Think of the Earth’s climate system as a pair of dice. You never know exactly how a roll will end. But some outcomes, like rolling a seven, are much more likely than others, like snake eyes. But when we warm the globe, we essentially load the dice to favor extreme outcomes, including some of the most unpleasant weather possible in the United States.
A new study, rapidly conducted in September and published Monday in the Proceedings of the National Academy of Sciences, finds that the dice are increasingly likely to roll some very unpleasant weather indeed. Global warming may not have caused Hurricane Harvey, which ravaged Houston over the course of a week earlier this year, but it made it much more likely.
The study argues that storms that dump more than 20 inches of rain on Texas are about six times more likely now than they were at the end of the 20th century. Hurricane Harvey dropped 20 inches of rain across a swath of the state, and it deluged some parts of Houston with a record-smashing 60 inches of rain.
Harvey-like hurricanes will only get more likely as the century wears on. Between 1981 and 2000, there was about a one-in-100 chance that a hurricane would dump 20 inches of rain on Texas. By the end of this century—from 2081 to 2100, as children today enter old age—there will be a roughly one-in-5.5 chance that such a flooding hurricane would form if global warming continues apace.