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Climate change makes hurricanes stronger

Hurricane Ian is rapidly strengthening in the Caribbean as it passes through the extremely warm waters of the Caribbean and the Gulf of Mexico. The National Hurricane Center has predicted the system will rapidly strengthen from a tropical storm to at least a Category 4 hurricane in less than 72 hours.

It is a unprecedented forecastExperts told CNN, but one scientist says it’s more likely to happen as the climate crisis progresses, pushing ocean temperatures higher and setting the stage for tropical cyclones to explode. at breakneck speed into massive deadly storms.

Rapid intensity is exactly what it sounds like – the winds of a hurricane strengthen rapidly over a short period of time. Scientists have defined it as a wind speed increase of at least 35 mph in 24 hours or less.

The phenomenon unfolded at breathtaking speed in the Philippines this weekend. Super Typhoon Noru bursts into strength on final approach to the Pacific island nation, going from the equivalent of a Category 1 hurricane to category 5 overnight when residents around Manila were asleep.

Noru’s rapid strengthening just before landfall – which was not anticipated – may mean that locals don’t have time to prepare for a much stronger storm.

Hurricane Ian has been forecast for several days, providing the benefit of time for Cuba and Florida. Winds during the storm increased from 45 mph on Sunday night to 80 mph late Monday morning and are forecast to be stronger. Ian could strengthen at least to Category 4 before it makes landfall in Florida midweek.

According to Allison Wing, assistant professor of atmospheric science at Florida State University, historically rapid intensification is a rare phenomenon.

“It’s really the tipping point of how quickly hurricanes can strengthen,” Wing told CNN. “Only about 6% or so of all forecast periods have these types of rapid enhancement rates observed associated with them. And by definition, that’s a rare event. Sometimes it only happens a few times per season.”


Live updates: Florida prepares for Hurricane Ian

But human-caused climate change is tilting the decks toward more intense storms. So they’re not only generating more rain and stronger high tides – they’re also more likely to be stronger and intensifying faster.

“Climate change is increasing both the maximum intensity that these storms can reach and the rate at which intensification can bring them up,” said Jim Kossin, a senior scientist at the Climate Agency. Maximum levels”. “The intensification rates in Noru and Ian are prime examples of very rapid intensification, and there have been many more recently.”

Kossin told CNN that the two ingredients must work together to enhance rapidly. The first is that the upper winds around the storm need to be weak – strong winds can prevent a storm from strengthening or even tear it apart.

The second is that warm ocean water must expand below the surface, hundreds of feet deep, to provide enough fuel for the storm to strengthen.

According to the National Oceanic and Atmospheric Administration, more than 90% of global warming over the past 50 years has occurred in the oceans. The past five years have been the warmest on record for the world’s oceans.

Scientists have proven that humans are the main cause of the constant warming trend. Planet-warming emissions from fossil fuels trap heat in the atmosphere, creating an energy imbalance. In turn, the oceans absorb 90% of the excess heat, causing temperatures to rise alarmingly.

Jeff Masters, a meteorologist at Yale Climate Connections, says most of the warming has happened in the top layers of the ocean, where storms get their energy.

“Hurricanes and hurricanes are heat engines, which means they take heat from the oceans and convert it into kinetic energy, which is wind,” Masters told CNN. “So if you increase the amount of heat in the ocean by heating it up, you’re not only increasing the maximum intensity they can get, but you’re also increasing the rate at which they reach that maximum intensity.”

A 2019 study found that Atlantic hurricanes in particular showed a “very unusual” rapid increase in intensity from the 1980s to the early 2000s – a trend that can only be explained by variations in intensity. anthropogenic climate change. And, the scientists found that the most dramatic changes were happening with the strongest storms, making the most life-threatening storms even more deadly.

“Climate change increases the likelihood that you will be rapidly augmented,” says Masters.

Some of the most destructive recent U.S. hurricanes were hurricanes that rapidly intensified just before landfall — something Hurricane Ian wasn’t expected to happen. Most recently, Hurricane Ida in 2021 strengthened from Category 1 to Category 4 in the 24 hours before making landfall in Louisiana and leaving a trail of devastation after it moved northeast from the Gulf Coast.

However, forecasters are increasingly understanding the signs of this phenomenon before it happens, which gives coastal residents more time to prepare for the worst.

Kossin says there are several reasons for this. One is that meteorologists are becoming more confident in computer forecasting models, which are improving at seemingly light speeds. The second is that they have seen more severe cases rapidly increase in recent years, which makes it easier to forecast them in the future.

Masters told CNN it all adds up to better forecasts.

“The forecasts are unprecedented mainly because [National] The Hurricane Centers are doing a better job of it,” said Master. The weather models are a lot better. And our forecasting techniques are getting better and better. “

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