Jet stream buckles as heat increases, causing more heatwaves
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Boston — The heat rolled in, the lights went out, a fire tornado materialised in the sky and the hottest temperature anywhere in the world since 1931 was recorded in Death Valley.
It was a California weekend for the history books, adding to 2020’s global tally of extremes — including fires, heatwaves and tropical storms. This year has arguably offered a glimpse into the future of our climate-changed world.
But as far as the Golden State is concerned, that future may be here — now.
“These are things we have in the projections for mid-century, not 2020,” said Nik Steinberg, head of research at Moody’s Four Twenty Seven, an analytics company that provides climate-risk assessments for business and government. “They are becoming part of the norm and happening much quicker than anticipated.”
The first seven months of 2020 were the second warmest on record going back some 141 years, according to the US National Centres for Environmental Information. In April, Florida baked under summer-like temperatures; Siberia has been setting heat records all summer; and the US southwest has sweltered under a high pressure system that’s kept the region’s annual monsoon at bay.
It’s this large heat dome — stuck like a big rock in a stream — that’s allowed temperatures to break records across California. A resulting energy spike tied to air conditioning triggered the subsequent blackouts that have left millions without power.
It used to be that these heat domes would move on after a few days. But as the world warms, they can sometimes become stuck. And the longer they stay stuck, the more destructive they can become. These weather patterns are likely to be more common as the jet stream, the river of air that circles the globe, becomes weaker.
Why is it weakening? The difference between summer temperatures at the equator and the North Pole is shrinking, causing the jet stream to lose some of its power. That can lead to buckles in its flow that make it harder for cooler, lower pressure systems to muscle their way in and bring relief. In recent years, people trapped beneath high pressure systems have faced elongated heatwaves, while those under low pressure systems have seen persistently mild temperatures and rain.
The current high over California was pinned there by such a buckle, said Jennifer Francis, a senior scientist at Woodwell Climate Research Centre in Massachusetts.
“We can’t say ...
It was a California weekend for the history books, adding to 2020’s global tally of extremes — including fires, heatwaves and tropical storms. This year has arguably offered a glimpse into the future of our climate-changed world.
But as far as the Golden State is concerned, that future may be here — now.
“These are things we have in the projections for mid-century, not 2020,” said Nik Steinberg, head of research at Moody’s Four Twenty Seven, an analytics company that provides climate-risk assessments for business and government. “They are becoming part of the norm and happening much quicker than anticipated.”
The first seven months of 2020 were the second warmest on record going back some 141 years, according to the US National Centres for Environmental Information. In April, Florida baked under summer-like temperatures; Siberia has been setting heat records all summer; and the US southwest has sweltered under a high pressure system that’s kept the region’s annual monsoon at bay.
It’s this large heat dome — stuck like a big rock in a stream — that’s allowed temperatures to break records across California. A resulting energy spike tied to air conditioning triggered the subsequent blackouts that have left millions without power.
It used to be that these heat domes would move on after a few days. But as the world warms, they can sometimes become stuck. And the longer they stay stuck, the more destructive they can become. These weather patterns are likely to be more common as the jet stream, the river of air that circles the globe, becomes weaker.
Why is it weakening? The difference between summer temperatures at the equator and the North Pole is shrinking, causing the jet stream to lose some of its power. That can lead to buckles in its flow that make it harder for cooler, lower pressure systems to muscle their way in and bring relief. In recent years, people trapped beneath high pressure systems have faced elongated heatwaves, while those under low pressure systems have seen persistently mild temperatures and rain.
The current high over California was pinned there by such a buckle, said Jennifer Francis, a senior scientist at Woodwell Climate Research Centre in Massachusetts.
“We can’t say ...
