"People fleeing immediate danger due to the climate crisis cannot be forced to return home, the UN has said.
The landmark ruling centres on the case of Ioane Teitiota, whose home - the Pacific Island of Kiribati - is threatened by rising sea levels.
Mr Teitiota applied for protection in New Zealand in 2013.
The UN rejected his claim, saying he wasn't in immediate danger, but the wording of its ruling allows others to claim asylum based on climate change.
Sending asylum seekers home when their lives are threatened by the climate crisis "may expose individuals to a violation of their rights" - specifically, it said, their right to life."