Extreme Rainfall Events Could Increase Almost 50 Percent Over The Next Century

If you don't have a raincoat, now might be the time to invest in one. A study published in September in Geophysical Research Letters found that we could see a 50% increase in cases of extreme rainfall over the next century if climate change continues at its current rate.

The problem is that when the atmosphere gets warmer, air holds more water, the researchers said. The new study found that based on climate models, this could lead to a big increase in extreme rainfall events over time - like the recent devastating flood in Colorado.

Right now, these cases of extreme rainfall only come about once every 50 years. But the researchers found that this could change if the atmosphere continues to warm.

The researchers gathered information on trends of extreme rainfall from 1966 to 2005, and used that information to create projections of how many occurrences of extreme rainfall we can expect from 2020 to 2059 and 2060 to 2099. For the study, extreme rainfall was defined as incidents in the top 10% of rainfall events in any given area, historically.

The researchers took the results of eight different simulations to create models of rainfall amounts projected for both time frames, and the team of researchers averaged the models together to calculate the average increase in rainfall we can expect over the next century.

The chart below shows the percent increase in the occurrence of those extreme cases of rainfall that are now only happening about once every 50 years. A and C show the winter and summer projections from 2020-2059, and B and D show the winter and summer projections from 2060-2099.

Areas in the middle and high latitudes of both hemispheres seem to be in for the biggest increase in extreme rainfall events. Other areas - colored in brown - seem to have lower potential for extreme rainfall. And the biggest impact will come in the second half of the century.

According to the 2060 to 2099 projection, places high up in the northern hemisphere that do not normally see much rainfall may experience a 45% increase in the fall and places far south in the southern hemisphere may experience a 39% increase during the spring.