Humans are responsible for the unfolding climate crisis and its effects have been with us for a while now. Quantifying just how much worse we are making the climate is not always an easy task, but for the record-breaking 2020 Atlantic Hurricane season, scientists have just now been able to work out the impact climate change had on rainfall.

As reported in the journal Nature Communications, the team found that during the season rates of extreme rainfall over the course of three hours were 10 percent higher than pre-industrial conditions. And that the extreme three-day accumulated rainfall was five percent higher than it would have been before 1850.

The season had 31 tropical or subtropical cyclones, with 30 of them becoming named storms, surpassing the previous record set in 2005. Back then, 15 storms became hurricanes while in 2020, 14 out of those 30 became hurricanes. Both years saw seven of these storms turning into major hurricanes.  

The model used in the study, based on the increased temperature on the surface of the Atlantic Ocean, revealed that the hurricane-strength storms have also gotten worse. The rate of extreme rainfall over the course of three hours for these storms was 11 percent higher, and the extreme three-day accumulated rainfall was 8 percent higher.

The record-breaking 2020 hurricane season caused the deaths of at least 417 people and led to $51 billion in damages, making it the sixth costliest hurricane season on record. And it is going to get worse if we don’t start acting on the pledges of COP 26.

“This work suggests that this warming will lead to yet further increases in North Atlantic hurricane season extreme rainfall rates and accumulated amounts,” the authors wrote in the paper.

Hurricanes in the Atlantic Ocean start as tropical disturbances, storms of at least 160 kilometers (100 miles) per hour that hold onto their shape for at least a day. These can eventually turn into a cyclone due to the warm ocean heating the air above and causing it to rise and interact with the disturbances. With average global temperatures increasing, cyclones are expected to increase. From cyclones to worse weather events, it very much depends on atmospheric pressure and air currents. And that once again is crucially affected by temperatures on the surface of the ocean and in the air. Increases in windspeed bring forth storms that can evolve into hurricanes.

The link between extreme weather events has been established and more research, such as this, is allowing scientists to put numbers to the changes.