How record February heat is priming the US for crop-wrecking ‘whiplash’

How record February heat is priming the US for crop-wrecking ‘whiplash’

Forget spring: This week, much of the interior U.S. is getting a sneak preview of summer.

A wave of unusual high temperatures — often 30 to 40 degrees above average — are blasting states from Texas to the Dakotas and east to the shores of the Great Lakes.

That heat follows the hottest December on record, and may push February into first place as well — a dynamic that is a harbinger of a hotter summer to come, and that is pushing several heartlands of American agriculture into a newly precarious state.

Much of America “had a two-week winter,” said Brad Rippey, a meteorologist with the U.S. Department of Agriculture. Across the country, trees are budding, and crops such as oats and winter wheat are sprouting above the soil two weeks early — putting them at risk if unseasonal heat yields to killing cold, as it did in the disastrous springs of 2007 and 2017.

Spring has arrived up to two weeks early this year compared to the 20 year average, according to the National Phenology Network, from five days early in Portland, Ore. to 13 days in Virginia Beach, Va.

That’s not to say the whole continent is warm, or even that the phenomenon of a late February warm front is unusual.

It’s normal for cold temperatures in the northwest this time of year to draw a mass of hot air up through the center of the country, said Joe Wegman, a meteorologist at National Oceanic and Atmospheric Administration (NOAA) Weather Prediction Center.

And cold temperatures across Canada, Alaska and the Pacific Northwest are “terribly widespread,” said Judah Cohen, who runs the seasonal forecasting practice at Verisk AER, which does does predictions for federal agencies such as NOAA and NASA.

There’s also the fact that the Pacific Ocean is in its El Niño pattern — driving warm Pacific air across the interior U.S., as opposed to the frigid Arctic air that dominates during the La Niña, Scott Handel and Anthony Artusa of NOAA’s long-term Climate Prediction Center told The HIll.

But as planetary heating stacks on top of natural fluctuations in weather, “the warm parts aren’t just a little above normal,” Cohen said. “They can easily reach record warmth, because there’s just so much warmth in the system.”

This leads to a risk of “weather whiplash,” Cohen said, in which weather becomes “like a windshield wiper: ping-ponging back and forth from one extreme to the other.”

Right now, that pingpong ball is on the hot end of the table. Federal meteorologists expect more than 70 daily records to be broken Tuesday. The looming heat is remarkable in many places both for how much temperatures will be than previous records — often as much as 5-10 degrees above previous anomalous heat waves — and for how long many of the soon-to-fall records have stood.

In eastern Nebraska, for example, NOAA expects Tuesday temperatures that will shatter by 6 degrees the previous February record — a standard set in 1826, almost two centuries ago.

That case is a bit of an outlier, said NOAA’s Wegman. Mostly, he said, records are falling “by 1-2 degrees, but we’re seeing records in place for 100-plus years being broken.”

In Texas, that looks like highs in the lower 90s — about 30 degrees above normal. In Iowa and eastern Nebraska, where the anomaly is most pronounced (and average seasonal temperatures far lower), it means high temperatures up to 40 degrees above average.

Many of the states being hit by unusual warmth are in the heartlands of key U.S. crops, from blueberries and peaches to oats and wheat.

For most of these regions, early heat “shouldn’t be a big deal,” the Agriculture Department’s Rippey told The Hill. While he said it’s “not ideal” — many crops are adapted to a particular mix of heat and steadily increasing hours of daylight that this heat anomaly may throw off — as long as temperatures remain above normal, it should just mean an early harvest.

But an early leaf-out for fruit trees and early sprouting for row crops including oats, corn, soy and wheat also mean that those plants are uniquely vulnerable to another kind of anomaly: a late-spring freeze that kills young plants that in normal years would still be safely nestled in the ground, or freezes the leaves off of orchards that would normally still be dormant.

The worst example of this was the early April freeze of 2007, which followed a record warm March. That spring, sub-20 degree temperatures and high winds devastated vulnerable seeds, trees and saplings — leading to an economic disaster that won the grim honor of a spot on NOAA’s billion dollar disaster list, a first-ever distinction for a spring freeze. A similar disaster happened in 2017, when a mid-March freeze followed an unusually warm February.

While it’s impossible to make any predictions more than two weeks out, the risk of this kind of “weather whiplash” is increasing, Cohen said.

That’s due to a complex combination: warmer oceans — an increasingly charged thermal battery, which now dumps higher levels of heat back into the atmosphere in the cold months; and a weakening polar vortex, which allows arctic cold to escape.

This week’s records demonstrate the first part of that system: Normal late-winter seasonal patterns of warming “are going straight to record warmth.” Because there’s so much more heat in the air and sea in general, “you are starting from a higher rung on the ladder — to reach the top is just easier,” Cohen said.

He added that while “some people consider what I just said controversial, it’s the least controversial thing I’ve ever said in my life.”

Less intuitive is the relationship between rising global temperatures and outbreaks of March cold. Cohen explains the risk of late-season freeze with the image of a two figure skaters spinning with clasped arms in tight circles on the ice — an analogy for the high-velocity winds of the polar vortex that keep the Arctic cold situated above the North Pole.

But more heat in the southern ocean is creating a windier jet stream, which “is like one of those figure skaters hitting a crack in the ice.” As the skater stumbles, their arms flail out behind them, “and it’s the same thing with the polar vortex — as they are hit by the energy coming from the jet stream down below, their circulation slows down, and you get more outbreaks.”

In effect, this blurs the once-clean distinction between a frigid north and a mild south — a dynamic that Cohen described in a 2021 The Hill op-ed.

For crops, he added, “the risk is a freeze: They have this ‘false spring’ when things unusually warm, things start to bloom — then they get below-freezing temperatures, and the crop is damaged.”

That’s a particular concern for the blueberries and peaches of the Southeast, as well as “vulnerable” oats and winter wheat, he said.

The unusual temperatures also risk worsening drought. As part of photosynthesis, plants break down water from the soil to build the starches and sugars that form their bodies — and, ultimately, our food.

As crops use soil moisture “more and earlier,” that leads to risk of crops being depleted — particularly in the key corn and soy regions of the upper Midwest, where a “snow drought” has led to below-average levels of water seeping into the soil, Rippey said. As plants struggle upward in an already depleted region, those areas “could run out of moisture if we don’t get adequate rainfall,” he added.

This year’s weather offers one serious consolation over previous ones: The drought that gripped much of the U.S. has largely receded, and a water-stressed part of the Midwest is one of just a few significant pockets where it lingers. Just more than a quarter of the U.S. corn- and soy-growing regions are in drought right now, with only 12 percent of winter wheat in drought.

But that good news only holds as long as the moisture does, and it can be deceptive. Last winter, wet weather prompted many West Texas cotton farmers to believe it was going to be a wet year — an assumption that was cruelly broken, Robbie Minnich of the National Cotton Council told The Hill.

“They thought, you know, all right, ‘The drought has broken, it’s turned around,’ and so they really put everything into it,” Minnich said. “And then they got into June, and it stopped raining and it was 120 degrees.”

Does the record February heat mean a hot summer to come?

Looking at the broader trends, Handel and Artusa of the Climate Prediction Center favor an “above normal for most of the country for the summer as a whole.”

That’s the result of a complex mix of factors, most notably the likely transition for El Niño back to La Niña, which on average has meant hotter summers across the continental U.S.

But as far as just how anomalous that heat will be, NOAA scientists say it’s far to early to say.

“You can see a based on larger planetary patterns that there a given month — or even multi-month — period will be warmer than normal,” Wegman of the Weather Prediction Center said.

“But to say that this will mean that the entire summer is 30 degrees above normal? That’s beyond the realm of the science at the moment.”

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