Last month, the Climate Change Committee delivered a withering verdict on the government’s failure to come up with a proper plan to deliver on its admirably ambitious net zero targets. As the committee released two dismal progress reports, which showed Britain behind on its goal of a 78% cut to greenhouse gases by 2035, its chairman, Lord Deben, observed: “The policy is just not there. It’s clear we need to step up very rapidly.”

On Wednesday, ministers were at it again. As they contemplate a societal transition on an epochal scale, affecting all aspects of people’s everyday lives, Boris Johnson and his ministers appear to believe they can get by through a combination of setting dates and making heroic technological assumptions. This time it was the turn of the transport minister, Grant Shapps, to unveil eye-catching net zero pledges. According to the government’s delayed transport decarbonisation plan, polluting diesel and petrol lorries are to be banned in Britain by 2040 at the latest, and all types of transport will be decarbonised by 2050. Yet as the Road Haulage Association pointed out, zero-emissions heavy goods vehicles are still an aspiration rather than a reality, and Mr Shapps has delivered no detail on how the bill for this hypothetical transition will be met. In aviation, where the government has pledged net zero internal UK flights by 2040, there is a similar gap between rhetoric and reality. The notion that hydrogen aircraft and sustainable aviation fuels can obviate the need to fly less, at least in the medium term, is fanciful.

This airy techno-optimism costs nothing, of course, which suits the chancellor, Rishi Sunak, and means ministers can put off hard choices. But if the country is to even come close to net zero in 2050, they must get real and back up these aspirations with serious cash and a national plan. Homes, workplaces and everyday transport options need to be transformed. This will mean a mass mobilisation for which the government must be prepared to shoulder the financial burden, especially in relation to the less well-off. An architecture of green grants, subsidies and incentives must be introduced to remove financial obstacles for people who wish to do the right thing, but worry about the cost that will be incurred. In an AA poll last month, for example, two-thirds of respondents said that scrapping the 20% VAT on electric vehicles would be the quickest way to phase out petrol and diesel cars.

A more realistic route to net zero was outlined on Wednesday in a report published by the IPPR-led environmental justice commission, after a two-year consultation with citizens’ juries, business leaders and trade unions. The cross-party commission, co-chaired by the Labour MP and former environment secretary Hilary Benn, calls for an extra GBP30bn of public investment in a low-carbon economy each year until 2030. Among the report’s 100 recommendations are a GBP7.5bn green subsidy scheme promoting zero-carbon alternatives on home heating and insulation; redistribution of carbon tax revenues to the less well-off; free bus travel by 2025; and a right to retrain for workers in carbon-intensive industries. With the right levels of investment and support from government, its authors suggest, the transition to a low emissions economy can help create a fairer Britain as well as a greener one. Without ambition and imagination on this scale, the government’s “world-leading” green pledges will look like empty promises that were never intended to be kept.