MILES PARKS, HOST:
Some Washington state residents are beginning to return to their homes after major flooding this week. Flood waters have started to recede after rivers reached record levels in part of the state. But officials warn it still could be weeks before some areas are safe to return. Scientists say this week's flooding is a peek into the future as climate change is expected to drive more frequent and more intense flooding in the Pacific Northwest. KUOW environment reporter John Ryan has been looking into this, and he joins us now from Seattle. Hi, John.
JOHN RYAN, BYLINE: Hi, Miles.
PARKS: So why has there been so much flooding? What exactly made this storm so damaging?
RYAN: Well, the Northwest got hit by a series of storms known as atmospheric rivers, and these are long, narrow storm systems that cross the Pacific Ocean. They funnel moisture up from the subtropics, hence their local nickname the Pineapple Express, and they're perfectly normal this time of year and how the Northwest gets a lot of its winter precipitation. But the bigger atmospheric rivers, they do cause flooding.
So in this case, our region was hit by two pretty big storms back to back that overwhelmed our rivers. And by the time the latest storm hit, the ground was already super saturated, and it just couldn't absorb any more water, so it all just ran straight into the rivers. And forecasters say we will have another atmospheric river arriving on Sunday.
PARKS: Whoa. So scientists also say that the Pacific Northwest should expect more of this as the global climate keeps getting warmer. How is climate change playing into all of this?
RYAN: So scientists say it's not clear whether these storms this week are already being fueled by climate change in a big way. But they say the science is clear that a hotter climate will mean more frequent atmospheric rivers and rivers that last longer and deliver more rain. And that's because, really simply, that warmer air can hold more water, and then it can unleash more of that water when it's time to rain, and that's expected to drive more flooding. And as the climate warms, we'll also be expecting more precipitation in our winters coming as rain instead of snow. And snow, of course, melts slowly over months, but rain can run off instantly and cause big flooding.
PARKS: I mean, is there anything the communities in the region can do to prepare for these changes? Are there ways to prevent this kind of flooding?
RYAN: Well, we can't really prevent the flooding, but we can, you know, reduce the damage. And so the damage from a big storm isn't just about how big the storm is but about how the region maybe has prepared for it in advance. So there are ways to reduce the damage, like by not building in dangerous places that are vulnerable to flooding or leaving flood-prone land unpaved whenever possible so the land can soak up the rain instead of, you know, shooting it off immediately into some nearby creek or river.
And this kind of approach can even work in cities where, you know, most land is going to be paved. I spoke with Meade Krosby. She's a scientist at the University of Washington's Climate Impacts Group.
MEADE KROSBY: Things like rain gardens, green rooves, permeable pavement, like, anything that can help absorb and slow down and spread out the water before it overwhelms our stormwater systems and causes flooding.
RYAN: And Krosby warns that these kind of adaptation strategies can really only work in the long term if the world also slashes the pollution from fossil fuel burning that keeps making our climate hotter and stormier.
PARKS: That's John Ryan from KUOW. Thanks for the update, John.
RYAN: You're welcome.
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