“It just hit 40 C at Heathrow,” Friederike Otto, a 39 year-old climate scientist at Imperial College London who studies extreme heat, emailed me from her home in the Southwark borough. 40 degrees Celsius is 104 degrees Fahrenheit — the hottest temperature ever measured in the U.K. All around London, railroad tracks were bending and fires were breaking out and people were suffering in the otherworldly heat. Even for Otto, it was a bit surreal. “It’s eerily quiet,” she told me. “Very few cars on the road, and few people out in the street. Even my dog finally found her sense of self preservation and is lying in the basement (after she was insisting on sun bathing yesterday).”
Otto is not a conventional climate scientist. For one thing, her work is overtly political, even – dare I say it – moral. She is a pioneer in a new field called event attribution, which sets out to prove, often in real time, to what degree an extreme weather event can be said to be “caused” by climate change. Otto is the co-leader of World Weather Attribution, a research collaboration that quickly analyzes how (or if) climate change has made an extreme weather event more likely, more intense, or deadlier. After the Pacific Northwest heat wave last year, it took Otto and her colleagues only nine days to determine that it would have been “virtually impossible without human-caused climate change.” The implications of extreme weather attribution are enormous, not only because it gives us a clearer picture of what climate change is doing to our world, but because it is the first step towards holding big polluters (and the politicians who back them) responsible for the losses and damages that burning fossil fuels cause. Last year, Otto and Geert Jan van Oldenborgh, her partner at World Weather Attribution, were named in Time’s annual list of the 100 most influential people in the world.
Otto grew up in “excruciatingly boring” rural northern Germany. She studied physics at university and went on to get her Ph.D in philosophy. “I only started working on climate science after my PhD,” she says. (When asked by an interviewer to pick four words to describe herself, Otto, who is openly bi-sexual, said “Physicist, wannabe-dancer, media-go-to-scientist, theatreland.”) Extreme event attribution has been a goal of climate scientists for decades, but the process has been too slow and hazy to be really useful to shape public perception about extreme events. Otto and her colleagues revolutionized the field by combining multiple sources of evidence and modeling scenarios to bring speed and rigor to the process. They created what amounts to a rapid-response team to track the arsonists in our burning world.
You’re a scientist studying heat waves in the middle of a heat wave. It’s like your subject has tracked you down.
Yes, absolutely. I am exhausted.
What have the last couple of days in London been like for you?
Well, actually, the temperatures only got exceptionally hot today here in London. Before that, we had several days with temperatures above 30 degrees C, which is something that used to be unusual in the UK and now is absolutely normal summer. And now, yeah, we are we are seeing temperatures up to 40 degrees C, which really brings home that we are absolutely not prepared for this. I walked down the street today and saw lots and lots of houses that have the windows wide open. This is not what you do in the middle of the day during a blistering heat wave. It just makes the temperatures a lot higher in your home. You have to close the windows, pull the curtains and ideally you have shutters outside that you can close. You only open the windows at night. And so really simple things like this is just something that we need to learn. In the UK, we just don’t know how to deal with heat.
How surprised are you by this heat wave in the UK? It’s pretty brutal.
I’m not surprised at all. We have known that these temperatures are now possible in the U.K. and that 40 degrees in London is really not something that extreme anymore because we have we are living now in a world that is a lot warmer already. Also, it was forecast almost two weeks in advance. We knew that this heat was coming.
Are surprised by the political response — or lack of it — to the heat?
The Tories, who are trying to figure out who is going to be our new Prime Minister, just treat climate change as a future problem that we can deal with, but it’s really not actually that important. And some of the candidates for the Prime Minister job are even thinking about going back on some of the promises that have been made. And I find this surprising because, well, one of the things that was good about UK politics — and there’s really not a lot good to be said — was that climate change was not a partisan issue. It was something that was registered as an important issue by all parties. We actually have the Climate Change Committee which advises the government. And so this was something that was dealt with in a much less politicized way in the UK than it used to be in other parts of the world. And so to see us going back on this at a time when climate change is really punching us heavily in the face …..ugh, I shouldn’t be surprised. The Tories think that politics can be made for rich white old people only.
Is it about money, about lobbying power of the fossil fuel industry?
Well, it’s is for sure partly about money and lobbying. But I think also that, in UK politics, there’s a problem of a lack of an alternative. Labor is not saying anything on anything. There is just a real vacuum.
Let’s talk about the science of heat waves. You have said that climate change is reflected in heat waves more strongly than anything else. I think most people understand that. The planet’s getting hotter and heat waves are a direct manifestation of that. But you have also said that intense heat waves are an extremely complex sign of climate change.
On the one hand, as you said, it’s really simple. We have more greenhouse gases in the atmosphere. The atmosphere is getting warmer. We see more heat waves. They are hotter. That is really straightforward and very simple. But when you want to say how much hotter a heat wave has gotten or will get with future climate change, you find that these sort of large scale changes we understand very well don’t work so well at a more local scale. For example, for Europe, all the climate models we have underestimate the change in heat that we observe. On the other hand, for the U.S., most of the models overestimate the change in heat that we observe. We don’t know why. In the U.S. there are some things, such as irrigation changes and so on that has influenced some of the data, but that’s not the whole explanation. There’s clearly something that changes heat on local scale that we don’t understand. And this is why putting exact numbers on it is really difficult.
And heat waves also have very different impacts. It’s well understood that we have an increase in mortality with heat waves. And yes, we have statistics in some parts of the world where we see that hundreds and thousands of people die every year because of extreme heat. But in many parts of the world, we don’t have these numbers. So we don’t really understand how different people are differently affected by heat. And of course that is important if you want to know how to prepare and who is most vulnerable.
Then there are economic impacts. If you have a hurricane or a flood, the economic impacts are quite clear and well documented. The insurance industry has amazing statistics about that. The economic impacts of heat waves – well, no one has ever bothered measuring them, really. So we do know that it reduces labor productivity, and that has economic impacts. And we do know it affects infrastructure. So here in the UK, for example, we have lots of road and railway closures because the infrastructure systems can’t deal with it. And we know that it has impacts on power prices because the nuclear power stations can’t run because they have to be shut down when the cooling water gets too hot. So there are lots and lots of impacts — but they have never been assessed comprehensively. And this is one of the reasons why we have ignored heat waves for such a long time as a really serious issue.
And all of these impacts particularly affect those most vulnerable in our society. It’s not the rich and healthy who die in a heat wave. It’s those with preexisting medical conditions living in poorly insulated houses that die.
And what about food supply? As we’ve seen with India earlier this this year, the heat wave in India and Pakistan had huge impacts on the wheat harvest in India that led to the Indian government putting a ban on wheat exports, which meant that there was a lot less wheat on the global market. Food prices were already really high because of the war in Ukraine, but the export ban pushed food prices even higher, which of course affects those with the least economic means and the poorest in our societies.
It is true. And it’s weird because when we talk about climate, we often use the phrase “global warming.” Still, the impacts of heat have been so misunderstood and so unexplored.
Yes. And because there is this idea that all our problems have to have a technological fix. So people seem relatively happy to say, okay, flooding is an issue. So we build some seawalls and then be done with it. Whereas you can’t build a sea wall against a heat wave. You really have to completely redesign your cities. And so you have to change your behavior and do lots of these things that no one wants to do.
That’s a great point. Let’s go back to the science of heat waves. Your expertise is in attribution. Is it fair to say that climate change is clearly the driver of all of these heat waves that we’re seeing right now?
Yes. But of course, not the only driver. There’s always a role of just the chaotic variability of weather. There are also things like land use changes that play a role. But we have many lines of evidence now showing that heat waves have gotten hotter and longer and more frequent because of climate change. We don’t really need to do an attribution study to know that climate change made them worse. We do need to do an attribution study if we want to disentangle exactly what these drivers are and want to know how much more likely [heat waves will be].
And in that context, what aspect of this heat wave you are living through right now do you want to understand more deeply?
So we know that heat waves are getting hotter, more frequent. And we understand how warming is driving this quite well. But changes in atmospheric circulation are more complex. There are some studies that suggest that, for example, the Azores high [a large semi-permanent center of high atmospheric pressure south of the Azores in the Atlantic Ocean] is lasting longer…. If there are changes in the atmospheric circulation, that would be one explanation of why our models underestimate what we see in observations. So how the atmospheric circulation is changing and what role that is playing in these European heat waves is something that I would really like to understand better. Also, just comprehensively assessing at least the lower bound of the economic impacts so that we can finally go to policymakers and the insurance industry and say, look, this is how much a heat wave costs. You really have to do something about it. I think that would also be really important because these numbers can be quite powerful and we don’t have them at the moment.
How close are these attribution studies to being accepted in a court of law? I mean, it would obviously be very useful if you could say, ExxonMobil, your contribution to warming is 3 percent. This heat wave had damages of, say, $5 billion. Therefore, you are responsible for X dollars in losses and damages.
I think they are ready to be held up in court right now. I’d say five years ago it would not have worked because we only had individual studies and you could easily have done a study where you just do the framing slightly differently and come up with different results. Now we have really a huge body of literature, and it shows which aspects of an attribution study are quite sensitive to framing. So for example, if a heat wave gets ten times or a thousand times more likely, it really strongly depends on how exactly you define heat wave — whether you just look at the one day maximum temperature or whether you look at the whole summer or something. So you get very different numbers. But when you look at the change in intensity, such as saying that this heat wave was two degrees hotter than it would have been, that is quite consistent. So because we have this understanding of which aspects are sensitive and we have this huge body of literature, I think that we have what is called in legal terms “the causal field.” So we have established this causal field at least for heat waves. We don’t have this causal field for changes in hurricane frequency and intensity yet. But for heat waves, it’s very strong.
A big part of reducing vulnerability to heat waves is increasing awareness of them. There is a growing movement in several countries to name heat waves, similar to the way we name hurricanes. What do you think of that idea?
I think that is really helpful. In 2017, there was a heat wave here in Europe that was called Lucifer, right? I think naming is quite powerful because it makes it easier to talk about it, which is quite important. And then yeah, people know that if the storm has a name, it’s a serious storm. Or heat wave.
Let’s talk about the future. In a recent paper, you basically argued that the past is no longer useful for thinking about the future when it comes to heat extremes. We’re in a new era now, and the changes we’re likely to see are difficult to predict – and so difficult to prepare for. Can you explain what you meant?
Yeah. So what we do with attribution studies is say, what used to be a one in 100 year event is now a one in 50 year event or something like that. So for events like heavy rainfall, it’s still something that you can estimate from your observed records. And so the kind of measures you put in place to protect yourself from flooding are still useful. You just need to prioritize them. Whereas for heat when you look at observed records, it’s not much help. So the heat wave in the Pacific Northwest last year was a really good example. When you use the whole observed record, including every year leading up to 2021, and you do your usual statistics based on observations, which is how city planners and insurers think about future risk, you would think that it’s not possible to ever see a heat wave like the one they had. So from a purely statistical point of view, the observed record is useless. This is not true, for example, for hurricanes. But for heat waves, the atmosphere is changing so fast that it will be completely useless to look only at past data and it would lead to the wrong assumptions of what’s possible.
Right. Which leads me to another question, which is, what do we need to prepare for? I mean, there was a 70 degree Fahrenheit temperature spike in Antarctica this year. If that happened in London or New York it would kill hundreds of thousands of people. You know, parts of Pakistan and India are hitting 50 degrees C, which is close to the limits of what humans can survive. What are the boundaries here? Are we going to see a 55 degree day in India where everybody who is not hidden in an air-conditioned room just drops dead from heat stroke?
Well, really, the upper boundaries depend on one thing: At what global temperature do we finally stop burning fossil fuels? When you lift the global temperature, you lift that ceiling. And how how much further it will lift it is really crucial and it depends on how much more fossil fuel we are going to to burn. So I think 53 degrees C in Pakistan or India would be totally possible already today. And it certainly will be if we have a two degree warmer world.
But the ceiling is completely different depending on where in the world you are. So you would never see a 70 degree Fahrenheit jump in temperatures in New York. Just because the climate is very different and a lot less variable from year to year than in Antarctica. So the temperature jumps in Antarctica and the kind of jumps that are possible in London or New York are very different. But as long as global temperatures continue to rise, the ceiling will rise too. The more fossil fuel we burn, the more dangerous the world becomes.
So when you look at what’s happening right now in the summer of 2022, when heat records are being broken around the world and tens of thousands of people are suffering and dying of heat, what worries you most?
I think what worries me most is that we continue to see one crisis played against another. So climate change was an issue that was taken apparently seriously around the United Nations Climate Change Conference in Glasgow last year. And then the war in Ukraine happened and now it’s energy security that everyone is thinking about and climate change is completely irrelevant. So in Germany we see coal-fired power plants that had already been shut down are now going back online. And while you can say this might be a sensible thing to do, it would only be a sensible thing to do if you have to make sure that they will be shut down again immediately and that this does not affect the plan to eliminate coal that was in place. But that’s not the case. There are lots of loopholes that would allow Germany to keep the coal plants running for another decade or something. And this is what worries me most. We don’t seem to understand that climate change is not something that can be treated in isolation. These crises need to be addressed together. What we ultimately need to do to address climate change is to reduce inequity and inequality so that we can reduce our vulnerability. And a lot of the things that we need to do to redesign our cities to cope with heat actually do help energy security. But that’s not how these problems are addressed. They are always looked at in isolation. Climate is a crisis that unites everything. It’s not something we can look away from.