A high of 34 degrees in Boston today, while D.C. sees highs in the mid-70s. What’s with the huge difference? – The Boston Globe
Boston is getting pummeled with snow and wind on Thursday. But 400 miles south, the Washington, D.C., and Baltimore area is enjoying a balmy day, with temperatures expected to climb into the mid-70s.
The wide disparity is a pattern some climate scientists say we’ll see more as climate change progresses.
The climate crisis isn’t just making weather warmer overall, it’s also making it more variable. Experts say it could have been a factor, for instance, in New England’s swift oscillation this month from a cold snap to spring-like temperatures less than two weeks later.
“When you say global warming, everybody expects us to be warmer all the time, but what’s really happening is that our weather patterns are being disrupted overall and we’re seeing more variability,” renowned atmospheric scientist Katharine Hayhoe told the Globe in early February. “That’s why I often refer to what we’re seeing as ‘global weirding.’”
That variability is increasing not only over time in individual places, but also over geographical locations at the same time.
“This is also global weirding,” said Hayhoe on Thursday.
It’s normal, of course, for the D.C. area to be 5 or 10 degrees warmer than Boston — while the average high and low for February in Boston from 1991 to 2020 was 39.4 degrees and 24.8 degrees, respectively, in D.C. those numbers were 47.8 and 31.4. But today, the temperature difference between the two areas could reach 40 degrees.
Currently, different parts of the United States are facing weather extremes. Swaths of the West could break daily cold records, with a stunning blizzard warning in place for Los Angeles — yes, really. Meanwhile, Thursday will feel “more like June than February” in the Ohio Valley and Mid-Atlantic as temperatures climb to more than 40 degrees above average, according to the Weather Prediction Center.
The reason for today’s wild weather is the jet stream, a band of east-west winds around the globe that influence global weather.
“The jet stream pattern today tells the whole story,” said Jennifer Francis, senior scientist at the Woodwell Climate Research Center in Woods Hole.
Right now, there is an unusually deep southward dip in the jetstream over the US West, and it has brought cold, Arctic air to the region. Meanwhile, strong winds reaching from Baja to New England are bringing high temperatures to the south and east, Francis explained.
Another major dip in the Jet stream over North America. We may even see snow in Southern California. The wacky weather continues as the rolling Rossby’s circle the globe. Modern agriculture wasn’t built on weird weather patterns. pic.twitter.com/QGQ2o4yD8N
— Peter Dynes (@PGDynes) February 22, 2023
The jet stream forms between cold air in the north and warm air in the south. When air of two different temperatures meets, the warm air rises while the cool air sinks, creating strong, straight winds. But because the Arctic has warmed so quickly — nearly four times faster than the rest of the world over the past 43 years, studies show — the difference between temperatures there and those in mid latitudes is decreasing. As a result, there’s evidence that the jet stream is getting wavier and more meandering.
“When huge waves like this form in the jet stream, we always see crazy weather, and often extremes of opposite flavors exist side-by-side, as is the case today,” said Francis.
Other factors that could be contributing to the jet stream’s current waviness: strong, long heatwaves happening in the North Pacific and eastern seaboard, and La Nina, which refers to strong winds blowing warm water on the surface of the Pacific Ocean from South America to Indonesia.
How much of a factor is climate change in these changes in the jet stream? Scientists are still hotly debating that issue.
“That’s a really active area of research,” said Kristy Dahl, principal climate scientist at Union of Concerned Scientists, a Cambridge-based nonprofit focused on science advocacy. “I wouldn’t say scientists have settled it.”
But evidence is mounting that these wilder bends and kinks are occurring more frequently, said Francis. So as the planet warms, we could see this trend become more frequent and more extreme.
The good news is that there is an opportunity to limit future extreme weather by curbing planet-warming emissions. And governments and communities can take steps to adapt to the changes that are already occurring.
To do so, said Hayhoe, we need to internalize that signs of climate change are all around us, said Hayhoe.
“It’s not about the future. It’s not about what’s happening way over elsewhere,” she said. “It’s about what’s happening right here where we live.”
Dharna Noor can be reached at firstname.lastname@example.org. Follow her on Twitter @dharnanoor.