What Recent Destructive Cyclones Tell Us About Climate

MICHEL MARTIN, HOST:

We just heard from people who are dealing with the damage from cyclones in Nebraska and Mozambique. Now, those locations bore the brunt of the damage, but in both cases, surrounding areas have also experienced devastating flooding because of heavy rain. We wanted to get a better understanding of what these powerful storms might tell us about the climate, so once again, we've called on Katharine Hayhoe, a climate scientist and director of the Climate Science Center at Texas Tech University to explain what's going on.

Welcome back, professor Hayhoe. Thanks so much for joining us.

KATHARINE HAYHOE: Thank you for having me.

MARTIN: Could we just start with the terms that many people are hearing in the news? What's the difference between a hurricane, a cyclone and what's being called a bomb cyclone?

HAYHOE: Well, tropical storms that are fed by warm ocean water are called different names in different parts of the world. So what we call a hurricane here in North America they would call a typhoon over in Japan, and they would call it a cyclone down in the South Pacific. But they're all the same type of storm that get their energy from warm ocean water. And we know that over 90 percent of the extra heat being trapped inside the climate system by all the heat-trapping gases we're producing is going into the ocean, where it is powering stronger storms.

Now, as an atmospheric scientist, any storm that has a low-pressure system at its center is a cyclone technically. And so the bomb cyclone that we saw over the Midwest was not a tropical storm fed by warm ocean water. It was a storm that rotates in a counterclockwise way. That's why we call it a cyclone. But it was called a bomb because it intensified so fast. The center pressure dropped incredibly, and that increased the power of the storm significantly.

MARTIN: Now, we know that there is a season for hurricanes and cyclones. But the two that we're talking about now that have caused so much destruction, you know, both in Nebraska and especially in southern Africa. Is there something unique about those two storm systems?

HAYHOE: These two storms exemplify exactly why we care about a changing climate. So often, we think it's a matter of the polar bears or maybe future generations who will be affected. But the reality is, we are being affected right here in the places we live today. And the No. 1 way that we're being affected is by climate change exacerbating or amplifying or super-charging naturally occurring events like hurricanes, cyclones and winter storms, making them stronger and making much more precipitation associated with them today than we would have 50 or 100 years ago.

MARTIN: Well, you know, to that end, the National Oceanic and Atmospheric Administration tweeted this week that widespread flooding will continue throughout the United States through May. And they say it's going to affect nearly two-thirds of the lower 48 states. So a single storm can't be the cause of that. Does this also say something about the climate? Or is this just one of those, you know, weird anomalies?

HAYHOE: What we see today is a combination of two things - natural variability, which means some years are wet and some years are dry, overlaid on top of a long-term trend. Because long-term, we see that winters and springs in the Midwest are getting warmer. And we also see this heavy precipitation is getting much more frequent. It has actually increased 42 percent already since the 1950s, according to the National Climate Assessment, which I co-authored.

So when we see a year like we see this year, we say, wow. This is really unusual. It doesn't mean that we won't have a dry year in the future - we will. That's natural variability. But what we see is that climate change is stretching or amplifying our extremes, making our weather conditions even wetter and making our drier conditions drier as well.

MARTIN: But NOAA also says that states like New Mexico, Texas, Colorado and Utah will be facing drought-like conditions. And we also know that there were drought-like conditions in Mozambique and Zimbabwe before this cyclone hit last week. So I guess, I think, a lot of people would wonder, how can that be? How can both things be happening at the same time?

HAYHOE: What's often happening is that we have a natural pattern of wet and dry, and then climate change is amplifying that pattern. So when the pattern is for storms to come along, as it is right now in the Midwest, there's much more water vapor available for those storms to sweep up and dump on us today in a warmer world than there would have been 50 or 100 years ago.

But when there's a blocking pattern that prevents storms from coming across the region, warmer conditions in that case actually enhance or exacerbate drought because more water evaporates from our soils and our streams and our rivers and our reservoirs. But the storms don't come along to gather it back up and dump on us. So, ironically, climate change can actually exacerbate our extremes at both ends of the spectrum.

MARTIN: Professor, we know that the - you know, obviously the effects are going to be different in different places. I mean, we know that, for example, in southern Africa, I mean, part of the death toll is because the building materials were such that that even caused more death. But is it sort of fair to say that people who are already vulnerable are paying the bigger price for this climate change? Is that a fair statement?

HAYHOE: That absolutely is. People who are vulnerable, people who are not prepared, people who are exposed to devastating weather and climate events already disproportionately suffer. And then when these events are getting supercharged by a changing climate, then they suffer even more.

And this is true right here in the United States as well as around the world. And that personally is the reason why I care so much about a changing climate - is because it is profoundly unfair. It disproportionately affects the people who have done the least to contribute to the problem in the first place.

MARTIN: That's Katharine Hayhoe, climate scientist and director of the Climate Science Center at Texas Tech University.

Professor Hayhoe, thank you so much for joining us.

HAYHOE: Anytime.

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