The International Court of Justice (ICJ) began its first hearings on Monday to clarify what countries are legally required to do to combat climate change and help vulnerable nations fight its devastating impact.

It is the largest case in the world court's 80-year history. It will hear from 99 countries and more than a dozen intergovernmental organizations over two weeks.

The outcome of the hearings could result in grounds for establishing legal obligations worldwide.

Over two weeks, Vanuatu and other low-lying at-risk islands in the Pacific Ocean will spearhead the hearing.

"We want the court to confirm that the conduct that has wrecked the climate is unlawful," Margaretha Wewerinke-Singh, who leads Vanuatu's legal team, told the Associated Press.

"We find ourselves on the front lines of a crisis we did not create, a crisis that threatens our very existence," Ralph Regenvanu, Vanuatu's special envoy for climate change and the environment, told the court as proceedings got underway.

The hearings came a week after COP29, when wealthy nations agreed to provide $300 billion per year in climate finance for developing nations — an outcome critics slammed as inadequate.

The hearings will continue until December 13. The court's opinion is expected to be delivered in 2025.

Why is climate change being discussed at the ICJ?

For years, small island nations lobbied to get the UN General Assembly to ask the International Court of Justice last year for an opinion on "the obligations of States in respect of climate change."

"We are on the frontline of climate change impact," Vanuatu's climate envoy Ralph Regenvanu said.

"Our call for an advisory opinion from the ICJ on climate change is at a pivotal moment... one that sets clear the international legal obligations for climate action."

While activists are hopeful the outcome of the hearings will have far-reaching legal implications for violators others are sceptical given that the UN's highest court might take even years to deliver.

Any decision will be non-binding because the court has no concrete means to enforce its rulings.

mfi/zc (AFP, AP, Reuters)