Scientists have a new way to measure rain, or rather, rain intensity.

They looked at data from 185 weather stations across the globe, from 1999 to 2014, to determine how much rain fell in how many days.

They found that, on average, one twelfth of an area’s rain falls in its single wettest day, one eighth in its wettest 2 days, and half in just 12 days.

They decided to standardize this metric—the number of days it takes for half the rain to fall—as a way to gauge rain intensity in an area.

This is important because it’s intense rain that overwhelms the soil‘s capacity to absorb water, or the ability of a drainage system—of storm sewers, creeks and rivers—to carry water away, leading to floods, landslides and other impacts.

Scientists then projected what a warming atmosphere might mean to rain intensity.

Since warmer air can hold more water vapor, we could see more rain overall. This might be good news for places that don’t get enough rain.

But in already rainy areas, the increased rainfall may occur within its highest intensity rain days. The single wettest day could see 20 percent more rainfall.

This could occur while population, and the cost of infrastructure, continue to rise in coastal cities around the world, putting more people at risk of flooding, with more need for better flood warning and management.