The Paris climate accord negotiated last year has been ratified by enough countries for it to go into force.

A group of European nations raised support for the Paris Climate Change Agreement to countries that represent 56.75 per cent of world greenhouse gas emissions, above the 55 per cent needed for implementation.

Mr Trump said during his campaign he would withdraw from the Paris accord, ushered in by his predecessor Barack Obama. Credit:AP

​Germany, France, Austria, Hungary, Slovakia and Malta - European Union nations that have completed domestic ratification and account for about 4 per cent of emissions - formally signed up on Wednesday.

In total, 72 countries out of 195 have ratified the agreement, the UN said.