in global weather patterns, scientists say. But climate change, which tilts the planetary scales in favor of high-temperature extremes, exacerbated the variation and makes future warm winters more likely.
Karsten Haustein, a meteorologist at the University of Oxford, said climate change was the “only way to explain” these extraordinary highs. As long as humans continue to emit planet-warming gases, he added, winters as we once knew them will be fewer and farther between.
A Washington Post analysis of global temperature records has found that 10 percent of the planet has already warmed by more than 3.6 degrees Fahrenheit (2 degrees Celsius) since the end of the 19th century. The majority of these new hot spots are at far northern latitudes, where winter tends to be the fastest-warming season.
The past three months, a weather pattern known as the Arctic Oscillation caused a powerful polar vortex in the upper atmosphere, keeping cold air bottled up over the North Pole. Ripples in the vortex that cause winter’s typical Arctic outbreaks never came or only briefly visited places known for their frigid cold seasons.
As a consequence, the jet stream that pushes weather systems across the hemisphere flowed fast and straight from west to east — a situation that traditionally produces mild weather. (In February, the roaring jet stream enabled a plane to fly from New York to London in an unheard-of four hours and 56 minutes.)
It is not yet known whether this strong, persistent jet stream will become more commonplace as the world heats up, Haustein said. But winters that tend to be warm will become even warmer and sometimes wetter — taking a toll from ski slopes to farms, from bustling cities to windswept tundra landscapes.
This year’s strong Arctic Oscillation contributed to persistently warm, high-pressure air above the eastern United States. Winter storm tracks angled from the central United States toward Canada, missing much of the Appalachians and Mid-Atlantic, and the nor’easters that normally surge up the coastline were nowhere to be found.
“A third of the U.S. just wasn’t getting that deep, cold air,” said Karin Gleason, a climate scientist for the National Oceanic and Atmospheric Administration.
Yet the same phenomena that stole winter from the East Coast contributed to extreme cold in Alaska, heavy snowfalls in the Rockies and far northern New England and record-dry conditions in California.
“This pattern we’ve been in . . . means the folks that are getting snow are getting lots of snow and the folks that are getting rain are getting lots of rain and the folks that aren’t getting anything aren’t getting anything,” Gleason said.
For the National Weather Service’s Eastern Region, which extends from Maine to Georgia and along the Appalachians, average temperatures in January were seven degrees Fahrenheit above the 20th-century norm. The normally frozen Great Lakes spent much of the winter free of ice. Several cities notched record-low snowfalls this winter, and in February, Baltimore didn’t see a single flake.
In New Jersey, a state that has already warmed 3.6 degrees Fahrenheit from its preindustrial average, the season was among the warmest on record. Despite normal amounts of precipitation, snow accumulation for the winter was just 4.7 inches. The average annual snowfall for the state is 21 inches.
The above-freezing temperatures did mean that “potholes have not been a big menace,” said David Robinson, the state climatologist. “I guess that’s a silver lining.”
Across the Atlantic, warm air and a powerful jet stream combined to brew successive deadly storms over the United Kingdom. February was the wettest month in the country’s recorded history, according to the U.K. Met Office, and some regions received as much rain in a weekend as they normally would over 30 days.
Roiling brown rivers overtopped their banks, taking out bridges and deluging homes, even ripping off the tops of trees. At least six people were killed in the floodwaters, and roughly 2,700 properties suffered severe damage.
“It’s been a hideous winter,” tweeted John Curtin, executive director of flood and coastal risk management at the U.K. Environment Agency.
According to Haustein, climate change will make wet winters more frequent and severe in Britain. Sea level rise bolsters storm surge, making water more likely to breach coastal defenses. And warm air is able to hold more moisture, leading to heavier rainfall during storms.
To the northeast, Helsinki, Stockholm and Copenhagen were virtually snowless for the first two months of 2020, according to the Finnish Meteorological Institute’s Mika Rantanen. Satellite images showed much of Scandinavia remained bare brown and green in a season when it should have been blanketed in white.
This was also the first winter in history that German vineyards were unable to produce ice wine — a sweet specialty drink made from grapes that are allowed to freeze on the vine. Temperatures in December and January never dropped to the requisite 20 degrees Fahrenheit, winemaker Cornelius Dönnhoff said.
Ice wine from his family’s 250-year-old vineyard has received perfect scores from Robert Parker Wine Advocate, a famous wine rating system. But Dönnhoff has been unable to produce the delicacy since 2015, due to winters warmed by climate change.
“It’s basically a piece of culture that gets lost,” Dönnhoff said.
The balmy winter comes on the heels of a summer that was the hottest on record for the Northern Hemisphere. Fierce winds and ferocious heat fueled wildfires in Greece that killed more than 80 people. In Japan, deadly floods were followed by a killer heat wave. Germany in July notched its highest temperature ever recorded, 104.9 degrees Fahrenheit — and then broke that record the following day.
The land has “completely changed in one generation,” Dönnhoff said. “Every year we have to adapt to this new warm, hot weather we are having.”
In central Russia, days were so balmy they disrupted the hibernation of brown bears at the Bolsherechensky Zoo. Moscow officials had to cart in artificial snow for the city’s New Year’s festivities, and a suburban ski resort closed for part of December. On the resort’s website, owners posted a forlorn plea: “Winter, do you remember that you are winter?”
Reports from the Hydrometeorological Center of Russia became litanies of broken records: Temperatures in the Arctic region of Arkhangelsk were a staggering 14.4 degrees Fahrenheit above normal in December. The average winter temperature during December, January and February in Moscow was above freezing for the first time in recorded history. In January, a month the meteorological agency dubbed “the crown of winter,” temperatures for all but one federal district reached unprecedented highs.
Yulia Litvina, a 50-year-old Muscovite, said the dark days of the season have felt darker without the usual white covering of snow.
“I can’t remember anything like this,” she said. “You start to wonder if everything is correct in this world.”
The unseasonable weather is worrying to researchers who study the region’s permafrost — deep frozen soil that stores billions of tons of carbon. Warm winters can make it difficult for layers that thawed the previous summer to refreeze, according to University of Alaska geophysicist Vladimir Romanovsky, making the permafrost more vulnerable.
Roman Vilfand, director of the Russian Hydrometeorological Center, said at a February news conference that ‘the concept of ‘permanent’ disappears, and the frost turns out not to be eternal,” according to Reuters.
In California, a season that typically provides much of the state’s water for the year was desperately, disturbingly dry. San Francisco and Sacramento went the entire month of February without rain. The snowpack in the Sierras — which feeds the state’s rivers and supplies some of its drinking water — is less than half of what is normal for this time of year.
California emerged from a seven-year drought just last March and has endured several years of scorching summers that have killed crops and fueled wildfires. The state’s fire agency is already fighting two active incidents near Sacramento and Los Angeles.
This winter has also been much warmer than normal; dozens of weather stations across the state notched record highs.
“Growers are nervous,” said Don Cameron, general manager of Terranova Ranch, which grows vegetables, watermelon, pistachios and other produce southwest of Fresno. “We’ve seen our springs get warmer and our falls get warmer . . . and now winter.”
This year, for the first time in 39 years of farming, Cameron said, he had to irrigate his fields in February — a month that is typically foggy and cool.
As climate change makes California hotter and drier, Terranova Ranch has shifted its growing seasons for peppers, tomatoes and other crops. Cameron is talking to researchers about new, stress-tolerant varieties that will better withstand the state’s new weather extremes.
“There is so much change going on,” Cameron said. “We have to deal with it or we’ll be out of business.”
Andrew Freedman in Washington and Isabelle Khurshudyan in Moscow contributed to this report.