MPs and the heads of environmental organisations have written to Theresa May saying the Budget presented to parliament on Monday is an “unforgivable betrayal of future generations”, due to its “worrying lack” of policy to combat climate change.

Green Party co-leader Caroline Lucas and six other MPs, including Labour’s Clive Lewis and former Lib Dem leader Tim Farron signed the letter, which says “pushing policymaking into the long grass of Brexit at this stage represents an abject failure to govern in the interests of the people you are elected to serve.”

The chief executives of Greenpeace, 10:10 Climate Action and Global Witness were also among the signatories, who said the Budget was “a nadir for this government’s tainted climate record” and demanded “urgent action in the coming days must be announced”.

“Not only did the chancellor fail to mention climate change in his speech, but the policies he put forward – from subsidy to polluters via the fuel duty freeze to a mass road building programme – will increase the UK’s climate impact,” the letter says.

It also takes issue with the government’s fracking programme and highlights the findings of the IPCC (Intergovernmental Panel on Climate Change) commissioned by the United Nations, published three weeks ago and which issued the most urgent and far-reaching call yet for world governments to cut their greenhouse gas emissions and stop global warming.

“[The report] was very clear about what governments need to urgently do – yet your government has all but ignored its publication in this Budget,” the letter says.

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Mr Hammond’s Budget included £28.8 billion for the National Roads Fund for Highways England between 2020 and 2025, an extra £420m on top of the current fund of £300m immediately available to councils to tackle potholes, and fuel duty has been frozen for the ninth consecutive year, despite the fact it was revealed freezing fuel duty costs the Treasury £800m a year.

The chancellor also killed off plans for a “latte levy”, which would have taxed disposable coffee cups.

The only green initiative announced was £60m towards planting trees – 500 times less than the sum going towards roads.

Here is the letter to the prime minister in full:

Dear Prime Minister,

On Monday, your Government presented its Budget, and in doing so revealed a profoundly worrying lack of policy changes to combat the greatest threat of our time: climate change. Not only did the Chancellor fail to mention climate change in his speech, but the policies he put forward – from subsidy to polluters via the fuel duty freeze to a mass road building programme – will increase the UK’s climate impact.

With fracking now proceeding, and continued tax breaks being handed out to fossil fuel firms, we believe it is now vital we call out failure from a generation of politicians who will not live to see the devastation that their policies will wreak on future generations.

The most recent IPCC report was very clear about what Governments need to urgently do – yet your Government has all but ignored its publication in this Budget. We should be very clear here about timescales. It’s almost too late already, so pushing policymaking into the long grass of Brexit at this stage represents an abject failure to govern in the interests of the people you are elected to serve.

We do not accept that individuals in the Government do not care about climate change, nor that it’s too late to change course. We simply state here and now that the Budget must be a nadir for this Government’s tainted climate record – and that urgent action in the coming days must be announced. Anything short of that would be an unforgivable betrayal of future generations.

Caroline Lucas MP

Clive Lewis MP

Liz Saville-Roberts MP

Anna McMorrin MP

Tim Farron MP

Alex Sobel MP

Roger Godsiff MP

Gillian Caldwell, CEO, Global Witness

John Sauven, Director, Greenpeace

Hugo Tagholm, Director, Surfers Against Sewage

Guppi Bola, Director, Medact