Climate models: the new frontline of climate justice?

Climate models – computer simulations designed to predict the future of the Earth’s climate – have long been used to predict the long term effects of climate change. But now these models are being used to link extreme weather and climate change, opening up the law as a new pathway for climate action and a powerful tool in the fight for climate justice. 

An unlikely frontier of climate justice 

Six miles outside the remote Peruvian city of Huaraz, high up in the mountains, sits a small, stone hut next to Lake Palcacocha. Here, the ‘Guardians of Palcacocha’, a group of local volunteers, watch day and night for signs that the glacier sat above the lake is about to collapse. Their concern is not with the glacier collapse itself, but rather that its smashing into the lake will trigger a massive flood.

This lake has previous: in 1941, one of these so-called glacial lake outburst floods led to devastation in the valley downstream, killing 1800 people and decimating most of Huaraz. And, as the climate warms, these events are expected to become more frequent. Combined with a 3400 percent increase in the volume of Lake Palcacocha, in just a couple of decades, it’s only a matter of time before another catastrophe. To prevent another disaster, intervention is required.

In 2011, the local authorities embarked on a massive siphoning project. Sucking the water out of the lake and diverting it elsewhere has lowered the level of the lake some 5 meters. But firmer defences are needed, and they don’t come cheap. 

This begs the question of who should pay. Saúl Luciano Lliuya, a farmer and mountain guide in from the neighbouring village of Nueva Florida, insists that it shouldn’t be the locals. Lliuya wants “los responsables” – those responsible for the risk to his family, livelihood and community – to foot the bill. And it makes sense: in so many other areas of life, if your actions put someone else at risk, you have to pay for their protection. Think protective equipment in a dangerous workplace: an employed must provide hard hats, high visibility clothing, steel toecapped boots.

That’s why Lliuya is suing an energy company – RWE – based some 10,000 kilometers away in Germany. Lliuya argues that, because RWE are responsible for about half a percent of climate changing fuelling emissions to have been emitted since the industrial revolution, they should pay half a percent of the cost of the defences, in this case around $19,000. 

Who is responsible?

The key hitch in Lliuya’s case is, ironically, his key claim: who is actually responsible for the glacier’s collapse? In legal terms, what is the tort – the wrongful act that results in the loss or harm. Climate change is in nature an ‘anti-tort’, it is a problem that is diffuse in both space and time. It is the accumulation of emissions which raises global temperatures: carbon dioxide emissions 100 years ago have basically the same climate warming effect as emissions today. And it’s global: the Earth’s atmosphere responds in the same way to emissions in Germany as it does to emissions in the Andes. 

So how can we link emissions in one place, at one time, with the present retreat of a specific glacier in the Peruvian Andes? Climate models can help to provide the missing evidentiary links. In the Lliuya vs RWE case, climate models have been used to show that greenhouse gas emissions have raised temperatures in the region, with a knock on effect on the glacier and thus the local flood risk rise. Using these models, they are able to conclude that greenhouse gas emissions have substantially increased the outburst flood hazard.

Polluters on trial

The climate uncertainty felt by those living in Huaraz is not unique. Around the world, communities increasingly feel the threat of extreme weather, which are becoming more common as the climate warms. The first months of 2024 alone have seen devastating floods in Pakistan and Afghanistan, raging wildfires in the Pacific Northwest of the United States, and severe drought in Southern Africa.

In the face of this growing uncertainty, people are increasingly turning to the law to demand governments and companies do more to tackle climate change and to seek compensation for the harms it causes. In 2023, Greta Thunberg and 600 other young activists sued the Swedish government, claiming it’s current actions breach the European Convention on Human Rights. Two years earlier, a group of teenagers led by an 86-year-old nun successfully sued the Australian government to prevent the approval of a coal mine on similar grounds (though this decision was later overturned on appeal).

Most climate litigation cases, such as these, are legal challenges to emissions reductions targets governments have set themselves. To many people, these can feel vague and distant. It’s hard to imagine our lives 25 years from now – in 2050 – the date at which many governments have set themselves to be carbon-neutral. Rather, people’s perceptions of the climate change are largely experienced through weather. Indeed, an increased push for climate action in the West has been linked to a perceived increase in extreme events. 

Attribution science: the link between weather and climate

The glacier upstream of Lake Palcacocha has, for centuries, lost icebergs. Even without climate change, this natural process would have occurred. But, climate change is thought to have accelerated it. It’s the same for extreme weather, and that’s the challenge of linking these to climate change. Even if there was no climate change, droughts, wildfires, and floods would occur. The difference is one of likelihood: how often is an extreme event expected to occur, and this is where climate models come in.

Perhaps surprisingly, the key is to consider what happens if there was no climate change. This is what scientists call a ‘counter-factual’ scenario. Comparing how often extreme events occur in the counter-factual scenario, with how often they occur when climate change is included in models, allows the role of climate change to be quantified. For example, if a drought like the 2024 southern African drought occurs 20 times in 100 years, on average, in climate models including climate change, and only 4 times in 100 years in the counterfactual scenarios, climate change can be said to have made such an event 5 times more likely. If an extreme event never occurs in the counterfactual scenarios, scientists may report that it was impossible without climate change.

This approach has proved controversial within the climate community. Critics argue that weather is weather and climate is climate, that we can’t compare across the vastly different timescales on which weather (days to weeks) and climate (centuries to decades). Others have criticised the research approaches: the World Weather Attribution initiative issues very rapid assessments of the role of climbing change, circumventing the traditional – extremely slow – peer review process in favour of hasty judgements (though, importantly, the methods they employ are peer-reviewed). This means that their judgements can be issued while the event in question is still in the news cycle, increasing the impact.

A new era for climate litigation – and climate justice?

The Lliuya case is an important test case. Should he be successful, it would set an extremely important significant legal precedent. It would undoubtedly pave the way for a deluge of extreme-event related lawsuits. However, there is still a way to go. Lliuya vs RWE has remained in legal quagmire for almost eight years now, suffering under COVID-related delays and the glacial pace of legal systems. 

Major emitters also won’t go down without a fight. A world in which loss and damage lawsuits can be brought against them, claiming for damages in the billions of dollars, poses an existential threat to them. RWE has publicly outlined arguments it might make in court, should the case proceed beyond its current discovery phase: that success for Lliuya would pave the way for a “war of everybody against everybody” in which anyone might be sued for flying in planes or driving in cars.

What captivates the attention of this case, beyond the David vs Goliath nature of it, is the sheer diversity of stakeholders involved in such a complex problem. It draws in climate scientists, activists, politicians, lawyers, anthropologists, and more. All must come together to provide a compelling chain of evidence linking emissions in one part of the world, to harms experienced in another. 

Regardless of the outcome of the case, we can expect climate science, and particularly attribution science, to become an increasingly important part of climate litigation – and the fight for climate justice – in the future. Many climate cases brought before courts at present are thrown out for providing insufficient evidence, even though the climate science supporting their claims is available. The trouble is not with the evidence itself, but the communication between scientists and those lawyers presenting it.

Despite the risks of losing, Lliuya remains optimistic. On a recent trip to Egypt, for the COP27 climate conference, he insisted that he will “continue fighting – so that our mountains back home don’t turn to desert too one day.” This is truly a fight for climate justice it is: a community, which has contributed little to the problem of climate change, seeking protection from its devastating effects. And climate models might just help him win.