The International Court of Justice called global warming an “urgent and existential threat” at a closely watched case in The Hague.

In a sweeping decision the UN's top court on Wednesday ruled climate change an "existential problem of planetary proportions" and said countries had a legal duty to act or face consequences.

The United Nations' highest court on Wednesday said countries must address the "urgent and existential threat" of climate change by cooperating to curb emissions, as it delivered an opinion set to determine future environmental litigation.