Hurricane Ian bears all the hallmarks of climate change

On Wednesday, Hurricane Ian barreled ashore Florida's Gulf Coast as a powerful Category 4 storm packing 150 mph winds, submerging coastal communities in more than 10 feet of storm surge and dumping nearly two feet of rain in some locations. Two days earlier, however, Ian was just a tropical storm, and its rapid intensification is just one of the signs of how climate change has transformed how hurricanes behave.

Over less than 22 hours, from Monday to Tuesday, Ian got 67% stronger, the National Hurricane Center said. That dramatic escalation fits the pattern of one of the characteristics of hurricanes that scientists have shown is linked to climate change.

In fact, the number of intensifying storms in the Atlantic and Eastern Pacific over the last 40 years has increased by 25%, according to data from the NHC analyzed by the Associated Press.

That trend is occurring in part because ocean temperatures have risen as a result of humankind pumping greenhouse gases into the atmosphere.

The world’s oceans have “absorbed 90% of the warming that has occurred in recent decades due to increasing greenhouse gases, and the top few meters of the ocean store as much heat as Earth's entire atmosphere,” NASA says on its website.

The Caribbean Sea, where Ian traveled on its way to Florida’s west coast, is now 1.8 degrees Fahrenheit warmer than normal, according to the AP, and studies have shown that warmer water fuels storms.

“It’s a known effect of climate change,” Greg Foltz, an oceanographer with the National Oceanic and Atmospheric Administration, told the Washington Post. “Increasing ocean heat is causing strong hurricanes to become stronger.”

The bulk of global surface and water temperature rise has come in the past few decades, as global concentrations of atmospheric carbon dioxide have had a more pronounced effect. Over that same period, Florida has been hit with its five previously most powerful storms on record, including two Category 5 storms, Hurricane Andrew in 1992 and Hurricane Michael in 2018, two measuring Category 4, Hurricane Charley in 2004 and Hurricane Irma in 2017, and the Category 3 Hurricane Wilma in 2005.

Hurricane Ian has now crashed its way onto that list, and while it will take days to tally the damage it will leave behind, another factor that almost certainly made the situation worse along Florida’s coast is that sea levels around the state have risen by roughly 8 inches since 1950, according to data from the NOAA. The cause of rising seas is two-fold: First, oceans have risen due to the increased melting of the polar ice caps. Second, when water temperatures rise, so does the volume of a body of water.

Simply put, stronger hurricanes making landfall along coastlines where seas have already risen 8 to 9 inches since 1950 and are forecast to rise another 8 to 9 inches by 2040 (and much more by 2100) is a recipe for disaster.

“A future Hurricane Ian, with the three feet of sea-level rise that is coming, will irreparably wipe out Central and Southern Florida,” climate scientist Peter Gleick, founder of the Pacific Institute, said in a tweet on Wednesday.

Yet while rising seas and peer-reviewed and widely replicated evidence that rising temperatures are super-charging tropical cyclones are now a matter of record, many experts shy away from drawing a straight line between climate change and any single weather event.

“I don’t think you can link climate change to any one event. On the whole, on the cumulative, climate change may be making storms worse. But to link it to any one event, I would caution against that,” Jamie Rhome, acting director of the National Hurricane Center, told CNN’s Don Lemon in a Tuesday interview.

While Hurricane Ian was not caused by climate change, per se, and there is no data to suggest that warmer global temperatures will result in a greater number of annual tropical cyclones, numerous studies, some of which rely on computer modeling, have linked the increased moisture in the atmosphere to greater hurricane rainfall totals in general.

Ian, meanwhile, is forecast to dump 10 to 20 inches of rain on central and western Florida, an area that has already seen more than 200% of normal rainfall totals over the last two weeks. That same section of the state, which includes Tampa, experienced its warmest summer in recorded history this year.