An architect of the Paris climate agreement urged governments yesterday to halt oil exploration in the Arctic, saying drilling was not economical and warming threatened the environmentally fragile region.

Christiana Figueres, formerly head of the UN Climate Change Secretariat when the Paris accord was reached by almost 200 nations back in 2015, told Reuters by telephone “the Arctic has been rendered undrillable”.

The past three years have been the hottest since records began in the 19th century, and Figueres said the heat was a threat to everything from Australia’s Great Barrier Reef to ice in Antarctica.

The former Costa Rican diplomat who campaigns for a peak in global emissions by 2020 said it made no economic sense to explore in the Arctic, partly because it was likely to take years to develop any finds.

Capital investment would be better used developing renewable energies such as solar and wind to cut emissions, she said.

The Paris Agreement sets a goal of ending the fossil fuel era in the second half of this century. It has been weakened by a planned pullout by US President Donald Trump, who doubts mainstream scientific findings that global warming is man-made.

Many governments and companies favour Arctic drilling.

Last month, Trump’s administration began environmental reviews for oil and gas drilling in a section of the Arctic national Wildlife Refuge.

In Norway, Statoil and other companies plan to keep up exploration in the Arctic Barents Sea, which is ice-free further north than other parts of the Arctic thanks to the warm Gulf Stream.