As our climate warms, we’re experiencing higher storm surges and record rainfalls during hurricane season — which is also why these storms are becoming more destructive and costly.
Warmer oceans fuel storms
So why do hurricanes bring more rain in a warmer climate?
Evaporation intensifies as temperatures rise, and so does the transfer of heat from the oceans to the air. As the storms travel across warm oceans, they pull in more water vapor and heat.
That means stronger wind, heavier rainfall and more flooding when the storms hit land.
Sea level rise makes storm surges worse
Storm surge occurs when waters rise above their normal levels and are pushed inland by wind.
With Hurricane Katrina, it was the storm surge that caused the levees to fail, leading to destruction in the New Orleans area.
Storm surge was also responsible for an extra $2 billion in damage to New York City after Sandy hit in 2012, according to a Rand report.
This phenomenon is made worse by sea level rise, which is triggered by human-caused global warming as warmer ocean water expands and land ice melts.
The average global sea level has already risen by half a foot since 1900 — nearly four of those inches since 1970 — as countries have developed and populations have grown. Higher sea level can push more water inland during hurricane-related storm surges.
Hurricanes are slower and intensify faster
Slower-moving hurricanes are becoming more common in a warmer climate, and the rate of intensification of the storms is increasing.
Scientists are still debating exactly how those hurricanes are linked to climate change, but here’s the leading theory:
The winds that steer hurricanes move more slowly in a warmer climate. Because warmer oceans transfer more heat to the air — and heat fuels storms — storms get more intense faster.
Hurricane Dorian, which hovered over the Bahamas for more than two days in 2019, helps illustrate those conditions.
Traditionally, hurricanes move forward at 10-35 miles an hour. Dorian crawled at 1.2 miles an hour, after quickly strengthening from a Category 2 storm (winds of up to 110 miles an hour) to a Category 5 (winds of 157 or more miles an hour).
The catastrophic hurricanes in recent years show we need science more than ever to help us prepare for — and act on — climate change.
Act when it matters most