Weather Events to Become More Extreme with Climate Change

Mar 10, 2020

A recent government report says that climate change is leading to extreme weather events that are becoming "more frequent, intense, widespread or of longer duration."  University of South Carolina geographer Kirsten Dow agrees, saying the historic 2015 rain and resulting flood caused by Hurricane Joaquin was a perfect example.

"The amount of water that was in that 2015 storm came off a warming ocean: the ocean was warmer, (thus) there was more energy available, more moisture in the air to be dumped on us in those floods.  And the same was true of Hurricane Irma.  It benefitted from warm offshore temperatures, picked up a lot more moisture than it would have regularly." 

The phenomenon is worldwide, said National Weather Service Science Officer Frank Alsheimer, as was demonstrated by the recent wildfires that devastated Australia.  He also cited Hurricane Florence in South Carolina, which last year had a kind of reverse effect on the state.  After it "dropped a tremendous amount of rain over the northern part of the state, lots of flooding associated with that...then we dried out in the spring, and in fact, in May of last year we had what we call a 'flash drought.'  Not only was it much hotter than normal, but it was also much drier." 

These changes can be compared historically because, said USC Climate Meteorologist Cary Mock, weather patterns can be monitored over centuries with varying methods (less scientific than today's technology, of course, but still useful) such as diaries and letters noting big weather events, and even ship logs.  "The British had ships in Charleston back in the 1700s, and they kept very detailed records of the hurricanes and how high the surge was."   Even tree rings yield information about past floods and droughts, he said. 

Weather extremes affect people in different locations differently.  Farmers are most directly affected by droughts, while people in coastal areas are hardest hit by hurricanes.  But Dow named one weather extreme that reaches everyone, regardless of occupation or location.

"The heat's the obvious one.  All over the world we've seen the hottest decade on record."  Heat will alter the workplace in the future, especially for those who work outdoors, she said.  "People are going to need more frequent breaks, they're going to need to start earlier, they're  going to need to shift their weekend schedules, because people are going to need to moderate their exposure to the heat." 

Alsheimer added that there are certain patterns that can be predicted about extreme weather in the  coming decades.  "We're fairly confident that you can expect more heat waves, the extreme cold to be less extreme than in the past, and rainfall will be more intense with certain storms, and drought is likely to be more frequent because we're likely to experience higher temperatures, which also leads to more evaporation." 

Whether the number of hurricanes will increase is hard to forecast, said Alsheimer.  But all the scientists agreed that warmer seas will increase their flooding effects.  The key to dealing with these changes, they said, is for cities to learn to become more resilient.

To that end, many coastal cities, including Charleston, have invested in resilience officers to help make plans to deal with situations caused by rising sea levels.  These plans will include a variety of steps, said Dow, from natural things like planting more trees to soak up more water, to people elevating their homes, to cities investing in infrastructure like improved drainage systems, because there is no one solution to the variety of extreme conditions the future will bring.