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There are records—like Wednesday being the earliest 80-degree day in Washington, D.C., history—and then there are the eye-popping effects of those records, like seeing people wearing T-shirts on the streets of Portland, Maine, in February.
However you measure it, Feb. 20-21, 2018, were days for the books—days when the records fell as quickly as the thermometer rose, days that gave a glimpse into the wacky weather that the new era of climate change brings.
“What we have is a large-scale pattern that wouldn’t be too uncommon in the spring,” said meteorologist Patrick Burke of the National Weather Service. “But it’s a little bit unusual to see it set up this way in February—and set up with such persistence.”
Central Park hit 76°F. Boston had back-to-back 70°F days. Towns in Virginia and Vermont were pushing 80°F, with some Vermont towns warning residents that rapid snowmelt from the heat could cause a new round of flooding. In Pittsburgh, a high of 78°F beat a record set in 1891 by a whopping 10 degrees.
The warm temperatures do feel strange this time of year, but it’s easy to forget that this isn’t the only abnormally hot February in recent years. February 2017 saw extraordinary temperatures, too. February 2016? Same thing.
It’s been happening with greater frequency—and in line with what scientists have said to expect as the world warms.
The Warming Comes with Risks
“It used to be said that ‘scientists can’t say anything about an individual event.’ That statement is patently false now,” said Michael Wehner, a senior staff scientist at Lawrence Berkeley National Laboratory. “We can say lots about individual events, and we have.”
“Climate change is not a future problem. It’s a present-day problem,” he said.
Wehner and his colleagues specialize in determining what role climate change may have played in extreme weather and heat events.
“Typically, it’s the heat waves in summer that have all sorts of negative impacts,” Wehner said. “A heat wave in winter is just a nice day. But there can be impacts that we need to deal with.”
The snowpack in the Sierra Nevada, for instance, which is the water source for about a third of California, is near historic lows.
Alongside the temperature data, scientists watch indicators like the Spring Leaf Index, which tracks how early leaves are returning compared to normal timing. And it’s possible, using the same methods, to let farmers and foresters know about planting times—and the arrival of pests.
The Arctic’s on a Hot Streak
As temperature records were falling up and down the East Coast, the Arctic continued on a hot streak, with the far-reaches of Alaska’s North Slope seeing temperatures 45°F above normal.
A weather station at the northern tip of Greenland showed temperatures above freezing for much of Feb. 20.
Extreme Rainfall and Flooding
Meanwhile, a different kind of record was being set in the middle of the country.
The same unusual weather system that’s bringing warm temperatures is also bringing record-high amounts of precipitation into the atmosphere, dumping rain from Texas to the Great Lakes, Burke said. This type of storm system might normally result in 2 or 3 inches of rain. But the high-pressure ridge along the East Coast is ensuring that the storm just sits there, making it more likely to bringing 5 or 7 inches, and even more in some places.
“That will overwhelm some of the river systems, particularly where the ground is cold, like the Ohio Valley and lower Great Lakes,” Burke said. “Add the water on top of ground that was frozen or that had recent snow melt, and you’ll have flooding that’s even worse.”
South Bend, Indiana, broke precipitation records this week, and the city and surrounding region along the Michigan-Indiana border were facing widespread flooding as rivers continued to rise. South Bend Mayor Pete Buttigieg said his city was facing a 500-year flood event. On top of melting snow, the rainfall has raised some rivers to record levels in the region, and the National Weather Service warned that flooding would continue through the week, with more precipitation possible.