Hurricanes are slowing, which could be a big problem
Jun 09 2018
According to NOAA, inland flooding accounts for more than 50% of hurricane-related deaths each year. While this sounds like good news, it isn't: It's not that hurricanes' wind speeds are diminishing, but instead how fast the entire storm moves, a new study reports. In the Atlantic region, storms moved 20 percent slower over land, the study found.
The study published in Nature this week by United States weather experts shows the problem weather systems are taking longer to travel across the planet. A slow storm increases the risk of damaging floods.
Hurricane Harvey lingered over south Texas for more than a week last September, dumping up to 60 inches of rain that left most of Houston underwater and resulted in 93 deaths.
"The poles tend to become disproportionately warmer than the tropics do under global warming", Kossin said.
Kossin told Nature that a 10% slow-down in storm speed corresponds to a 10% increase in rainfall when a hurricane makes landfall.
For instance, it is expected that hurricanes will rain about 7 to 10 percent more per degree Celsius (1.8 degrees Fahrenheit) of warming, as the atmosphere retains more water vapor, Kossin explained.
Unhurried hurricanes also mean strong winds blowing more often over the same place and possibly more storm surge, Kossin said. However, scientists have struggled to isolate the impacts of climate change on the characteristics of extreme weather events.
This means the more time they spend above land, the more devastation they can wreak with rainfall and storm-induced damages. So it isn't clear just how much of the change that Kossin found is actually attributable to human-induced climate change.