For years powerful entities with vested interests, whether petroleum giants or conservative politicians, tried to deny a connection between human activity and extreme weather events. Dr. Friederike Otto, a trailblazing scientist from Oxford, provides the missing link

Friederike Otto.
Friederike Otto.Credit: horst friedrichs / Alamy Stock P

Yarden Michaeli Aug. 12, 2021 8:20 PM

When the water reached chest level and inched up worrisomely to the neckline, the passengers on the subway’s No. 5 line realized that these might be their last moments. One woman called her parents and gave them her bank account details; another was afraid to call her children, but uploaded a clip calling for help. All told, more than 500 people were trapped in this nightmarish scenario, which played out last month when torrential rains caused widespread flooding in the city of Zhengzhou in China. Water filled a subway tunnel and it took rescue crews four hours to get to the trapped passengers, 14 of whom didn’t survive.

The disaster in China is only one such event to have taken place this summer, which appears to be the moment when the climate decided to make it clear to the world that it cannot be ignored. Besides flooding there and, earlier, in Germany, a partial list of extreme weather events this summer includes an unprecedented heat wave in North America in which hundreds lost their lives; vast forest fires in Siberia, a region better known for its freezing-cold weather, which have left a city living under a dense cloud of smoke; a severe drought that has left about a million people on the brink of starvation in Madagascar; fires raging across Turkey; and huge downpours that disrupted the work of a number of London hospitals, where residents in need of medical care were asked to turn to alternate facilities. Fittingly, on the eve of the heat wave now being felt in the Mediterranean Basin, a local weatherperson who presented the temperature chart said simply, “We’ve run out of red.”

Whenever an extreme event such as these occurs, a question immediately arises: Are human beings responsible for it? And if so, to what degree? Until a few years ago, those questions remained unanswered. Climate is a complicated subject, scientists explained, and anyway, there’s nothing new about extreme weather. But that is changing now. Today answers are available, even if only in some cases. For example, a collective of international scientists showed that the soaring heat that struck North America would have been virtually impossible were it not for human impact on the planet.

That dramatic conclusion was made possible by “attribution science,” a trailblazing and dynamic research field. With its help, the question marks are fading and it is at long last possible to close the chain and show the connection between a specific natural disaster and human action. Thanks to one group of scientists who are expanding the boundaries of scientific orthodoxy, we may stand before a revolution in the way the world perceives the climate crisis. And if that were not enough, senior legal scholars and high-powered attorneys are seeking ways to employ the innovations produced by attribution science against the petroleum giants, in battles that evoke the mammoth lawsuits of recent decades against the tobacco companies.

“The ultimate aim is to provide scientific evidence for the whole causal chain,” climatologist Friederike Otto, associate director of the Environmental Change Institute at Oxford University, tells Haaretz. In her 2019 book “Angry Weather: Heat Waves, Floods, Storms, and the New Science of Climate Change,” she wrote, “We can state whether and to what extent climate change is manifesting in our weather. We can stand up to the energy companies and the mercenaries of doubt.”


These days Dr. Otto is one of the world’s busiest climatologists. In fact, that’s always been the case, though it’s been especially true during the past several weeks, following a succession of seminal weather events that took people’s lives across the planet, including in rich, powerful Western countries. Her e-mailbox bursts with requests for interviews from the world’s leading media outlets: The New York Times, The Washington Post, CNN, BBC and more. They want to speak with Otto because she and her colleagues have been able to shorten significantly the working time needed for attribution studies. They are capable of dissipating the fog in real time – at the very time that the world is asking, “What the hell is going on here?”

Otto and her colleagues are the authors of the study that found the connection between human actions and the heat dome that enveloped western North America at the end of June. With the world’s attention focused on the abnormal heat, Otto embarked on a race against the clock. Working ceaselessly, a team of 27 scientists was able to distill a conclusion within a mere nine days.

It usually takes months, even years, to establish and publish such findings. But Otto’s team has set itself a truly challenging goal: to supply the information when it’s most relevant – not like other scientists, after the story has been swept out of the news flow. “What is striking about the news coverage of the heat wave that has recently scorched parts of North America, is a general hesitancy to link it to climate change,” she wrote in a recently published column, which shed light on her motives for moving quickly. It’s Otto’s work that often makes it possible for editors throughout the world to publish unequivocal headlines.

For years, climate scientists explained that it was difficult to impossible to isolate the connection between humans and specific weather events. No one disputes that heat waves, floods and other natural disasters have occurred throughout history. Nor is there any dispute that Earth’s average temperature is increasing due to human activity, that icebergs are melting and ocean levels rising. But because climate is a complex, variable-rich field, it was always difficult to draw, with scientific certainty, a connection between human activity and the increase in the frequency and intensity of specific extreme events. In other words, the fact that the two developments occurred side by side – Earth’s temperature climbed and extreme weather events sowed destruction across the world – was not in itself sufficient to establish a causal connection. One could say that this is the difference between common sense and science.

This gap was exploited by powerful vested interests, from conservative politicians to oil companies. The petroleum giants invested billions of dollars to promote their agenda and to undermine the public credibility of climate science, using position papers, lobbying, pseudoscientific research institutes and public campaigns, which played constantly on the realm of doubt. Thus, over a period of almost 30 years, as researchers from Harvard wrote, the giant American oil corporation ExxonMobil paid The New York Times to publish a weekly ad – at $31,000 per throw – in many cases placed in a prominent place on its prestigious op-ed page. Week after week, every Thursday, the elite readership of the most esteemed newspaper in the world was exposed to the message of the Texas oil barons.

An ad published by Exxon Mobil in The New York Times in March 2000.

A typical ad, published shortly before the world’s countries convened to sign the 1997 Kyoto Protocol, stated, “Scientists cannot predict with certainty if temperatures will increase, by how much, and where the changes will occur…. Let’s not rush to a decision at Kyoto. Climate change is complex; the science is not conclusive; the economics could be devastating.” Another ad, from 2000, claimed that scientists “can’t prove the connection” between human activity and the floods and storms occurring at the time.

Versions of messages of that kind can still be heard, including in Israel. For example, whether intentionally or by mistake, a particularly outrageous explanation currently appears on the website of the Education Ministry, under the rubric of learning materials: “On the issue of global warning there is no unanimity of opinion in the scientific community… Warming is liable to heighten the frequency and intensity of extreme weather events, but it’s difficult to prove a causal connection between that and a given event.” Even in Haaretz a column was published not long ago that sharply attacked the scientific consensus, claiming, among other points, that “some of the extreme events are increasing, others are weakening. In any case, there is no direct proof of a direct connection between these changes and the global temperature.”

This is not only a scientific or educational problem. Without proof of a connection between human actions and specific damage, activists have found it difficult to promote legislation and regulation of the polluters. Large companies are capable of muddying the public discussion, and they are more than interested in doing just that when they are at risk of losing a great deal of money. Thus, the tobacco companies fought for years to blur the connection between smoking and lung cancer (“Doubt is our product,” is the most famous quote from the internal documents of the tobacco companies), the American gun lobby diverted the debate from legislation to personal responsibility (“Guns don’t kill people, people kill people”), and the discourse around climate science became rife with conspiracies of all types.

It usually takes months, even years, to establish and publish such findings. But Otto’s team has set itself a truly challenging goal: to supply the information when it’s most relevant.

Enter attribution science, which integrates sophisticated, powerful models and is capable of providing the link that closes the gap between your car’s exhaust pipe and the broiling heat that kills people. The first buds of the new field appeared at the beginning of the 2000s in an article published in the esteemed journal Nature. In it, scientists from Britain’s Meteorological Service for the first time drew a connection between human actions and a specific heat wave that caused the death of 70,000 people in Europe in 2003. In 2016, the National Academy of Sciences in the United States published a study that reinforced the general confidence in the method; and last year the prestigious MIT Technology Review characterized the field as one of the 10 breakthrough technologies of 2020.

One way to understand the indefatigable search of climatologists for information about planet Earth is to travel back in time to November 1881, when a maritime engineer named George Melville walked in the brutal cold of the delta region of Siberia and looked around him. Exhausted and hungry, he was searching for his colleagues – possible additional survivors from a disastrous journey that had begun two years earlier. They were crewmen from the ship USS Jeannette, which had sailed from San Francisco in search of a new route to the North Pole.

Cape Town

But instead of conquering the sea lanes, the Jeannette became icebound in the Arctic region, floating for two years in a frozen cage. One day the ice crushed the ship and it sank. The crew split up into three small boats in the icy sea. Melville, who commanded one of the boats, survived, and after multiple hardships, finally made it home with the logs containing the records kept by the ship’s crew. Along the way, he considered leaving the heavy volumes behind, but quickly changed his mind. “Setting my teeth against the storm,” he wrote afterward, in a book about the ordeals of the unfortunate mission, “I would swear a new oath to carry them [the books] through, let come what might.”

The logbooks contained observations of various phenomena – the aurora borealis, winds, barometric pressure and more. It’s unlikely that the sailors imagined that someday in the future the records they kept would be consulted by scientists seeking to gain a better understanding of the dramatic climate changes that would transpire on Earth – but that is precisely what happened. Today the records of the Jeannette, and those of many other journeys across the years, are deposited in the National Archives of the United States. They are being scanned meticulously and uploaded to the internet for volunteer weather buffs to decipher the dense handwriting and extract historical weather data.­

The logbooks project, known as “Old Weather,”is an exotic example of an information source for scientists, but it represents only one small piece of the vast puzzle that constitutes human knowledge about the world’s climate. That knowledge is growing incrementally over time, and as it does, a picture of the planet across history down to the present is coming increasingly into focus. A number of factors – powerful satellites orbiting in space, data collected rigorously from weather stations across the globe, digitization of historical information preserved in archives, and a surge in the ability of computers to perform complex calculations – have combined to create immense, detailed databases that make it possible for climatologists to say what they do with increasing confidence.

That mountain of knowledge is the basis of attribution science. A few more years were needed after that first study at the start of the millennium before the conditions ripened for a true breakthrough. One of the reasons for this, according to Otto, is that “the attitude of science to data has changed.” In contrast to the past, she explains, today many countries share with one another the data collected in their territory.


The lungs of the Argentines

Friederike Otto, 39, started as a physics student and completed a doctorate in the philosophy of science. She was born and raised in Kiel, in northern Germany, and today lives in Oxford with her family. Reflecting her outlook on the world, when she moved to that university town, she bought a house on a hill, intentionally distant from areas that are in danger of flooding in winter.

Otto is one of the leading authors of the latest report drawn up by a panel of scientists under the auspices of the United Nations’ Intergovernmental Panel on Climate Change, and released earlier this week. The name may sound dull to those not familiar with the field, but this report is actually the world’s gold standard when it comes to the most up-to-date and best-grounded scientific knowledge about Earth’s climate. To Otto’s great pleasure, the report, endorsed by scientists from across the world, embraces attribution science wholeheartedly.

Otto’s flagship project is World Weather Attribution, the international collective of scientists who have set themselves the goal of providing rapid answers about the connection between climate change and extreme weather events. Her co-leader in the project is Dr. Geert Jan van Oldenborgh, from the Royal Netherlands Meteorological Institute.

If, along with the weather forecasts, people were told how much of the rain or heat intensity was our fault, that might bring home the seriousness of climate change in ways that we haven’t managed to date. Gavin Schmidt, NASA

Most research groups that are engaged in attribution studies operate at the standard pace of the world of science. Research takes time, and getting the results of a study published in a scientific journal does as well. Indeed, when Otto and her partners decided to accelerate the process, she says, some scientists labeled them naïve and accused them of displaying hubris. But she and her team succeeded in improving the method and achieving a level of confidence that makes it possible to operate outside the accepted boundaries of the world of science.

In practice, they submit their studies for peer review, but they publish them long before the review process is completed, with the aim of supplying answers quickly, when they will possess a greater real-world impact. “Science should be on the offensive rather than the defensive,” Otto writes in “Angry Weather,” and adds in her conversation with Haaretz, “It was a deliberate decision to do science in the public eye. We got a lot of pushback from the scientific community at the beginning. But this has changed. Not completely, but a lot of people see the value in what we do.” And indeed, reading Otto’s book inspires a sense of activism, though this is far from the traditional stance taken by scientists.


Working in their unique way, the team has published many studies. And what do their findings suggest? One example pertains to Cape Town, which by 2018 was suffering from a drought so serious that the water in the city of four million was about to run out, an event that resonates with overtones of biblical punishment. Otto and her colleagues told the world that the climate crisis caused by the burning of fossil fuels had increased the likelihood of the drought by a factor of three. There was also the sizzling summer of 2017 in South Europe and the Mediterranean Basin, which included a heat wave that was dubbed “Lucifer.” The researchers found that, thanks to human activity, the likelihood that a summer of that kind would repeat itself increased 10-fold.

And what about the huge forest fires that raged in Australia at the end of 2019? The researchers of World Weather Attribution found that human beings had increased by a multiple of four the likelihood that they will take place again.

“Climate change is not causing extreme events in a yes or no way – because all extreme weather events have multiple causes,” Otto explains. “But it does cause a heat wave in exactly the same way that smoking causes cancer. It’s not guaranteed you’re going to get cancer and you could get it without the smoking, but…,” she says, leaving the conclusion of the sentence hanging in the air.

Otto is also behind a study published in Nature in 2017, in which she and her co-authors pointed to the historical responsibility of specific countries for specific extreme weather events. The study examined a severe heat wave that struck Argentina in 2013, when temperatures climbed above 45 degrees Celsius (113 degrees Fahrenheit), a neglected electrical grid couldn’t cope with the load, and street demonstrations erupted. What did they find? “The historic emissions of the U.S. alone over the years made this heat wave in Argentina 34 percent more likely,” she relates.

Adopting Otto’s metaphor, we could say that this study showed that the United States stuffed cigarettes by force into Argentines’ lungs and increased their likelihood of becoming sick. By the same token, she maintains, it is possible to determine the scale of the contribution of the big oil companies to specific extreme weather events – the same companies that are investing such effort in trying to slow down action against the climate crisis.


“Well-founded numbers enable us to identify those actually responsible and expose attempts to conceal or even deny uncomfortable facts. Without numbers, the limits or responsibility become blurred,” she says.

NASA’s head climate scientist, Gavin Schmidt, who also heads the agency’s Goddard Institute for Space Studies, used the words “cutting edge” when he spoke to Haaretz about the work being done by Otto and her colleagues. He described the rapid-response attribution studies that she and her colleagues were conducting as being “both novel and interesting,” adding that, far from coming out of nowhere, “this is an extension of work that has been done for years.” He noted that “The real-time attribution from Dr. Otto is likely to be revised over time – but I think it is very likely to be correct ‘enough’ to be reported on.”

Similar views were voiced to Haaretz by Dr. Nikos Christidis, a senior climate scientist at the UK Meteorological Office and an expert on the field of attribution studies. World Weather Attribution’s rapid research uses established methods, he said, and is “an initial response to an event in time scales typical of the media. More detailed analyses need to follow to complete the picture.” Schmidt added, “One might think of it as ‘climate journalism,’ in the sense that ‘journalism is the first draft of history.’”

Petroleum giants like Exxon “knew that climate change was happening and that their business model was increasing the problem. They knew that people were dying because they were continuing to do what they did.”Dr. Friederike Otto

According to Schmidt, the climate crisis is at a point where it is possible to see the impact of human activity on heat waves, heavy rains, floods and droughts that are occurring with increasing frequency. “And yet most of the reporting on these events doesn’t mention this. If, along with the weather forecasts, people were told how much of the rain or heat intensity was our fault, that might bring home the seriousness of climate change in ways that we haven’t managed to date.”

In conversation, Otto explains the underlying idea of the method of attribution science. Simply put, it’s a comparison between the frequency of a particular event in the world as it is today, and the frequency of that same event in a world in which there was no climate crisis. When an exceptional event occurs, scientists must first define exactly what happened. Afterward they try to answer a question that sounds simple: What weather is possible in the world as it is today? This is the moment at which the immense knowledge that has been about the weather on Earth becomes concretely useful. Until a few years ago, there were too many holes in the database, but now the researchers can run and rerun computer models that enable them to determine the frequency of the event that was observed in reality.


At this stage the question arises regarding how different the results would have been without climate change. “Because we know very well how many greenhouse gases have been put into the atmosphere since the beginning of the Industrial Revolution,” Otto notes, “we can take them out of the atmosphere in the model.” The scientists run the computers again, and this time obtain the frequency of said event in an alternate world, the one in which humankind would wish to live. “Because the only thing that is different between those two sets of simulations are the greenhouse gases from the burning of fossil fuels, you can attribute the difference to climate change. So you can say that because of climate change, this heat wave that we just observed became 10 times more likely.”

In this way, the research teams were able to make a determination with regard to hundreds of extreme weather events that occurred in recent years, finding in the great majority of cases that human influence was present in a specific event. These are not futuristic scenarios that will affect generations yet to come – they are the here-and-now. “In basically every country in the world, heat waves are the extreme event that are becoming more by far the most likely,” Otto observes. “For heat waves, we see that they are becoming more likely in the most dramatic way, while everything else, if it changes at all, it’s more like doubling in its likelihood. Whereas for heat waves, the likelihood can be 10 or 100 times greater,” she explains, adding, “Adaptation is something we need to do now, no matter what happens with mitigation – this is something science can help emphasize. And for adaptation, the very first thing is to make sure that heat is a major priority.”

At the heart of the calculations carried out by the climatologists lie the models referred to by Otto. Each of them can be thought of as a computerized simulation of the planet, surrounded by a three-dimensional grid stretching from the ground to the atmosphere. Each grid creates thousands of cells, and each of them, down to the last one, is represented by a mathematical equation that describes the materials in the cell and the energy that passes through it.

The equations are based on the laws of physics, chemistry, and the movement of liquids. To run a model, scientists enter the climatic data, such as the quantity of greenhouse gases in the atmosphere, at which point powerful computers are activated that solve the equation in each cell. The results from of each cell are transferred to the neighboring cells, and the equations are solved again. When the process is done repeatedly, a representation of the changes across the planet over time is obtained.

The models used in climate calculations, however, can be so complicated that the only way to run them is with supercomputers – the computers that possess the most advanced calculation powers in the world, but to which access is both limited and costly. To run a model that represents one year, Otto explains, might require two weeks of computer time, and in her case, when a large number of models is needed to arrive at a high level of confidence in the results, waiting that long is out of the question. On this issue she writes, “Essentially, we are only able to do what we do because of a very special, adventurous community of people hunting for aliens in space.”


She is referring to the way that the University of California, Berkeley, solved a problem in the 1990s: how to scan a vast quantity of audio recordings from space made by radio telescopes, which require a human ear in order to be analyzed. The solution was to create software that distributes the recordings to volunteers worldwide, who listen to them and in so doing assist in the effort to locate intelligent life in outer space. The project of rapid weather attribution makes use of exactly the same software as at Berkeley, but in a slightly different way: Thousands of volunteers around the globe allow the software to use the available memory of their individual computers to perform climatic calculations, which together add up to a system of enormous calculating power. “It allowed us to run those really large ensembles of models,” Otto says of the project.

Empty green declarations

Near the end of November 2009, a story exploded in the international media that left climatologists with painful scars that still linger. The leaking of hundreds of emails that had been exchanged by members of the community, and, from which remarks of climate scientists were taken out of context, was intended to make it seem as though these scientists had conspired to deceive the public by deliberately exaggerating the implications of the climate crisis.

The report by the panel of scientists will serve as a significant basis for the discussions of the UN conference on climate later this year. Many view this event as humankind’s last chance to prevent a worse climate catastrophe.

The electronic correspondence was hacked from the server of the Climatic Research Unit of the University of East Anglia, in the U.K., and began appearing on the web shortly before the convening of the UN conference on climate change, held in Copenhagen that same year. One of the most important conferences internationally, the UN event was intended to motivate the countries of the world to take determined and decisive action in the face of the threat. But instead of inspiring change, the partial publication of correspondence that undermined the credibility of the science involved, weighed heavily on the meeting. For example, one of the climatologists who was compromised by the leak, Michael E. Mann, related that the Saudi delegation to the conference invoked details from the leaks in their attempt to try to dilute resolutions in the negotiations.

In the years since then, several different commissions of inquiry convened to examine meticulously the allegations against the scientists, according to which they were deliberately misleading the public. The conclusions reached were that their actions were impeccable. Yet even now, 12 years later, the identity of the hacker remains unknown. For many climate scientists, “Climategate,” as climate change deniers predictably labeled it, heightened the feeling that they are involved in a constant war, and Otto notes that in its wake, many scientists began censoring themselves. She herself, she says, belongs to the first generation of scientists who learned about the affair from news reports and the stories of veteran colleagues.

North America

Given this background, it’s understandable why Otto devotes considerable time to talking about campaigns of deception and the responsibility of the oil giants. The scientist who is focusing on closing the “causal chain” – from the emission of greenhouse gases to a deadly heat wave – says that petroleum giants like Exxon “have blood on their hands, primarily because of the active spread of disinformation. They knew that climate change was happening and that their business model was increasing the problem. They knew that people were dying because they were continuing to do what they did.”

That conclusion is based on numerous investigations conducted over the years that exposed the scope of the knowledge in the oil companies’ possession. For example, in 2015 the Inside Climate News site published a resounding series of investigative reports showing that by the 1970s at the latest, Exxon knew about the disastrous impact of its business model in the wake of internal research the company conducted.

Already in the 1970s one of the company’s senior scientists stated that “there is general scientific agreement that the most likely manner in which mankind is influencing the global climate is through carbon dioxide release from the burning of fossil fuels… There are some potentially catastrophic events that must be considered… Rainfall might get heavier in some regions and other places might turn to desert. Some countries would have their agriculture output reduced or destroyed. Man has a time window of five to 10 years before the need for hard decisions regarding changes in energy strategies might become critical. Once the effects are measurable, they might not be reversible.”

At the beginning of the 1980s, internal Exxon documents included a graph showing clearly the close connection between greenhouse-gas emissions and global warming, with a forecast for the future and additional information on the subject on the subject that revealed just how much the company understood about the problem even then. Did those documents change anything? Did the fact that the campaign of deception was exposed change the rules of the game? Just last June, a secretly recorded video of an Exxon lobbyist in Washington was revealed, from a sting operation of the Greenpeace organization’s investigative unit. The lobbyist relates how even today, the company is trying to interfere with the climate policy of U.S. President Joe Biden, and why its green declarations, too, are actually no more than a publicity stunt.

“There’s often that argument that we’re all responsible because we’re all using CO2 in our lifestyle,” Otto says. “But we don’t live this lifestyle because it’s the choice of individual people – it’s the choice of a country that is capable of making laws and providing infrastructure that are very different. And in the case of the big carbon majors, they are aggressively selling a business model. There are people who are more responsible [for our situation] than others. That’s not only an ethical argument – but you can actually show how it plays out in the science.”

At present, Otto is engaged in discussions with lawyers who are interested in taking the climate struggle into courtrooms, and only recently she published a study on the subject. “We looked at 80 climate litigation cases that were brought to court in the last few years,” she explains. “I looked at the scientific evidence in these cases and found a big discrepancy between what could have been said from a scientific point of view and what was actually presented in these cases as scientific evidence. So in fact, those cases could have been a lot stronger if the science presented was state of the art and not as it was 10 years ago. I think the potential exists for attribution to really make those cases a lot stronger. But for that to happen, the communication between the legal and scientific community needs to improve.”

What’s the next step? The report of the international panel of scientists just published, of which Otto is one of the lead authors, will serve as a significant basis for the discussions of the UN conference on the climate that will convene in Glasgow at the end of this year. Many view this conference as humankind’s last chance to prevent a worse climate catastrophe. But even if the meeting succeeds beyond expectations, and even if all the countries in the world live up to their promises, there is still no model in which climate events do not become ever more extreme over the decades ahead. And therefore, this leading scientist from Oxford says, now is the time to prepare.