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Extreme weather makes climate change model “off-scale”

Fires, floods, heat waves, droughts. The deadly weather in recent weeks has “shocked” climate scientists and is concerned that extreme events will occur sooner than the model predicted.

In southern Oregon Fire in an area 25 times larger than Manhattan I was furious for weeks with the help of a record-breaking heat wave.In China, floods kill 51 people in a year’s worth of floods It rained in a day in the central city of Zhengzhou Caused over $ 10 billion in damage.

And in Russia, a state of emergency was declared in Yakut, the Far East, where the authorities are. Make artificial rain By sowing silver iodide in the clouds in an attempt to extinguish more than 200 fires.

Climate scientists say that even when global warming is fully considered, the severity of these events is simply “off-scale” compared to what atmospheric models predict.

Chris Rapley, a professor of climate science at University College London, said: “There are dramatic changes in extreme frequency [weather] The event will occur. ”

From Deadly flood in Germany last weekThe pace and magnitude of the devastating damage to Canada’s heat wave and floods in the Black Sea region was almost unimaginable, even for experts who spent their lives studying it.

A wildfire in the Republic of Sakha, also known as Yakutsk in Russia. The governor of the region has made it clear that global climate change is the cause. © AP

One factor behind many of these events is the changing pattern of jet streams, the fast-flowing bands of air that dominate the weather in the Northern Hemisphere. Especially during the summer, it slowly undulates.

Slow and wobbling jet streams increase the size of high-pressure and low-pressure systems and keep them in place, explains Michael Mann, director of the Center for Earth Systems Science at Pennsylvania State University.

This means that both heat waves and droughts (linked to high pressure systems) and floods (linked to low pressure systems) will be more persistent.

The phenomenon known as “planetary wave resonance” is behind recent times. heat wave For example, in North America, temperatures in Western Canada reached 49 degrees Celsius.

Also in the heat of the Russian Arctic, where large wildfires produce toxic smoke and cover Yakutsk, the port city of Siberia, well known as one of the coldest winter cities on the planet. Contributed. The fire caused one of the worst air pollution events in the world, producing dangerous levels of particulate matter.

A diagram showing how jet streams affect the weather. Strong jet stream: Large pressure differences help keep the jet stream in a straighter path, including cold air above the Arctic. Weak Jet Stream: The weaker the jet stream, the more wavy it is — the cold air above the North Pole descends south and the warm air is pushed north.

Mann is worried that the current model does not accurately reproduce the behavior of the jet stream. “This means they underestimate the magnitude of climate change’s impact on extreme weather events,” he says.

“Global warming is in close agreement with climate model projections decades ago, but extreme weather events are higher than expected,” Mann said.

The world has warmed by an average of about 1.2 ° C since before the Industrial Revolution, but the warming is unevenly distributed, and the Arctic Circle is mainly due to the loss of reflected snow and ice in other parts of the world. It is warming about three times faster.

This Arctic heating has a significant impact on the jet stream. The jet stream is partially dominated by the temperature difference between cold polar air and warm tropical air.

In Germany and Belgium, slow jet streams were one of the causes of this month’s floods, killing more than 120 people and destroying towns and villages.

“We had a cyclone in Central Europe and it didn’t move. It was persistent and long lasting. Normally, our weather patterns moved from west to east,” said the Potsdam Institute for Climate Impact Research. Researcher Fred Hatterman said.

Erftstadt, Germany-A damaged castle in Blessem. The flood killed at least 170 people. © Michael Probst / AP

“Our westerly engine is the temperature gradient from the equator to the Arctic,” he explains. Warming in the Arctic means “weakening this engine we have.

Not all extreme weather events are related solely to jet streams.

Global warming also has a direct impact on precipitation and rainfall, as warm air can retain more water. 7% more water for every 1C warming.

This is part of the reason why recent floods in India and China are so devastating that they involve a monsoon cycle rather than jet stream behavior.

In the heavy rain that hit Henan Province in central China last week, a 20 cm waterfall was seen in the capital Zhengzhou in an hour. Extensive floods that hit the subway drowned 12 passengers.

Rescue workers help people cross the flooded streets of Zhengzhou © AFP via Getty Images

By Friday, the floods had killed 51 people and caused direct damage worth RMB 65.5 billion ($ 10 billion) in Zhengzhou alone. According to the China Meteorological Administration, an unusually large amount of water vapor was pushed inland by a typhoon on the southern coast of South China, sprayed into the mountains of Henan Province, and then rained.

Consistent high pressures in the Sea of ​​Japan and northwestern China mean that rain clouds stagnate in a cyclone vortex over Hennan, resulting in a series of slow-moving, violent, continuous storms known as the “train effects.” The government told the Chinese that it did.

Chinese officials said the amount exceeded the record for the past 5,000 years and was extended to the official start date of the Chinese civilization.

Meanwhile, in northeastern Russia, firefighting teams continue to fight more than 200 flames. The Yakut region regularly experiences lows of -50 degrees Celsius in several places, but recently set some new records for highs in the Arctic.

Governor, 49-year-old Eisen Nikolaev, I was alerting for a long time About the effects of global warming in his area.

“There is definitely one reason, it’s global climate change,” he told local television. “It’s happening, we see Yakut getting hot every year.”

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Extreme weather makes climate change model “off-scale”

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