An economist dubbed the world’s most prolific climate change sceptic finally admitted global warming was the biggest threat to the world and called for a $112 billion fund to fight it.

Bjorn Lomborg previously accused scientists campaigners and the media of exaggerating the rate of global warming and argued that resources should be spent on more immediate crises such as fighting malaria and Aids.

In a new book to be published next month he calls for a $US100 billion fund to tackle the problem and admits climate change is “undoubtedly one of the chief concerns facing the world today” The Guardian newspaper reported.

Mr Lomborg and his fellow economists recommend pumping money into researching and developing clean energy sources such as wind and wave solar and nuclear power and more work on climate engineering ideas such as cloud whitening which reflects the sun’s heat back into the outer atmosphere.