Flooding Worldwide Fits Climate Change Models

12:09 minutes

a small train passes over a flooded landscape, with a road partially submerged
Flooding in Germany. Credit: Shutterstock

While the western United States is burning again this summer, other parts of the world are drowning. Germany, Belgium, and China saw floods this week after intense rainstorms that dropped many inches of rain in matters of hours, killing hundreds and displacing thousands. In Turkey and Nigeria, less deadly rain events throughout July have still flooded streets and destroyed homes.

And as climate change continues around the globe, scientists say these intense rain events will only worsen, putting flood-prone areas at risk of longer-lasting, and faster-raining storms.

FiveThirtyEight science writer Maggie Koerth talks to Ira about the rising cost of rain events under climate change. Plus, why climate change may be hurting monarch butterflies more than a lack of milkweed, a first step toward experiments in geoengineering, and how Australia’s cockatoos are spreading a culture of dumpster-diving.

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Segment Guests

Maggie Koerth

Maggie Koerth is a science journalist based in Minneapolis, Minnesota.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Later in the hour, talking with the US surgeon general about vaccines, COVID, and health in the US. But first, a wave of flooding around the world this week is throwing the spotlight on one of the predicted consequences of climate change– intense rainfall, flash flooding, loss of life, as areas face an increasing frequency and intensity of storms.

Hundreds are dead and more are missing in Germany, Belgium, China, Turkey, and Nigeria. And China’s floods this week have been called 1,000-year events. Here to talk more about this and other stories is Maggie Koerth, senior science writer for FiveThirtyEight. Always good to have you, Maggie.

MAGGIE KOERTH: Thanks for having me back.

IRA FLATOW: You know, I have seen some pretty terrible pictures from these floods, as I’m sure you have. Can you say more about how bad they’ve been?

MAGGIE KOERTH: Yeah, so these are just huge storms. The system that went across Europe, across Germany and Belgium dropped six inches of rain in 24 hours. And these flash floods killed at least 196 people. The floods in China, those are even more staggering.

So in the city of Zhengzhou they had a year’s worth of rain, more than 25 inches that fell in just three days. Reservoirs were overflowing. There are these videos. We could see people trying to pull other people out of mudslides. And there were some videos that were circulating around where you saw hundreds of people trapped on subway lines with water up to their necks, like they’d just been on the subway and the flash flood had come through and inundated it.

IRA FLATOW: We saw the floods in China being described as 1,000-year floods, something that’s only happening once every 1,000 years. But we’re seeing 500-year floods other places, 200-year floods. This is sort of becoming a name that doesn’t mean so much anymore.

MAGGIE KOERTH: Right. Yeah, so 100-year flood is kind of a misnomer. It is a way of talking about risk. It’s not saying that the flood, that you should expect it to happen only once every 100 years. What it’s actually referring to is a flood that has a 1% chance of happening in a given year. So that’s– a 100-year flood is a 1% chance of happening every year.

But that’s every year. That’s not a 1% chance of happening out of 100 years. That’s every year you have a 1% chance. So if you’re in a 100-year flood plain in the United States and you buy a house, what you’re actually having is over the course of your 30-year mortgage, you’ve got a 26% chance of being inundated at least once.

IRA FLATOW: And the way climate change is happening now, it could be more often.

MAGGIE KOERTH: Right. So what we’re seeing is a lot of these 1% chance in a given year floods are becoming much more frequent. Those same provinces in China that are experiencing flooding right now had, last year, what was considered historic flooding. And now they’ve topped it.

Studies have suggested that a two degree increase in global average temperature would raise the risks of extreme flooding events from one in 100 to one in 25 in that part of the world. And in Germany, you have these insurance reports that have estimated that severe flooding on the Danube River is going to happen twice as often as climate change progresses.

Meanwhile in Nigeria, their meteorological agency has been analyzing 13 flood affected regions over the course of like 40 years, and they found this rising trend in yearly rainfall. And they say that is likely to be a significant factor responsible for floods there. So you’re basically just seeing this pattern where climate change is increasing these torrential downpours, which are increasing the flood risk in places that were already flood prone.

IRA FLATOW: Let’s move on to your next story, which is also about climate change and specifically the plight of the monarch butterfly. We’ve heard a lot about the plight of the monarch over the years. What’s different about this?

MAGGIE KOERTH: Well, some researchers did a study where they used citizen science surveys and weather data to try to tease apart how much of that butterfly’s decline has been due to climate change as compared to all of these other things that are impacting it, including herbicides destroying its favorite food, milkweed, and migratory problems.

The models that the researchers built using that data showed that between 2004 and 2018 the amount that rainfall and temperature deviated from long-term averages was seven times more important than other factors in explaining the decline in monarch numbers. So basically, they’re kind of teasing this apart and finding that over the last 20 years it’s been climate change that has been having the biggest effect on monarchs.

Now, that doesn’t mean the herbicide isn’t an issue. I think a lot of people of my generation sort of grew up hearing that we were killing the monarch’s food. We need to plant more milkweed. In their study, what they found– that was primarily between 1994 and 2003– that was during that time, herbicide was the largest contributor to decline. But we’ve had this turnaround where we’re getting milkweed protection and milkweed planting. And after 2003 that really got going, and it left climate change as a bigger issue for the bugs after that point.

IRA FLATOW: So should I still be planting milkweed, then?

MAGGIE KOERTH: Yeah, you should. The butterflies still need it. But it just kind of shows that climate change complicates that. So for instance, I planted milkweed this year. My milkweed plants died because Minnesota is in the middle of a historic drought. With climate change you’ve got droughts. You’ve got flooding. You’ve got a lot of things that will kill milkweed plants.

You also have– these butterflies are very delicate creatures. And you get their temperature ranges out of whack by too much and that will affect them also. So it affects them directly, and it can affect their food supply, which affects them indirectly.

IRA FLATOW: Another story that’s really interesting and something we have talked about for years, and that is trying to change the climate by geoengineering our atmosphere. Talk about that.

MAGGIE KOERTH: Yeah, so well after finding those couple of stories about climate change that are admittedly kind of downers, as most climate change stories are, I ran across this piece on Live Science where, apparently, the first experiments that could lead to actual for real real geoengineering are scheduled for next year.

Geoengineering is this idea that we might be able to mitigate the impacts of climate change by essentially harnessing the powers of climate change, just in the reverse direction. So we know from history that these large volcanic explosions would cool the planet by filling the atmosphere with dust particles that basically keep sunlight from getting from space to the Earth.

There’s been many controversial discussions over the years about whether it would be possible or safe or even remotely a good idea to do that same thing intentionally without the whole destructive volcano part. And to that end, there is a team of researchers at Harvard that are working on a project called the stratospheric controlled perturbation experiment.

And so far, what they’ve done is a lot of computer simulations. So they’ve been sort of trying to see if we put what basically amounts to chalk dust particles into the upper atmosphere what would happen. And their computer simulations are showing that this could work. It could be successful at lowering Earth’s temperature. But of course, it wouldn’t actually stop global warming. That’s one important thing to remember about geoengineering, we’re talking about reducing a symptom temporarily, not actually solving the problem.

IRA FLATOW: You’re blocking some of the sunlight that would reach the Earth?

MAGGIE KOERTH: Right. And it only lasts for so long. Their first real-world experiment would not release any of these particles. What is tentatively scheduled for next year would be sending up this large helium balloon thing that they hope to someday use for particle injections and just testing its maneuvering systems and its scientific instruments. It would rise 12 miles up into the sky and return to Earth. But that’s a first step towards something a lot bigger.

IRA FLATOW: Yeah. So this is just an experiment to see if this thing might work. They’re not talking yet about, hey, everybody adopting this around the Earth because we don’t know what would happen if everybody adapted this around the Earth.

MAGGIE KOERTH: Right. Yeah, so they have a series of very small-scale proof of concept test experiments that they want to do over the next few years. And one of their arguments for why they should do this is that this kind of geoengineering is something that a rogue group of scientists, a country, could just decide to do. And having this kind of basic science research done, well, that would be helpful so we know what is likely to happen or how to make this safer, if somebody just decides to walk off a cliff and do it without any kind of international agreement.

IRA FLATOW: Because if they’re going to change the sunlight, you’d like a larger discussion than just a group at Harvard deciding to do that for the whole Earth.

MAGGIE KOERTH: Yes, you would.

IRA FLATOW: Please, Maggie, give me give me something happy to talk about at the end here.

MAGGIE KOERTH: Cockatoos, dumpster diving.

IRA FLATOW: Cockatoos? Wow, what’s going on?

MAGGIE KOERTH: Australia’s cockatoos have learned how to open dumpsters and rummage through the trash.

IRA FLATOW: How do they do this?

MAGGIE KOERTH: Well, so these cockatoos are– there’s several steps to this. So they’re kind of lifting up the trashcan’s lid at the front corner with the bill and then sort of holding it open slightly while they wobble their little feet towards the hinges. And then they just give it a big flip so that it flies open at the end.

And what is really interesting about this is that in surveys of all these suburbs around Sydney, Australia, back in 2018 there were only three suburbs where this behavior was being recorded. By 2019, it had spread to 44 suburbs. And I need to make the obligatory clever girls joke here because they’re just– they’re testing the perimeter fencing. They’re learning. They’re the dinosaurs. They’re figuring things out. It’s amazing.

IRA FLATOW: Wow. And these are these plastic rollies we all take to the curb. They–


IRA FLATOW: –with the plastic lid on it, they just flip them up?

MAGGIE KOERTH: They flip them up. And what’s more, researchers have shown that different cockatoos are using slightly different methods to open these dumpsters that they want to dive in. And those methods vary based on physical distance. So like the cockatoos that are furthest from each other, like in the suburbs that they live in, have the most difference in how they open the dumpsters, which sort of implies that they are socially teaching skills to each other, not just that the dumpsters can be opened but how to open them.

It’s not quite evidence of human style culture. Some of these outside researchers are saying, well, to prove that, they’d have to identify a distinct, unique can opening technique in a specific region, and that hasn’t really happened yet. But this is really kind of cool, that this trick is spreading. And these cockatoos seem to be picking it up from other cockatoos.

IRA FLATOW: Maggie, always a pleasure to have you. Thanks for taking time to be with us today.


IRA FLATOW: Maggie Koerth, senior science writer for FiveThirtyEight. She’s based in Minneapolis.

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About Christie Taylor

Christie Taylor was a producer for Science Friday. Her days involved diligent research, too many phone calls for an introvert, and asking scientists if they have any audio of that narwhal heartbeat.

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Ira Flatow is the host and executive producer of Science FridayHis green thumb has revived many an office plant at death’s door.

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