Washington DC [US], July 24: A landmark decision by a top UN court has cleared the way for countries to sue each other over climate change, including over historic emissions of planet-warming gases.
But the judge at the International Court of Justice in the Hague, Netherlands on Wednesday said that untangling who caused which part of climate change could be difficult.
The ruling is non-binding but legal experts say it could have wide-ranging consequences.
It will be seen as a victory for countries that are very vulnerable to climate change, who came to court after feeling frustrated about lack of global progress in tackling the problem.
The unprecedented case at the International Court of Justice (ICJ) was the brainchild of a group of young law students from low-lying Pacific islands on the frontlines of climate change, who came up with the idea in 2019.
One of those students, Siosiua Veikune from Tonga, was in the Hague to hear the decision.
"I'm lost for words. This is so exciting. There's a ton of emotions rushing through us. This is a win we take proudly back home to our communities," he told BBC News.
"Tonight I'll sleep easier. The ICJ has recognised what we have lived through - our suffering, our resilience and our right to our future," said Flora Vano, from the Pacific Island Vanuatu, which is considered the country most vulnerable to extreme weather globally.
"This is a victory not just for us but for every frontline community fighting to be heard."
The ICJ is considered the world's highest court and it has global jurisdiction. Lawyers have told BBC News that the opinion could be used as early as next week, including in national courts outside of the ICJ.
Campaigners and climate lawyers hope the landmark decision will now pave the way for compensation from countries that have historically burned the most fossil fuels and are therefore the most responsible for global warming.
Many poorer countries had backed the case out of frustration, claiming that developed nations are failing to keep existing promises to tackle the growing problem.
But developed countries, including the UK, argued that existing climate agreements, including the landmark UN Paris deal of 2015, are sufficient and no further legal obligations should be imposed.
On Wednesday the court rejected that argument.
Judge Iwasawa Yuji also said that if countries do not develop the most ambitious possible plans to tackle climate change this would constitute a breach of their promises in the Paris Agreement.
He added that broader international law applies, which means that countries which are not signed up to the Paris Agreement - or want to leave, like the US - are still required to protect the environment, including the climate system.
The court's opinion is advisory, but previous ICJ decisions have been implemented by governments, including when the UK agreed to hand back the Chagos Islands to Mauritius last year.
"The ruling is a watershed legal moment," said Joie Chowdhury, Senior Attorney at the Centre for International Environmental Law (CIEL).
"With today's authoritative historic ruling, the International Court of Justice has broken with business-as-usual and delivered a historic affirmation: those suffering the impacts of climate devastation have a right to remedy for climate harm, including through compensation," she added.
The BBC has contacted the UK Government for comment.
When asked about the decision, a White House spokesperson told BBC News:
"As always, President Trump and the entire Administration is committed to putting America first and prioritising the interests of everyday Americans."
Source: Fijian Broadcasting Corporation
