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Analysis: Ida makes New York a weather frontline supercharged by climate change

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The New York authorities seemed totally caught off guard by the floods. Meteorologists – who knew storms and floods were on their way, even roughly how much rain would fall – were surprised by the tempo of the storm.

“It’s dangerous. We are seeing some kind of rain – we hardly ever see that kind of speed with which the rain has come,” New York Mayor Bill de Blasio said, urging everyone to stay. at home.

New York Governor Kathy Hochul said she couldn’t guarantee responders could rescue people who might be stuck in their car “if it starts to float like a boat on a river.”

Eight people have already died in New York and New Jersey, both in states of emergency.

“What is so surprising is the duration of the precipitation and the area affected,” said Michael Guy of CNN Weather.

“It’s such a large area in the northeast, and it only happened in a matter of hours. It’s nothing we’ve seen, especially in this part of the country.”

As with several weather events during the summer in the northern hemisphere, Ida broke records in some areas by a huge margin.

Central Park in New York, for example, recorded 7.13 inches of rain on Wednesday, nearly doubling the previous record of 3.84 inches, set in 1927, the National Weather Service New York reported. In Newark, New Jersey, it was 8.41 inches, nearly four times the previous record of 2.22 inches in 1959.

New York City’s flash flood emergency status is the first in its history.

What is the role of climate change?

Globally, extreme precipitation – including that in Germany and China in recent months – is increasingly common due to man-made global warming, scientists say.

A recent UN climate report stated that “the frequency and intensity of heavy rainfall events have increased since the 1950s over most of the land area”.

Across the continental United States, in particular, the heaviest showers were seen increasing in all regions, with the northeast showing the largest increase, according to the United States National Climate Assessment.

“Warmer air may contain more water vapor than colder air. Global analyzes show that the amount of water vapor in the atmosphere has actually increased both on land and in the oceans. “, says the report.

When it comes to hurricanes, climate change makes them more dangerous. They produce more precipitation, move slower once they make landfall, and generate larger storm surges along the coast. Hurricane Ida was a prime example of these changes, and scientists say storms like this will become more frequent as the planet warms.

Scientists are now able to analyze exactly what role climate change is likely to have played in a particular weather event. It’s too early to make such an estimate for Ida, but hurricane trends of this force suggest a link.

Storm Ida caused flooding in the Ditmas Park neighborhood of Brooklyn, New York on Wednesday.

“What we can say, without doing a dedicated attribution study, is that the major hurricanes (categories 3-5) have increased over the past few decades, which cannot be explained by natural variability alone.” , Friederike Otto, who co-leads the World Weather Attribution initiative, said CNN in an email.

“Specifically, from the attribution of the events, we note that when hurricanes do occur, the rainfall associated with them is more intense due to human-induced climate change, and Ida will be no exception.”

While there is less certainty about the impacts of climate change on wind speed and some other factors, there is great confidence that the speed of translation – how fast the entire system is moving – of hurricanes slowed down, Otto said.

“This is important because it means that cyclones stay longer and can therefore also cause more damage.”

CNN’s Brandon Miller and Rachel Ramirez contributed to this report.


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