Officials from almost 100 countries are at the International Court of Justice in the Netherlands, asking the court to issue an opinion on the responsibility of certain nations to protect the planet from climate change.

Representatives for the island nation of Vanuatu called on the International Court of Justice this week to recognize the harm caused by climate change, the first remarks the United Nations court heard as it considers international obligations to address climate impacts.

The International Court of Justice, the United Nations’ highest judicial body, is beginning landmark hearings on global warming. Here’s a guide.