STEVE INSKEEP, HOST:
How did it happen that flooding has devastated several parts of the world at once? Waters rose in West Africa and Eastern Europe and in China and in parts of the United States. It's not unheard of for so many places to face storms at once, but it is enough to ask, what is changing in our climate? Alejandra Borunda with NPR's climate desk joins us now. Good morning.
ALEJANDRA BORUNDA, BYLINE: Good morning.
INSKEEP: So how bad are these floods?
BORUNDA: Yeah. They're really catastrophic for the people who are living through them, Steve. Like, last week in Eastern Europe, a storm dumped more than 14 inches of rain in just a few days.
INSKEEP: Wow.
BORUNDA: Yeah, I know. And in West Africa, nearly a million people have been displaced by intense rainfall in the last couple of weeks. And last week, rain burst a major dam in Nigeria. And then that's not all. This weekend in China, a massive typhoon forced the evacuation of about 410,000 people in Shanghai.
INSKEEP: Well, what do we know about whether climate change played a role in all of this?
BORUNDA: Yeah. I mean, the short answer is almost certainly yes, but we won't know for sure for a couple of weeks probably. It takes scientists a little bit to do these things they call attribution analyses, which pinpoint the human influence on weather events like these. But climate scientists can definitely already say that these kinds of events are exactly what they'd expect from a hotter planet. Sonia Seneviratne is a climate scientist at the research university ETH Zurich, and she's also a lead scientist for the Intergovernmental Panel on Climate Change.
SONIA SENEVIRATNE: We know that basically precipitation is becoming more intense with increasing global warming and also that such heavy precipitation events are becoming more frequent.
BORUNDA: And honestly, this is really well-established science. A lot of things in climate are really complicated, but the physics here are pretty straightforward.
INSKEEP: What do you mean by that?
BORUNDA: I mean, you might have learned in physics class, like, way back in the day that warmer air can hold more water vapor.
INSKEEP: Sure.
BORUNDA: And water vapor is what makes rain. So if there's more water in the atmosphere, it can turn into more rain. Here's Seneviratne again.
SENEVIRATNE: With each degree of global warming, we expect an increase of about 7% of the intensity of heavy precipitation events.
BORUNDA: And because of fossil fuel burning and other human things that we do, Earth has heated up about 1.2 degrees Celsius, or a little more than two degrees Fahrenheit.
INSKEEP: OK.
BORUNDA: And this part is actually really important. It's not that all precipitation is getting a little more intense. It's that the most extreme events are getting much more extreme, exactly like what we're seeing in parts of Eastern Europe and West Africa.
INSKEEP: Oh, OK. So where the hundred-year event - the massive rainfall - might have been 7 inches or 10 inches, now it becomes 14. It gets bigger and bigger. Is that purely because the air is warmer and therefore can hold more water?
BORUNDA: I mean, yes, your example was exactly right. And also, yes, that's definitely the clearest and most well-established factor here. But of course, there's more. It's climate. Angeline Pendergrass is an atmospheric scientist at Cornell University, and she says when there's more water vapor condensing, it releases more heat.
ANGELINE PENDERGRASS: And that has the potential to actually further strengthen that upward motion that's kind of driving the storms in the first place.
BORUNDA: So you get this intensification on top of the intensification. I think it's really important to remember, too - kind of to your point earlier - that floods are also about the built environment. Like, take Shanghai. The city is covered in miles and miles of impermeable surfaces like asphalt. So that means the water collects. And the city has been trying to turn itself into a so-called sponge city that can absorb the increasingly intense rain. But this week's floods really show that it has a long way to go.
INSKEEP: So it sounds like the climate is getting worse more rapidly than people can adapt in some places.
BORUNDA: That's definitely one of the big concerns here, and I think it just really points to this issue that we have to deal with, like, that we have to work on adapting even faster.
INSKEEP: Alejandra Borunda of NPR's climate desk, thanks so much.
BORUNDA: Glad to be here, Steve. Transcript provided by NPR, Copyright NPR.
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