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Climate change ‘supercharges’ tropical cyclones like Ida

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As I write this on the evening of Saturday, August 28, Hurricane Ida is hitting the Louisiana coast just south of New Orleans. Bursting with unusually warm waters, it is expected to strengthen into a monster Category 4 hurricane before making landfall on Sunday.

Regardless of where its last landing will be, the National Hurricane Center has said the impact of storm surges, high winds and flooding will be catastrophic.

According to NOAA, a Category 4 hurricane will cause catastrophic damage: “Well-constructed frame homes can suffer serious damage with the loss of most of the roof structure and / or some exterior walls. Most trees will be broken or uprooted and utility poles cut down. trees and utility poles will isolate residential areas. Power outages will last for weeks or even months. Most of the area will be uninhabitable for weeks or months. (Credit: NOAA National Hurricane Center)

Storms like this make many of us question the influence of man-made climate change. So here are some quick excerpts from the Intergovernmental Panel on Climate Change. report, as well as recent scientific studies.

Main tropical cyclones

Scientists still cannot tell if the frequency of all tropical cyclones is increasing. And data going back to 1900 shows no trend in the frequency of landing events in the United States.

But the IPCC report says it is likely that the proportion of large tropical cyclones like Ida has increased globally over the past four decades. (On the Saffir-Simpson hurricane wind scale, “major” means Category 3 to 5 hurricanes.) In addition, attribution to human influence has increased in recent years.

Damage

Since 1900, the United States has experienced an increase in standardized damage from hurricanes, according to the IPCC. “Normalized” means that researchers have adapted to societal changes – particularly increased development along the coasts – that have occurred over time.

For example, a to study published last year in the Proceedings of the National Academy of Sciences found a positive trend in normalized damage, with the rate of major damage events increasing significantly. The researchers attribute this to “a detectable change in extreme storms due to global warming.”

Between 2020 and 2021, the United States suffered 258 weather disasters, with hurricanes causing the most damage, according to NOAA. The total of these storms: $ 945.9 billion, with an average cost of nearly $ 21.5 billion per storm. Hurricanes are also responsible for the largest number of deaths in the United States from weather disasters: 6,593 people were killed between 1980 and 2020.

Hurricane Katrina, which somehow resuscitated Ida, caused $ 125 billion in damage. That was an incredible 1% of gross domestic product for the entire United States in 2005.

Water and wind

Monster storms cause enormous damage not only because of their winds. They also spill unimaginable amounts of water. And research shows that thanks to climate change, they have become wetter.

This happens for a number of reasons. First, a warmer atmosphere can carry more moisture. Research shows that for every one degree Celsius (1.8 degrees Fahrenheit) increase in temperature, the atmosphere can contain 7 percent more humidity. So far, the globe has warmed by around 1.1 ° C since pre-industrial times.

A more humid atmosphere is not the only factor that makes tropical cyclones more humid. Warming seas is another. In fact, rising temperatures invigorate storms in a number of ways.

Just before the northern summer of 2017, the heat content of the oceans was the highest on record, “supercharging Atlantic hurricanes Harvey, Irma and Maria,” according to a study led by Kevin Trenberth of the National Center for Atmospheric Research. Overall, he and his colleagues concluded that increasing ocean heat, along with warmer sea surface temperatures, make hurricanes “more intense, bigger and longer lasting and greatly increase their rainfall. flood “.

A major caveat

If we are to stabilize the climate before much worse impacts occur, it is imperative that we take strong, swift and sustained action to reduce greenhouse gas emissions. But even if we do this, “some of the changes already underway – such as continued sea level rise – are irreversible over hundreds or even thousands of years,” the IPCC said in A declaration. In addition, the greenhouse gases that we have already pumped into the atmosphere will continue to modify the climate for decades to come.

The inevitability of future climate change makes this point particularly important:

As storms will continue to intensify as the world warms, we can mitigate future damage by changing where and how we build in areas affected by tropical cyclones.


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