The world needs to mount a “Covid-scale” investment worth hundreds of billions of pounds in green technologies if it is to tackle global warming, the head of Britain’s nuclear fusion programme has warned.

Professor Ian Chapman, who heads the UK Atomic Energy Authority (UKAEA), told the i newspaper that he believes nuclear fusion is viable but society “does not have its priorities right” when it comes to spending on green technologies.

He said global leaders have not yet fully grasped the urgency and importance of fully funding existing and emerging technologies such as fusion, carbon capture and next generation solar power to provide a full portfolio of green energy sources.