The call comes after ministers admitted they will not decide how to fund a strategy to meet their legal commitment to achieve “net zero” carbon emissions until the end of the year.
This week, the health secretary issued a “carry on flying” message – and the climate crisis was barely mentioned by the prime minister during the election campaign, when he boycotted the Channel 4 debate on the issue.
Now the vice chair of the independent Committee on Climate Change has advised the prime minister that there is no more time to waste.
“We are not on track to meet existing legal targets for the 2020s and 2030s – and now we have raised the bar,” said Baroness Brown, revealing the contents of a recent letter.
And she added: “We would like to see the climate change Budget in March.”
The challenge comes ahead of the UK being thrust into the international spotlight when it hosts the United Nations COP26 climate change conference in Glasgow, in November.
Theresa May won plaudits for pushing through the legal duty to end the UK’s contributions to climate change by 2050 – but left the action plan to her successor.
But Mr Johnson’s only eye-catching pledge has been a plan to deliver zero-carbon energy from nuclear fusion by 2040 – even though experts believe achieving the dream is still 30 years away.
Speaking to BBC Radio 4, Baroness Brown suggested the measures the government should adopt, including:
* Accelerating the end of sales of petrol and diesel cars from 2040 to 2030;
* Tackling CO2 emissions from the 30 million buildings in the UK that still burn fossil fuels; and
* Helping farmers change land use to reduce the harmful impact on the planet – through the newly-published agriculture bill.
Baroness Brown said the Glasgow summit would be “absolutely crucial”, adding: “This is the meeting where countries will be raising their nationally determined contributions, their commitments, to reducing emissions by 2030.
“The UK, as chair of COP, has a hugely important opportunity to emphasise our world-leading commitment to net zero emissions.
“What we need to do, to have credibility as chair of COP, is not only have that target but to be demonstrating that we have the policies in place to deliver it.”
This week the last decade was confirmed as the hottest on record, according to three global agencies. Nasa, Noaa and the Met Office examined records back to 1850 and found the past five years had been the hottest.
The figures prompted Sir David Attenborough to warn: “The moment of crisis has come, we can no longer prevaricate.”
Speaking to the BBC on Thursday, Sir David said: “We have been putting things off year after year. We have been raising target and saying, ‘Oh well, if we do it within the next 20 years...’”
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