Yesterday’s budget is far more than just bad news for the environment. I think it rips up more than two decades of careful, cautious progress on green politics.

Since the late 1980s, (and yes, that includes a previous Tory government) we have been edging toward some kind of political consensus: a growing agreement that, in order to sustain our economy and society, we need policies and a politics that values the environment. The Climate Change Act of 2008 was a milestone. For the first time, all political parties agreed a set of binding environmental limits, in the form of carbon targets – and pledged to reform the economy in order to meet them.

Of course, this progress has been too slow for many environmentalists, myself included. We have encouraged, cajoled, criticised and advised politicians in their search for green solutions. There have been steps back as well as steps forward –but the destination has been clear, regardless of the political colour of the government.

Until today.

Yesterday’s budget can only be seen as an all-out assault on the green consensus, carried out by the self-styled ‘greenest government ever’.

The reduction in fuel duty is top of my list of consensus-busting moves. Not because it makes motoring cheaper (it pales in comparison to recent rises in VAT and oil prices). But because it makes clear that the government thinks car use should be encouraged and car drivers protected. Yet road transport is responsible for a quarter of our carbon emissions, and massive transfers of public money from the poor to the rich, as this new SDC report shows. Making the case for alternatives to the car was always a difficult but necessary job; Osborne has made it many times harder now.

Second, the ambitions announced to relax planning policy, even auctioning prime sites to developers. The environmental and social implications of this are huge. Careful planning is the only way to build settlements that are walkable, with viable public transport. It is the only way to ensure socially mixed communities, which support local services and businesses. (More on this in my report and the excellent new book by Jon Reeds) Ironically, as Reeds points out, the US, having suffered the effects of decades of lax planning, is now moving in the other direction.

Then there’s the blow to zero-carbon homes. Buried deep in the budget documentation was a relaxation of the target that all new homes would be zero-carbon by 2016. WWF-UK, normally a bastion of polite reason, are outraged. Sure, it was a tough target – but government, industry and academics all agreed that stretch targets are the best way to drive innovation. Until now.

My last piece of evidence is rather more obscure: the removal of tax breaks for investment in renewables. Private investors can claim tax relief through the Enterprise Investment Scheme (EIS). (Full explanation here.) This scheme has been the backbone of wind energy co-operatives like Baywind. Until now. Investments in renewable energy no longer qualify. You can make money or you can be green, but not both. That would be greedy.

There’s lots more to the budget, including a Green Investment Bank that can’t borrow – see the BBC’s analysis here.

But looking at the package in its totality, there are only two conclusions that can be drawn. Either, that the coalition government has so little understanding of the policies necessary to build a green economy, that they have introduced policies with massive unintended consequences. Or, that they have purposefully unleashed an all-out attack on the green consensus, despite the reams of evidence that underpin it. I’m hoping beyond hope that it’s the former.