Play Live Radio
Next Up:
0:00 0:00
Available On Air Stations

Mass: Expect Intensifying Rains With Global Warming


Editor's Note: This story has been updated to include a link to Craig Welch's response. 

A warmer planet will certainly cause more intense rains in the Northwest and we should start getting ready for that now, says KPLU weather expert Cliff Mass.

Mass is a bit of a skeptic when it comes to predictions about the weather due to global warming. He’s taken it upon himself to challenge media and fellow climatologists if he feels they’re exaggerating, for example with extensive blog posts countering a recent series by the Seattle Times on ocean acidification.

“I’ve spent a lot of time trying to damp down some of the hype about climate change,” Mass said. “People claiming that all kinds of major things have already happened.”

Seattle Times' environment reporter Craig Welch responded to Mass' critique with a detailed blog post of his own, defending the science behind the series.

But Mass says that doesn’t mean climate change due to humanity’s output of greenhouse gases won’t happen in the future. And when it comes to Northwest weather, he says one thing is certain: We will get more intense rains because of warmer weather, particularly in the second half of this century.

Mass is part of a group of researchers at the University of Washington looking into how much change is realistic. Together with one of his graduate students, Mike Warner, he’s looked at climate models for the rest of the century to see how precipitation will be affected in the western U.S.

The answer: The heaviest precipitation will get as much as 30 percent stronger by the end of the century. He says the reason is strengthening of the “atmospheric rivers” or currents of moisture that come from the tropics and subtropics and cause the big rains, such as the ones that occurred in November 2006 or November 2009.

“That means more intense precipitation. That means greater potential for floods as we get into the second half of the century,” Mass said.

The good news, he says, is that we have plenty of time to prepare and adapt.

“We have some time. We have decades to get ready for this,” he said.

But he says it’s certain enough that he advises changes in our infrastructure now: things like expanding capacity of dams for better flood control or moving people away from rivers which will flood more frequently. 

“I think this is inevitable, due to the greenhouse gases. As the planet warms up, the atmosphere holds more moisture and that will result in heavier precipitation when we get these atmospheric rivers,” Mass said. “So what we must do now is adaptation, prepare for the changes that are inevitable.”


The weekly KPLU feature "Weather with Cliff Mass" airs every Friday at 9 a.m. immediately following BirdNote, and twice on Friday afternoons during All Things Considered. The feature is hosted by KPLU Environment Reporter Bellamy Pailthorp. Cliff Mass is a University of Washington Professor of Atmospheric Sciences, a renowned Seattle weather prognosticator, and a popular weather blogger. You can also subscribe to a podcast of “Weather with Cliff Mass” shows.

Bellamy Pailthorp covers the environment for KNKX with an emphasis on climate justice, human health and food sovereignty. She enjoys reporting about how we will power our future while maintaining healthy cultures and livable cities. Story tips can be sent to