Joss Garman: 'The gravest threat', yet the Punch and Judy show goes on

Like the ghost of progressive politics, Ed Miliband last week announced his ambitious plans to transform Britain into a low-carbon economy.

It was impressive stuff: it could generate hundreds of thousands of green jobs and £70bn for the British economy. It will reduce our dependence on foreign oil and gas, improving our national security, and, eventually, save householders money. So long as the carbon savings aren't wiped out by new coal and runways, his strategy will also slash Britain's emissions.

To be fair to the Conservatives, many of the ideas presented were flagged by them months ago, such as the plan to create low carbon economic zones around the country. Crucially, both main parties now agree that a huge boost in wind power will be the principal way to deliver in the short term and that more renewable heat and electricity should be generated in homes. They even both offer the same mechanism to deliver this – the "feed-in tariff" so successful in Germany. Both parties agree that it's vital to reform Ofgem, the energy regulator, to put cutting carbon at the heart of their mission, to speed up access to the grid for renewable projects and build a smarter, more efficient national grid.

Greg Clark, the shadow Climate Secretary, began well. "This is an area in which we should not pursue narrow, short-term partisanship, but where the long-term interests of the country must come first." Then he reverted to type. "But," he asked, "will the Secretary of State be candid in accepting that we start from a poor position? Over 12 years we have had 15 energy ministers, but no energy policy..." Why the inexorable push to create conflict where none exists? When discussion focuses on magnifying small differences over details and looks back for a point of contention, it seems the parties' chief aim is to find something to argue about.

In times of war or other major emergencies, when something really big needs to happen, it generally does. Political swords are sheathed for the greater good. In the 1990s, when Northern Ireland was seen as a deeply divisive ideological and political problem, progress towards a peace agreement was made when the political parties put aside their gamesmanship and built a rock-hard consensus.

Adversarial politics is a recipe for inaction. Each proposal will be keenly criticised, because that's Parliament's job, compromises pushed, costs and risks exaggerated and then scaled back, and change, which we all seem to fear so much, minimised. If stability is the main aim, adversarial politics is fine. But it's an absolute disaster during major crises, such as climate change, that require rapid and wide-reaching change.

There are political footballs, and there are national emergencies. Politicians like apocalyptic rhetoric, as they think it makes them sound important and statesmanlike. Our "leaders" say climate change is the gravest threat and defining issue of our times, but they are still booting it back and forth.

David Cameron is often accused of using the green agenda to decontaminate the Conservative brand. If he wants to show it's about more than party politics, this is his opportunity to prove it. He could stop his party blocking wind farms and back a Labour proposal that, at last, offers the prospect of real, on-the-ground green delivery. We urgently need all three main parties to come together and find a way to accelerate the change we're hoping for. Yes, they can. After all, they did it on expenses.

Joss Garman campaigns for Greenpeace and writes for The Ecologist