With Cuba and Florida left shivering afterwards Hurricane Ian, which made landfall in September 2022 and was one of the region’s most powerful and destructive storms in decades, it is tempting to attribute the slaughter of another deadly hurricane season to climate change. But is climate change to blame? Recent studies have linked climate change to the environmental conditions that fuel hurricane season, but the link between global warming and individual hurricanes is far from scientific knowledge.
While there is overwhelming evidence that human activities have directly caused sea level rise and global warming – both factors that make hurricanes more deadly – it remains unclear whether climate change fuel a significant increase in the number of hurricanes or intensify landfalling tropical storms.
“Hurricane activity occurs in the context of higher sea levels, which increases the risk of coastal flooding — that much is clear,” said Thomas Knutson, who studies climate change and hurricanes at the National Ocean Service’s Geophysical Fluid Dynamics Laboratory. and Atmosphere (NOAA). GFDL).
“The overall risk — how the frequency and intensity of storms is affected by global warming — is much more complex,” Knutson told Live Science.
Related: Hurricane Season 2022: How Long and What to Expect
A warming planet will typically give us more intense hurricane seasons, researchers have found. Rising sea levels due to climate change mean more coastal flooding from storm surges when hurricanes make landfall. And global warming is also affecting rainfall, with an estimated 7 percent increase in rainfall for every 1 degree Celsius (1.8 degrees Fahrenheit) of increased sea surface temperature, scientists reported April 12 in the journal Nature communications (opens in new tab). As human activities cause sea levels and surface temperatures to rise, hurricanes become more intense, in the form of flooding and heavy rainsLive Science previously reported.
Along these lines, some climate models have predicted that a 2 degree Celsius (3.6 F) increase in global temperatures would result in a greater proportion of hurricanes reaching Category 5 (sustained wind speeds of 157 mph or 252 km/h). would increase wind speed by about 5 percent on average and lead to more storms reaching the U.S., researchers reported in 2013 in Journal of Climate. In an earlier study, published in 2005 in the journal Nature (opens in new tab)scientists found such a strong correlation between Atlantic hurricanes and sea surface temperatures that they warned we could see a 300% increase in hurricane activity by 2100.
But despite these dire predictions, we have yet to see a significant increase in global hurricane activity. One confounding factor is that while warmer sea surfaces are ideal breeding grounds for hurricanes, storms that collide with a warm atmosphere tend to die out before doing much damage, researchers reported in Nature (opens in new tab) study published June 27. This may explain why, even as human activities have caused global warming of 1 C since the late 1800s, we have not seen an upward trend in the number or intensity of hurricanes over the past century — and why the study of nature (opens in new tab)found that climate change may be linked to a global decrease in the number of hurricanes.
“Increased greenhouse gases can cause warming of the sea surface, which increases hurricane intensity,” Knutson said. “But there’s even more warming in the upper troposphere, and that puts the brakes on hurricane intensity.” will still result in a net increase of hurricane intensity, but not as much as if we only had sea surface warming,” he said.
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While we haven’t necessarily seen more hurricanes globally in the past century, there has been an increase in the frequency and intensity of hurricanes in the Atlantic basin over the past 40 years. But even this increase may not necessarily be due to climate change. Other factors, such as reduced production and use of aerosol products, which damage the Earth’s ozone layer, have had a surprising impact on global temperatures that may have temporarily affected hurricane formation, according to a 2022 study published in Advances in Science. While greenhouse gases cause global warming, aerosols block sunlight and cool the planet. When the U.S. began curbing aerosols, that dramatic reduction may have caused a temporary increase in temperatures that increased the frequency and intensity of Atlantic hurricanes, the researchers said.
However, it is possible that factors other than aerosols were responsible for this change.
“There’s been a big uptick in hurricanes in the Atlantic basin since 1980, but we don’t know if that’s a signal caused by greenhouse gases, changes in aerosol use, or just natural variability,” Knutson said.
Given the number of variables that can affect hurricane formation and strength, it is therefore “premature to conclude with great confidence that increasing human-induced greenhouse gases have had a detectable impact on past hurricane activity in the Atlantic basin,” according to an Oct. 3 report authored by Knutson for NOAA Laboratory of Geophysical Fluid Dynamics. The report cites ongoing concerns that the increase in storm activity in the Atlantic Ocean since 1980 can be attributed to a combination of factors, including declines in the production and use of aerosol products, worldwide volcanic activity and even physical variability.
However, Knutson added, climate change will almost certainly make future hurricane seasons more dangerous, with more frequent coastal flooding, increased rainfall and warming seas favoring the formation of more intense storms.
Indeed, the change has already begun. In 2020, researchers analyzed data from 4,000 tropical cyclones spanning 39 years, from 1979 to 2017, and concluded that hurricanes are getting stronger and large tropical cyclones are becoming more frequent — just as models predicted, Live Science reported.
“On average, we expect hurricanes to become more intense and have higher rainfall rates due to climate change,” Knutson said. As for Hurricane Ian, which caused hundreds of deaths and was Florida’s deadliest hurricane since 1935, according to The Washington Post“Instead of saying that Ian is a result of climate change, we would prefer to say that storms like Ian are probably more intense than they would have been if they had occurred in the pre-industrial era,” Knutson said.