Courts around the world are hearing an ever-growing number of climate change lawsuits with some of the largest cases in history being decided in 2024 and 2025.
Here are the key cases to watch:
INTERNATIONAL COURT OF JUSTICE (ICJ)
The world's highest court is expected to issue a decision next year that will lay out U.N. member states' obligations in addressing climate change.
The U.N. General Assembly asked the court last year to come up with an advisory opinion, following a four-year campaign by Vanuatu, a small Pacific island nation where a group of law students initially dreamed up the ICJ petition.
With scant precedent on climate change in international law, the ICJ opinion could draw on arguments from past regional and national court rulings.
Even a relatively conservative ruling asserting that one country's emissions can harm another country could constitute a major victory for poor nations asking rich countries to pay more for climate action.
INTER-AMERICAN COURT OF HUMAN RIGHTS (IACHR)
The climate case before the Inter-American Court is shaping up to be the largest climate case to date, drawing on 262 submitted legal briefs, more than 600 participants, and hearings in both Barbados and Brazil.
Considered one of the world's more progressive courts, the IACHR could go further than its peers to set new legal rules and standards relating to national obligations around climate change.
For example, the judges' advisory opinion could address special protections for environmental defenders facing violence, name fossil fuels specifically as a key culprit in climate change, or oblige states to regulate polluting companies.
The court's opinion is expected by the end of the year, and will immediately apply to its 20 member countries in Latin America and the Caribbean.
INTERNATIONAL TRIBUNAL FOR THE LAW OF THE SEA (ITLOS)
On Tuesday, the international ocean court ruled that greenhouse gas emissions absorbed by the ocean are a form of marine pollution, subject to international controls.
A representative for the small-island nations that brought the case hailed the decision as giving teeth to global climate change law.
The court said that states are legally obligated to take all measures necessary to limit the rise in the average global temperature rise to within 1.5 degrees Celsius of pre-industrial levels, the target set in the 2015 Paris Agreement.
Countries are obliged to protect marine environments, even if they must go beyond the Paris requirements to do so, the court said.
EUROPEAN COURT OF HUMAN RIGHTS (ECtHR)
The European Court ruled in April that Switzerland had violated a group of 2,000 senior women's rights by not doing enough to combat climate change.
Unlike the other multilateral courts that are issuing advisory opinions, the European court case was a contentious lawsuit with a legally binding ruling that orders Switzerland to revise its climate policies.
The case establishes legal precedent for 46 countries that are signatories of the European Convention on Human Rights.
The European Court has seven similar cases on the docket including two that would directly impact Norway's oil industry.
SOUTH KOREA CONSTITUTIONAL COURT
Asia's first climate-related lawsuit in a national court joins together five different petitions into one megacase arguing that South Korea failed to protect more than 200 people from climate change.
The petitioners include young activists, children, infants and one individual who was a foetus at the time of legal filing.
AUSTRALIA: TORRES STRAIT ISLANDER CLASS ACTION
An Australian federal court is hearing the first class action lawsuit brought by Australian First Nations people, arguing the state has failed to protect them from climate change.
The plaintiffs live on the remote islands of Boigu and Saibai in the Torres Strait between Australia and Papua New Guinea. They argue that the country's inaction on climate change means rising sea levels will destroy their homes and eventually lead to the disappearance of their islands under the waves.
