London (CNN)There were few memorable moments at the COP26 climate conference in Glasgow earlier this month, but a video address by the foreign minister of Tuvalu, speaking in a suit while knee-deep in tropical waters, is a hard one to forget.
It was simple but strong message -- while negotiators made agreements to delay action, island nations in the Pacific such as Tuvalu are sinking in rising seas, and could be swallowed entirely as soon as the end of this century.
There are many opinions on whether COP26 was a success or failure. However, there's one thing that the most climate-vulnerable countries left utterly disappointed about -- there was no agreement to get wealthy nations, which are most responsible for the climate crisis, to pay compensation for the havoc that climate change is wreaking on the frontlines of the crisis. The much-anticipated summit did little for climate justice.
On Thursday morning, three young climate activists in the United Kingdom will challenge its High Court to hear a case in which they hope to turn that around. They are seeking to sue UK Prime Minister Boris Johnson -- as well as his treasurer, Rishi Sunak, and business chief, Kwasi Kwarteng -- over what they say is a failure to put real action behind the country's own net-zero emissions plan. They claim the leaders are violating not only of their right to life as British citizens, but also of their right to family life, which they argue includes their relatives abroad.
Their case was first filed in May but a court refused to hear it on several grounds, including questions over whether a UK court has any influence on the lives of people in other countries.
But the three activists -- Adetola Stephanie Onamade, Marina Tricks and Jerry Amokwandoh, who all in their 20s -- and the charity Plan B Earth are trying to challenge that entire concept. The activists have Nigerian and Trinidadian, Mexican, and Ghanaian heritage, respectively, and believe that historical emitters have a duty of care to people, such as their relatives, in the Global South.
"[The court] dismissed the idea that our family life included our family around the world, or our family back home," Amokwandoh told CNN. "And they were saying that your family can only be limited to the British isles. It's a colonial mindset."
Tricks said they are taking particular aim at fossil fuel projects in the pipeline, including a proposed coal mine in northwest England, which is under review, and the exploration of oil in the North Sea.
"We are ultimately being screwed over by the system, by this government, because of its funding of the climate crisis," Tricks said.
"It's actively financing extractivist projects that are contaminating our lands, our waters and our air."
Johnson's offices did not immediately respond to CNN's request for comment on the case and claims. The treasury directed CNN to Kwarteng's office, which said: "We do not comment on ongoing legal proceedings."
This kind of litigation is something the UK government, and many around the world, will have to get used to. In a separate case, a number of activists backed by a group called Paid to Pollute will take Johnson's administration to the High Court on December 8 to block state money flowing into new fossil fuel projects. The group points to billions of pounds that the UK government has spent on oil and gas subsidies since the Paris Agreement in 2015, which committed the world to try and limit global warming to 2 degrees Celsius, but preferably 1.5.
Globally, the number of climate change-related legal cases has more than doubled since 2015, according to the Grantham Research Institute on Climate Change and the Environment at the London School of Economics. Just over 800 cases were filed between 1986 and 2014, but more than 1,000 have been brought since the year the Paris Agreement was signed, according to its latest report published in July.
"We're seeing a lot of groups using the courts to try and advance climate action where there might be frustrations with the political processes," said Catherine Higham, coordinator of the Climate Change Laws of the World program at the Grantham Research Institute.
The cases were bringing a kind of "interplay" between court rulings and politics, she said. In a case brought by German youths to the country's Constitutional Court in April, for example, the court ruled that the government needed to boost its climate plans to fall in line with the goals of the Paris Agreement. That legal decision kicked off more political debate on climate and the government ended up boosting its plans beyond the court's order.
"We see plaintiffs using the courts to try and advance climate action, but also as a tool to push the boundaries of political debate," she said.
And major fossil fuel companies are being targeted by litigation too. A Dutch court in The Hague made a landmark ruling against oil giant Shell in May, ordering the company to slash its emissions by 45% by 2030, from 2019 levels, to be in line with the Paris Agreement. Shell is appealing the decision.
That ruling could be truly transformative. It would be very hard for a company such as Shell to reduce its emissions by 45% without transitioning a good deal of its oil to renewable or low-emissions energy sources.
Higham says the decision could pave the way for similar court rulings against other major emitters. A similar case against French oil giant Total is being heard in France.
"One of the ways in which the Shell case differs from others is that rather than looking at compensation, the court gave a forward-looking order about what Shell needs to do -- a declaration that what Shell is currently doing is insufficient," she said.
"While we can't say how other cases, like the one against Total, will ultimately conclude, there is a big possibility that that cases will result in similar judgments against many other companies, or at least, that there will be many more actions building on the foundation that was provided by the Shell case."
Science finally gets its say in court
Climate scientists have long bemoaned the huge gap between science and political action. But for a long time, they were also largely excluded from another arena of power -- the court system.
Today, courts are increasingly considering science in their climate-related rulings, according to Bill Hare, a senior scientist and CEO of the think tank Climate Analytics.
"Courts are looking at what the science is saying, they're given more and more weight to reports by the Intergovernmental Panel on Climate Change (IPCC)," Hare said, referring to the landmark UN climate science report published every six to seven years. The most recent one was published in August amid a wave of extreme weather events across the Northern Hemisphere.
"There is still a huge gap between what countries are putting forward in terms of emissions pledges and what's needed, according to the IPCC science, so that's another dimension to this that the courts will look at," Hare said.
"I think that's something that's going to be very testing on governments. We've seen that already in the last 12 to 24 months and it can only grow."
Climate scientists are increasingly being called upon to share their expertise in courts of law, and as they get better at being able to make clear links between countries' and companies' emissions and their impacts -- like heatwaves or wildfires -- big emitters have less room to hide. This is even happening in transboundary cases.
One example is a case by an Austrian activists group called AllRise against Brazilian President Jair Bolsonaro. The group is petitioning the International Criminal Court to hear the case, in which they say Bolsonaro's policies that allowed for the rapid deforestation of the Amazon released emissions that contributed to climate change, causing deaths and real losses and damages to people's livelihoods.
Scientists were able to put an estimate on how much carbon dioxide and methane was emitted from those policies and found it accounted for around 1% of the world's global greenhouse gases each year. That's around the same as the UK's total emissions, they wrote in an expert submission to the case.
They also found that the amount emitted would lead to more than 180,000 excess heat-related deaths globally before 2100. That's even if global emissions are cut substantially.
"Climate change kills people. And the politics of Bolsonaro not only increases emissions, they increases the intensity of heatwaves, and that affects lives of people around the world, and, of course, locally, it's destroying livelihoods," said Friederike Otto from the Imperial College of London's Grantham Institute, who was among the scientists behind the written submission for the case.
"This kind of environmental destruction, on such a level, you should count as a crime against humanity because it destroys livelihoods on a large scale."
The Bolsonaro administration did not immediately reply to CNN's request for comment.
Otto also leads the World Weather Attribution project, which is one a group of scientists who use modeling and data analysis to estimate just how much climate change contributed to an extreme weather event.
This kind of science is useful in tort law cases, when a court needs to asses a civil wrong that has caused loss or damage.
"I think it's also important in the Bolsonaro example, because you can't hide behind generics anymore," Otto said. "It's not some vague future generation that will suffer. It's concrete people here that are losing their livelihoods and concrete dollars that someone had to pay."
The Bolsonaro case is truly unique in that litigating internationally on climate issues is difficult. There is no dedicated international court for climate crimes, for example, and even the ICC has its limitations. It can be constrained by its own power politics and some countries have refused to cooperate in cases that implicate them.
ClientEarth, a non-profit organization that provides legal services and advice in climate cases, has had several successes, including a 2020 case that led to Poland halting the construction of a coal plant.
A lawyer for the group, Sophie Marjanac, told CNN that COP26's failure to set up a scheme to pay compensation for climate impacts was "no less than a betrayal."
"Climate change is inherently unequal: its impacts -- such as droughts, heatwaves flooding, and rising seas -- are felt most in those countries least responsible. This is clearly a human rights issue," she said.
"When governments do not take action, litigation will increasingly be used to hold them accountable."