The UN General Assembly took a major step towards urgent global climate action Wednesday as members adopted a resolution calling for the world body's top court to outline nations' legal obligations related to curbing warming.

Cheers rang out as the measure -- hailed as a victory for the climate justice movement which hopes it will increase pressure on polluting countries failing to address the global warming emergency -- was greenlighted by consensus.

Pushed for years by Vanuatu, a small archipelago whose future is threatened by rising sea levels, and by Pacific islander youth, the resolution asks the International Court of Justice (ICJ) to lay out nations' obligations for protecting Earth's climate, and the legal consequences they face if they don't.

"Together, you are making history," United Nations Secretary-General Antonio Guterres said, emphasizing that even if non-binding, an ICJ opinion "would assist the General Assembly, the UN and member states to take the bolder and stronger climate action that our world so desperately needs."

Ultimately co-sponsored by more than 130 member states, the resolution had been widely expected to be approved.

"Today we have witnessed a win for climate justice of epic proportions," said Vanuatu Prime Minister Ishmael Kalsakau, whose country was ravaged by two powerful cyclones earlier this month.

It is "a win for people and communities across the world that are at the frontlines of the climate crisis," said Lavetanalagi Seru, regional policy coordinator for the Pacific Islands Climate Action Network.

The government of Vanuatu started lobbying for the measure in 2021, after a campaign initiated by a group of students from a Fiji university in 2019.

The adoption comes at a critical moment days after the UN's IPCC panel of climate experts warned global average temperatures could reach 1.5 C above pre-industrial levels by 2030-2035, underlining the need for drastic action this decade.

While nations have no legal obligation under the 2015 Paris Agreement to meet emission reduction targets, the new resolution's backers hope other instruments, including the UN Convention on the Law of the Sea, could offer pathways for enforcement.

"This resolution centers human rights and intergenerational equity when addressing climate change -- two critical points that have been missing from much of the dominant discourse," Shaina Sadai of the Union for Concerned Scientists advocacy group told AFP.

Describing the new resolution as "the most important global move since the Paris Agreement feels accurate," Sadai said, adding it was a critical next step for lending guidance to "lawsuits being brought in courts around the world."

The adoption comes the same day cases opened before the European Court of Human Rights against France and Switzerland over alleged failings to protect the environment, marking the first time governments are in the court's dock for alleged climate change inaction.

Although ICJ opinions are not binding, they carry significant legal and moral weight, and are often taken into account by national courts.

Vanuatu and supporters hope the forthcoming ICJ opinion, expected in about two years, will encourage governments to accelerate their action.

The enthusiasm however is not universal.

"I see scenarios where this request would be counterproductive," Benoit Mayer, a specialist in international law at the Chinese University of Hong Kong, told AFP.