STEVE INSKEEP, HOST:
We have a long-range weather forecast for California. Weeks of storms have soaked the state, of course, without quite ending a long-term drought. The atmospheric rivers, as they're called, have been enough to bring hurricane-level winds, snow on the Hollywood sign, even a couple of tornadoes. At least five people were killed in the most recent wave of storms. We've called Noah Diffenbaugh, who's a climate scientist at Stanford University.
Welcome, sir.
NOAH DIFFENBAUGH: Thanks for having me.
INSKEEP: How's the weather?
DIFFENBAUGH: It's been stormy. This week was pretty wild on campus here and throughout the Bay Area, and, yeah...
INSKEEP: Meaning that you need the coat. You can't - you're getting wet.
DIFFENBAUGH: Yeah, we got really wet.
INSKEEP: OK. Is there reason to expect that this is what's going to happen in California from now on, this is going to happen all the time?
DIFFENBAUGH: Yeah. This is really consistent with our understanding of climate change. It was predicted way back in the 1980s that global warming would cause California to have, you know, more severe, protracted, hot, dry periods punctuated by extreme wet conditions. And that's exactly what's happened. And it's exactly what we're experiencing now.
INSKEEP: I'm interested that you say punctuated, meaning we are now in a period of these atmospheric rivers, which we've described in this program, bringing more and more moisture in off the Pacific. You're thinking that's going to stop at some point, and there'll be another desperate drought situation?
DIFFENBAUGH: Yeah. So if we look at the past decade or so, we had a record-setting drought and then really wet conditions. You might remember the Oroville Dam crisis from about five or six years ago. Then following that, we had another historic record-setting drought, and now, you know, that's being interrupted by what we're experiencing this winter. So, you know, this is, you know, a pattern that that we've been living through. And it's, again, very consistent with what our understanding is of how global warming should affect climate here in the region.
INSKEEP: We have reported in the past on the chances of a megastorm, which - I get the impression that would be something even worse than what you're experiencing this winter. What are the odds of that?
DIFFENBAUGH: Well, so we know that in California's history, when many of these atmospheric rivers come in succession, that it's caused extremely widespread flooding in the state. And the concern with global warming is that, you know, now we're in a climate where there is more moisture in the atmosphere. The storms that are happening are warmer. They're producing, you know, more rain relative to snow. That means more runoff when they happen. And so the concern is that if we get, even by bad luck, another one of these really long runs of atmospheric rivers, that the amount of flooding that's produced could be even more than what we know happened back in the 1800s.
INSKEEP: Knowing the science and the history that you do, as you drive around your native state, as you look around at the roads, at the houses, at the landscape, do you think that California is built for this change of weather to survive it, to endure it?
DIFFENBAUGH: Well, it's clear that here in California, we have a water system and a, you know, disaster risk management system that was designed and built in an old climate. You know, our water system is - you know, goes back 50, 100 years. Our legal rights for water go back a century. And we're now living in a new climate. We're living in a climate that's different than the one that our really sophisticated systems were designed and built for. And the question is, you know, how do we not just catch up with the climate change that's already happened, but how do we leapfrog ahead to the continued climate change that we know is going to happen in the future?
INSKEEP: OK. It's not that the climate is changing. It has already changed. Mr. Diffenbaugh, thanks so much.
DIFFENBAUGH: Thanks for having me.
INSKEEP: Noah Diffenbaugh is a climate scientist at Stanford University. Transcript provided by NPR, Copyright NPR.