How much worse was that storm because of climate change?

We know that climate change causes weather to be more extreme, more often. Attribution science tries to nail down exactly by how much.

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  Hey, it's Flora, and you're listening to Science Friday. As you have likely heard many, many times, climate change makes weather more extreme and extreme weather more frequent. That we know. What has been more difficult to measure is exactly how climate change has influenced a particular weather event. For example, how much more intense was Hurricane Lala because of climate change? How much more likely was the flooding in Nepal? How much more deadly were India's heat waves this summer? A growing field called attribution science is trying to answer questions like these. Here to tell us about the field, the challenges of this work, and why it's so important is Dr. Joyce Kimutai.

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  She's a climate scientist for the World Weather Attribution Consortium at Imperial College London and for the Kenya Meteorological Services. Joyce, welcome to Science Friday.

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  Thank you very much, and thank you for having me here today.

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  Thank you for coming. Is that description of attribution science, how you define it? Is there anything you'd change or add?

• 1:21Speaker 02

  I think that's a perfect description. I mean, we could just say that, I mean, in very simple terms, it's just a subfield of climate science that tries to sort of put a number to the frequency and intensity of extreme events that we experience now due to climate change. So basically saying, is climate change really to be blamed? And if yes, to our extent, and if no, to our extent.

• 1:51Speaker 01

  You know, it's interesting because I've covered climate change for a long time, and I feel like I've heard scientists tell me in the past that we can't know how much climate change is affecting one particular storm or weather event. So this feels kind of new. I mean, what's changed?

• 2:07Speaker 02

  I think that was what was done or that was what was said almost 25 years ago, 20 years ago. And we couldn't attribute single events at that particular time because the science or the methods hadn't gotten there. But then that has changed since then. So now we have, science has improved, our methods have improved, and we can actually really look at individual events and see what the role of climate change is.

• 2:37Speaker 01

  Hmm, I mean, it sounds like difficult work or like there's a lot of variables to sort through.

• 2:42Speaker 02

  Yeah, so basically, I mean, to use very, in a very basic way of how we do this is that we look at the event in the climate of now. So let me just use an example of the West African floods that we experienced and we studied two weeks ago. So what you would want to start doing is to first understand what exactly happened during these events. So for example, for West African flooding, the cities along the coast, the Guinea coast, reported deaths close to, I think, 59 in Abidjan and another 27, 26 in Lagos.

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  Fatalities from the storm.

• 3:23Speaker 02

  Fatalities, exactly. So you look at those impacts and you say, where were these impacts reported? Right? So because you're trying to triangulate, understand where these extreme events happen. And in observation, you want to know, what is the climatology? What is the normal rainfall in that city? So Abidjan, for example, or Lagos, for example, what is the normal rainfall that happens there? And then you want to understand, okay, if the normal rainfall, where we call climatological rainfall, is 50 millimeters, for example, I'm giving an example, but then during this event, what was different? So you know that this was a rare event. You know, it's beyond the normal, right? And then the next step you want to do is that you now want to use climate models sort of to simulate that event, right?

• 4:07Speaker 02

  So you want, because essentially what we want to do is that we want to compare the weather of now or the event that happened now in this weather of 2026 versus the weather that would have happened in 1850s, right? Because this is what we call the pre-industrial climate or the counterfactual climate, which we consider as the climate before the onset of industrial revolution. And that is where we base our analyses on. So you want to say to your--

• 4:37Speaker 01

  To understand the impact of all of these emissions that came from industrialization.

• 4:42Speaker 02

  Yes. So basically, you want to say, okay, if this flooding that happened in West Africa or the cyclone Helen that happened in the United States, if it happened in 1850s, would it be this intense? Would it be this severe?

• 4:58Speaker 01

  Hmm. So why is this important to you? Why did you get into this?

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  I think it's, I find it a very fascinating field because it's very societally relevant field of science because then it really touches on everyday lives and livelihoods. Because weather affects literally everything and everyone, right? I mean, this is, when you go out there, you breathe that is weather. We eat that is weather. We move that's weather. So it's everything that affects us. And even now with climate change, it's a bigger, it's a bigger of an issue than ever before. So, and so I think to me, I felt that that's a fascinating thing to do. It's a fulfilling thing to do, to be able to communicate what this science means for society, to communicate what this science means

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  for economies, for our lives and our livelihoods.

• 5:48Speaker 01

  Yeah, where do you think this field of attribution science will have the biggest impact?

• 5:53Speaker 02

  I think it's having impacted most areas, but I see the key ones are on adaptation. So I see adaptation, I see loss and damage, I see litigation, for example, I see--

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  Like holding emitters accountable.

• 6:10Speaker 02

  I think it's the kind of science that really tells us, not just telling us, just blanketly saying that our climate is warm, but it's the kind of science that puts a number to that, right? So we know for sure that, so in general climate science, you know unequivocally that climate has changed, right? But I think attribution science tries to push that a little bit farther by saying, by how much, by who, and who needs to do what. So for example, now we see researchers going into like looking at individual contributions of emitters, right? To say, for these heat wave or for these impacts, this emitter is liable to this much, or this is the contribution of this emitter.

• 6:55Speaker 02

  So I see that with that, with that kind of science, then comes the big question of liability and responsibility and injustice, especially for communities at the forefront of the crisis.

• 7:07Speaker 01

  Hmm, that's really fascinating. Thanks for joining us today, Joyce.

• 7:11Speaker 02

  Thank you.

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  Dr. Joyce Kimutai is a climate scientist for the Imperial College London's World Weather Attribution Consortium and the Kenya Meteorological Services. Up next, the liability, responsibility, and justice part. If scientists are able to connect the dots between emissions and harm to communities, what comes next? And how might emitters be held responsible? That's what my next guest thinks a lot about. Maxine Burkett has a background in climate and environmental law, and she's a professor of climate, environment, and society at Stanford University. Maxine, welcome to Science Friday.

• 7:47Speaker 03

  Thank you for having me. It's a real pleasure to be here.

• 7:49Speaker 01

  Thanks for being here. So, so once you can connect climate change to a particular weather event, what kind of sort of new legal action is opened up by that knowledge?

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  Yeah, I mean, I think there are at least two important ways to think about this. Once you're able to make that connection and understand that it's climate change, our planners and policymakers can be held accountable for making better decisions to keep us safe. And so as emergency planners, for example, think about how to plan for a 500-year flood that's now happening annually, we'll see that the proper investments are made with respect to dams, with respect to roads and bridges, and their ability to withstand the new weather that we're experiencing as a result of the change in climate, as a result of these increases in sources. There's also the issue of litigation. So in order for the cities to manage those impacts that are happening now, whether it's heat extremes or, again, these flooding events,

• 8:44Speaker 03

  they are going to need to engage in pretty major investment for their infrastructure. Those actions cost money. And being able to make the connection between the sources of major pollution, which climate change really is a pollution crisis at base, and then the impacts as a result of climate change will allow for better arguments in the courtroom.

• 9:05Speaker 01

  So is the focus on specific companies? Or is it on, you know, an industry as a whole, on countries? Like, what scale are we talking about?

• 9:14Speaker 03

  Well, it depends. It can be at all of those scales, right? And so certainly at the domestic level in the United States, we're seeing a number of state and local governments bringing cases against major emitters, oil and gas companies, in some cases utilities as well, to seek redress for the impacts of climate change from the burning of fossil fuels, the extraction and combustion of fossil fuels. Many of those cases are in state courts. And then there's, of course, different ways to address this internationally. So for example, we have the UNFCCC process, the Framework Convention on Climate Change, that allows for opportunities to seek support from other governments through loss and damage for those most impacted, the countries mostly in the global south,

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  who are exposed to and most vulnerable to climate change.

• 10:02Speaker 01

  So give me an example of a case that's happening now that's using attribution science.

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  Yeah, the City and County of Honolulu, like many other municipalities, is suing the oil and gas company major emitters for local environmental damages and deceptive marketing from fossil fuel companies, major fossil fuel companies. Because Honolulu is experiencing a number of increased precipitation events, experiencing drought, heat increase, and all of those are pretty well linked to the change in, the increased emissions.

• 10:40Speaker 01

  Thanks to attribution science, presumably.

• 10:43Speaker 03

  Well, thanks to attribution science, absolutely. And so that financial compensation will help those local governments to pay for the massive damages that they will, are, and will continue to experience as a result of climate change.

• 10:57Speaker 01

  And this case is in progress?

• 10:58Speaker 03

  This case is in progress, is actually farther along in many cases. It is and likely will be impacted by another case, Suncor versus Boulder County, that's in front of the Supreme Court and will be heard this fall.

• 11:11Speaker 01

  So something to keep on our radars this fall, it sounds like.

• 11:14Speaker 03

  Yes, absolutely, something to keep on the radar because the ability for states and city governments to pursue compensation for, again, the massive investments that have been destroyed or will have to be made to make their cities more climate resilient will be significant.

• 11:31Speaker 01

  I mean, you mentioned pollution. Is that the template for this kind of litigation?

• 11:36Speaker 03

  I think so. I certainly address this in a way that I think is an accurate and accessible way to understand the climate crisis, right? What we're experiencing right now isn't normal. It's the result of pollution over decades, mostly from certain countries and entities. But we have solved pollution crises previously, including global crises like the ozone hole. And we also have the opportunity, with that understanding, with better science, to actually make better decisions to protect our communities, protect our households, ourselves, and to seek redress from those who are most responsible to help with the massive costs of those impacts.

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  Maxine Burkett is a professor of climate, environment, and society at Stanford University in California. Thank you for joining me today.

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  Thank you.

• 12:23Speaker 01

  This episode was produced by Rasha Aridi. Thanks for listening. I'm Flora Lichtman.