Climate litigant Nathan Baring speaks during a Senate Climate Change Task Force meeting in Washington DC in September.Credit: Mark Wilson/Getty

Twenty-year-old Nathan Baring is a third-generation Alaskan. Within his lifetime, he has seen winters shorten, cod fisheries collapse and cultural traditions suffer. He grieves for an Arctic that is disappearing before his eyes. “There is a very distinct loss of place here,” he says.

Baring decided to take action. He is one of 21 young plaintiffs who, in 2015, filed a lawsuit seeking to force the US government to reduce greenhouse-gas emissions. A federal appeals court dismissed the case, known as Juliana v. United States, in January.

But other attempts to fight climate change in the courts have been more successful. This week, the UK Court of Appeal blocked plans to build a third runway at Heathrow Airport, saying that allowing the expansion would violate the country’s obligations to the Paris climate agreement.

Such decisions are inspiring and instructing activists and municipalities around the world as they attempt to force action against climate change. As litigants fight scores of such cases, recent rulings such as these make one thing clear. “There is no silver litigation bullet for climate change,” says Michael Gerrard, director of the Sabin Center for Climate Change Law at Columbia University in New York.

On 18 February, the International Bar Association released a model for how to litigate climate change, laying out legal arguments and precedents that might help future plaintiffs. What is likely to succeed seems to vary around the world, however — and as plaintiffs learn from their experiences in the courts, they are adjusting their tactics. The Heathrow case is the first major ruling based on the Paris agreement and could spur more suits that rely on those obligations. In other parts of the world, plaintiffs are increasingly focusing on seeking damages from polluters themselves.

A matter of trust

The Juliana case is one of more than two dozen cases that have been brought around the world on the basis of ‘public trust’ arguments, which say that the state has a duty to protect public resources from harm. Such arguments are closely linked to the idea that the fundamental right to life is inextricably tied to a healthy environment. Although the US court found that the plaintiffs had been harmed by the government’s inaction on climate change, the judges ultimately ruled that it was not within the court’s power to legislate climate policy.

But outside the United States, the human-rights approach is the legal strategy that has had the most success so far in forcing governments’ hands, says John Knox, an expert on international environmental law at Wake Forest University in Winston-Salem, North Carolina. Suits based on these types of argument have been brought on every inhabited continent.

In Urgenda Foundation v. State of the Netherlands, a case brought by an environmental group and nearly 900 Dutch citizens in 2015, the Dutch supreme court mandated that the government achieve a 25% reduction in greenhouse-gas emissions from 1990 levels by the end of 2020 to protect its citizens from the harms of a warming climate system. And in Demanda Generaciones Futuras v. Minambiente, Colombia’s Supreme Court ordered the government to implement protective measures to halt deforestation in the Amazon — that case was brought by 25 young Colombians. Like Juliana, both cases rested on the idea that the right to life is endangered by threats to the environment. Their success suggests that we can expect to see more suits brought by citizens against their governments, says Knox. Meanwhile, climate activists are watching closely to see how these governments comply with the court-ordered actions.

Damage limitation

So why did Juliana fail where similar cases have succeeded? Its scope — asking the courts to force the US government to not only stop permitting and subsidizing fossil-fuel use, but to also implement a plan for reducing atmospheric carbon dioxide levels — meant it was “always going to be a long shot”, says Ann Carlson, who studies environmental law at the University of California, Los Angeles. The court was reluctant to make these sorts of complex policy decisions. And given the increasingly conservative makeup of many US federal courts, Carlson thinks it is unlikely that future cases based on similar arguments will succeed.

Instead, Gerrard and Carlson anticipate that US activists and municipalities will pivot from targeting governments to going after the producers of emissions themselves — a strategy seen as more pragmatic because it seeks to impose cash penalties, which can, in some cases, be used for climate-mitigation efforts.

At least a dozen cases in the United States are now taking this tack. In County of San Mateo v. Chevron Corp., several Californian cities and counties are seeking funds from major fossil-fuel corporations to fund infrastructure for sea-level-rise adaptation. Oral arguments in the latest appeal were heard on 5 February, but a ruling has yet to be handed down. And several other individuals and localities, including the state of Massachusetts, are currently suing ExxonMobil and other companies for allegedly deceiving consumers about the risks of fossil-fuel use.

Although these damage-seeking cases are most popular in the United States, similar arguments for compensation are beginning to be made elsewhere. In November 2015, a Peruvian farmer named Saúl Lliuya brought a case in German courts against the German utilities company RWE, the largest emitter of CO 2 in the European Union. Lliuya, who lives near a glacial lake, alleges that RWE’s emissions are partially responsible for the dangerously high water levels seen at the lake as nearby glaciers have melted. He is seeking 0.47% of the costs of flood-protection measures for his town, equal to RWE’s proportion of global CO 2 emissions from 1751 to 2010.

Saúl Lliuya’s approach to fighting climate change? Take it to the greenhouse-gas producers.Credit: Anthony Kwan/Getty

Although the case was initially dismissed, an appeals court has since ruled that Lliuya’s complaint was admissible, and the court has ordered the parties to submit expert evidence — the first time such a case has moved to the evidentiary stage. The case is “very interesting” in its approach, Gerrard says, and victory could spur similar lawsuits around the world.

Although the recent ruling in Juliana was disappointing for plaintiffs, they say that they are heartened by the court’s finding that they had been harmed by the government’s inaction on climate change. They are currently preparing to appeal the ruling, and are still optimistic about getting a chance to argue their case in front of a jury. “We have many paths forward,” Baring says. “This is certainly not the end of the road for us.”