The prime minister admitted he “doesn’t really get” climate change, the former head of this year’s key summit on the issue has said.
The UK is hosting COP26 in Glasgow in November – but Boris Johnson sacked president Claire O’Neill on Friday.
Mrs O’Neill told the BBC there was a “huge lack of leadership and engagement” from the government.
But senior cabinet minister Michael Gove said Mr Johnson was dedicated to environmental issues.
Mr Gove told BBC Radio 5 Live that the prime minister described his political outlook as that of a “green Tory” when they first met 30 years ago.