They have come to Marrakech to work on the nuts and bolts of the Paris Climate Agreement.
However the election of Mr Trump now poses something of a threat to the deal signed less than a year ago in the French capital.
The treaty commits governments to take action to keep global temperatures from rising by 2C above pre-industrial levels and to do their best to keep that rise to less than 1.5 degrees.
But Mr Trump has promised that within 100 days of taking office he would "cancel" the agreement and "stop all payments of US tax dollars to UN global warming programmes".
Aware of Mr Trump's intentions, countries speedily ratified the Paris deal and it became a binding part of international law on 4 November.