Last updated December 21, 2019

CO2 is changing the jet stream in ways that will create more Harveys

United States
Rescue boats fill a Houston street from flooded from Superstorm Harvey, August 28. Photo: David J. Phillip AP

The flooding over Houston has become absolutely devastating, and now it is officially record-breaking. Parts of Southeast Texas have now seen 50 inches of rain since Friday — and the rain is still falling.


“Many textbooks have the 60-inch mark as a once-in-a-million-year recurrence interval,” as the Washington Post Weather Gang reported Sunday.

We’re seeing these staggering rainfall totals because this tropical storm hovered in place for days over southeast Texas, sweeping in vast quantities of moisture from the warm waters in the Gulf of Mexico. And the latest science points a finger at climate change for this.

“The kind of stalled weather pattern that is drenching Houston is precisely the sort of pattern we expect because of climate change,” climatologist Michael Mann explained in an email to ThinkProgress. Earlier this year, Mann co-authored a study explaining how human-caused warming is changing our atmosphere’s circulation, including the jet stream, in a way that leads to “increase in persistent weather extremes” during the summer.

“I agree with Mike [Mann] that the weak steering currents over the south-central US coincident with Harvey are consistent with our expectations for a warmer world, which of course includes effects of a very warm Arctic,” Jennifer Francis, a climate scientist at Rutgers University, told ThinkProgress.

Francis is a leading expert on how global warming and the related Arctic amplification affect the jet stream and extreme weather. A study she co-authored that appeared in the Journal of Climate in June, concludes, “Over the central United States during summer, the weaker and wavier flow” of the jet stream favors “more intense summer weather.”