The climate crisis is supercharging rainfall in hurricanes, scientists report

The rainfall from hurricanes during the deadly, record-breaking 2020 season was as much as 11% higher because of the human-caused climate crisis, scientists reported Tuesday.

The study, published in the journal Nature Communications, found global warming supercharged hourly rainfall rates in tropical storms and hurricanes by 5 to 10%. When they looked at only hurricanes — the strongest storms — the increase was 8 to 11%.

"What that means is not only is climate change impacting our hurricane season, but it's also impacting the most extreme storms a little bit more," Kevin Reed, a climate and hurricane scientist at Stony Brook University and lead author of the study, told CNN. "So the key takeaway is that climate change is here, and that it's already affecting our hurricane seasons."

Hurricanes — also called tropical cyclones or typhoons outside North America — are enormous heat engines of wind and rain, feeding on warm ocean water and moist air. And scientists have become increasingly confident over the years the climate crisis is making them more potent.

Behind storm surge, flooding from rainfall is the second-biggest killer in landfalling hurricanes and tropical storms. Tuesday's study suggests the threat has already been increasing over the past few decades, and will likely increase more in the future, because warmer air can hold more water vapor, which leads to higher rainfall rates.

The 2020 Atlantic hurricane season was the most active on record, with 30 named storms. The season tore through the alphabet so quickly, officials had to use Greek letters as names starting in September. Twelve named storms made landfall on the US coast, including Laura and Delta, which devastated parts of the Gulf Coast.