In 2020, Central and North America experienced an unprecedented hurricane season with a torrent of storms hitting the North Atlantic, and it seems that climate change supercharged these storms by increasing the amount of extreme rainfall by up to 10%, according to new research.
At least 400 people were killed in the series of violent storms two years ago in Central America, the United States and the Caribbean, with torrential rain, ferocious winds and flooding causing tens of billions of dollars in damages.
The record 30 named Atlantic storms in the 2020 season were so numerous that authorities ran out of their standard names and had to resort to a backup list for only the second time.
Scientists estimate that global warming is increasing the intensity and frequency of massive tropical storms.
Researchers looking at the 2020 hurricane season compared the precipitation generated by these storms to models estimating those that would have fallen without climate change, so with similar temperatures to the pre-industrial era.
"The main finding of our study is that human-induced climate change increased the extreme rainfall associated with the 2020 hurricane season by 5-10 percent," said lead author Kevin Reed, of the School of Marine and Atmospheric Sciences at Stony Brook University.
Researchers looked at two phenomena responsible for flooding: intense rain over a short period and continuous rain over a longer period.
Overall in 2020, they found climate change increased the volume of rain falling on the three worst days by 5%, and by 10% during the three most intense hours.
But for storms that ramp up into powerful hurricanes, the study found that the climate change effect is magnified, with an increase of 8% for the three worst days and 11% for the three most intense hours.
"This increase in the anthropogenic signal in rainfall from hurricanes compared to rainfall from all tropical storm strength storms is an important finding with direct consequences for coastal communities," the study said.
Due to greenhouse gas emissions generated by human activities, the planet as a whole has warmed around 1.1 degrees Celsius (2 degrees Fahrenheit) since pre-industrial times.
Previous studies have shown that this warming has increased hurricane-related rainfall during other years, including Irma in 2017, Harvey in 2017, Dorian in 2019.
Researchers said the latest study suggests similar effects could be happening in other parts of the world.
They said it also adds weight to the idea that warming "will lead to yet further increases in North Atlantic hurricane season extreme rainfall rates."