It seems the frequency of especially heavy rain events is increasing. Is this true?

Dear Tom,
It seems the frequency of especially heavy rain events is increasing. Is this true?
— Edward Rowe

Dear Edward,

Yes, and it’s probably a result of climate change. Government research indicates human activity has increased the carbon dioxide (CO2) in the atmosphere by 42 percent above pre-industrial levels. CO2 traps more heat in the atmosphere, and a warmer atmosphere holds 4 percent more water vapor for every degree rise in average temperature. These conditions mean more vigorous storms. According to NOAA scientist Ken Kunkel, once-every-five-year storms in the U.S. in 2015 occurred 80 percent more often than expected. And 12 percent more record-breaking rainstorms occurred worldwide from 1981 to 2010 than would have happened without human influence, according to Oxford