Extreme weather makes climate change models “out of scale”


Fires, floods, heat waves and droughts. The deadly weather in recent weeks has “shocked” climate scientists and fears that extreme events are coming even faster than models predicted.

In southern Oregon, The fire area is 25 times that of Manhattan With the help of a record-breaking heat wave, it has been raging for several weeks.In China, the flood killed 51 people a year later Single day rainfall in Zhengzhou city center Caused losses of more than 10 billion U.S. dollars.

In Russia, Yakutia in the Far East has declared a state of emergency, and the authorities are there Create artificial rainfall By spreading clouds with silver iodine, it tried to extinguish more than 200 fires.

Climate scientists say that the severity of these events is only “out of scale” compared to the results predicted by the atmospheric model—even when global warming is fully taken into account.

Chris Rapley, professor of climate science at University College London, said: “I think I’ll say on behalf of many climate scientists that we are a bit shocked by what we see.” “The frequency of extreme events has changed dramatically. [weather] The incident happened. ”

From Deadly floods in Germany last week, Canada’s scorching heat and the floods in the Black Sea region, the speed and scale of catastrophic damage are almost unimaginable, even for experts who have studied it all their lives.

A driving factor behind many of these events is the changing pattern of jet streams, a fast-moving band of air that controls weather in the northern hemisphere. It becomes slower and fluctuates, especially in summer.

Zhengzhou is the location of the world’s largest iPhone assembly plant. The heavy rain in the central Chinese city of Zhengzhou was described by the local meteorological department as more than any recorded event. © AFP via Getty Images

Michael Mann, director of the Earth System Science Center at Penn State University, explained that when the rapids become slow and unstable, the number of high-pressure and low-pressure systems will increase and get stuck in place.

This means that heat waves and droughts (related to high-pressure systems) and floods (related to low-pressure systems) have become more persistent.

This phenomenon called “planetary wave resonance” is recent Heat wave For example, in North America, the temperature in western Canada is as high as 49 degrees Celsius.

It also causes extreme heat in the Russian Arctic, where widespread wildfires are producing toxic smoke, covering the Siberian port city of Yakutsk, which is better known as one of the coldest winter cities on the planet. The fire caused one of the most serious air pollution incidents in the world, producing dangerous levels of particulate matter.

Graphic showing how the rapids affect the weather. Strong jet stream: The huge pressure difference helps to keep the jet stream in a straighter path and contains cold air over the North Pole. Weak jet stream: When the jet stream weakens, it becomes more wavy—allowing the cold air above the North Pole to descend southward, while the warmer air advances northward.

Mann is concerned that the current model cannot accurately reproduce the behavior of the jet. “This means they underestimated the impact of climate change on extreme weather events,” he said.

“Although the overall warming of the earth is basically the same as predicted by climate models decades ago, the increase in extreme weather events has exceeded the forecast,” Mann pointed out.

Since the pre-industrial era, the world’s average temperature rise is about 1.2 degrees Celsius, but this temperature rise is unevenly distributed. The Arctic region’s temperature rise rate is about three times that of the rest of the world, mainly due to the disappearance of reflective ice and snow.

This Arctic heating has a significant effect on jet streams, partly because of the temperature difference between the cold polar air and the warm tropical air.

In Germany and Belgium, slower rapids were a factor in the flooding this month, killing more than 120 people and destroying towns and villages.

“We have a field of low pressure over Central Europe. It does not move. It is persistent and persistent. Usually our weather patterns move from west to east,” said Fred Hartman, a researcher at the Potsdam Institute for Climate Impact Research.

A damaged castle in Erftstadt-Blessem, Germany. Floods caused at least 170 deaths. © Michael Probst/Associated Press

“Our west wind engine is a temperature gradient from the equator to the North Pole,” he explained. The warming of the Arctic means “the engine we have is weakened.

Not all extreme weather events are only related to rapids.

Global warming also has a direct impact on precipitation and rainfall, because warmer air can hold more moisture-approximately For every 1 degree Celsius increase in temperature, the amount of water will increase by 7%.

This is part of the reason why the recent floods in India and China are so destructive, involving monsoon cycles rather than surges.

In the heavy rain that swept through Henan Province in central China last week, Zhengzhou, the capital of the province, dropped 20 centimeters of water in one hour. The massive flood that flooded its subway drowned 12 passengers.

As of Friday, floods in Zhengzhou alone had caused 51 deaths and 65.5 billion yuan (US$10 billion) in direct losses. According to the China Meteorological Administration, an unusually large amount of water vapor was pushed inland by a typhoon on the southern coast of China and turned into rain after blowing over the mountains in Henan.

The continued high pressure in the Sea of ​​Japan and northwestern China meant that rain clouds stagnated in a low-pressure vortex over Henan, becoming a series of slow-moving intense and continuous storms, known as “train influence”, the government told the Chinese national media.

The Chinese authorities stated that the number exceeded any record in the past 5,000 years and continued until the official start date of Chinese civilization.

Forest fires in the Sakha Republic (also known as Yakutia, Russia). The governor of the region knows that global climate change is to blame. © Associated Press

At the same time, in northeastern Russia, the fire brigade continued to extinguish more than 200 fires. Low temperatures of minus 50 degrees Celsius are often seen in some parts of Yakutia, but several new records for the highest temperature in the Arctic Circle have recently been set.

49-year-old governor Aysen Nikolayev (Aysen Nikolayev) Has been sounding the alarm for a long time The impact of global warming on his region.

“There is no doubt that there is only one reason-global climate change,” he told the local TV station. “It is happening and we see Yakutia getting hotter every year.”

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