Across much of the Carolinas, people who haven’t already fled are bracing for massive rainfall from Hurricane Florence, more than 40 inches in some places. They can blame climate change for much of that misery, according to a novel new study that estimates how much climate change has “supercharged” the hurricane.

Florence, now a Category 2 storm, is slated to make landfall early Friday morning, but the Carolinas could start feeling the impacts on Thursday.

The study, led by researchers at Stony Brook University in New York and the Lawrence Berkeley National Laboratory in California, is a bold new step for the science of climate attribution, which assesses global warming’s fingerprints on extreme weather events.

Every time a weather disaster strikes, people want to know if and how climate change is involved. Scientists have raced to get answers out faster and faster. Now they’ve provided one before a storm has even struck land.

The researchers ran computer simulations of the hurricane under two sets of circumstances. First they used conditions predicted by current weather forecasts, then they subtracted the effect of climate change on temperatures and the amount of moisture in the atmosphere.

There was a big difference between the simulations. “We find that rainfall will be significantly increased by over 50% in the heaviest precipitating parts of the storm,” the researchers said, in a summary of their research released on Wednesday.

They also estimate that Florence, currently measuring about 500 miles across, will be about 50 miles wider when it makes landfall than it would in a world in which human activities had not warmed the planet.

Climatologists contacted by BuzzFeed News warned that there’s some big uncertainty around how much global warming has increased the menace from Florence. But they’re impressed that the researchers came up with an initial estimate so fast.

“This is indeed lightning speed,” Katharine Hayhoe, a climate scientist at Texas Tech University in Lubbock, Texas, told BuzzFeed News by email. “Of course, in order to be conclusive, we will need to see multiple studies using different methods and approaches, but this initial estimate is very impressive.”

“You should be cautious about the quantitative conclusions,” Gavin Schmidt, a climate scientist at NASA’s Goddard Institute for Space Studies in New York City, told BuzzFeed News by email. “But, yes, that people are doing this credibly is new and very interesting.”