For the last two years the "transition movement" has been a grassroots effort by thousands of ordinary people determined to begin the transformation towards a low-carbon lifestyle. Today it became government policy. Not for nothing is Ed Miliband's green road map called the UK Low Carbon Transition Plan. No longer are towns and villages like Transition Lewes – or my own community effort, Low Carbon Wolvercote – on their own. Their demand – to be part of the low-carbon solution, rather than the problem – has been adopted wholesale by government.

Since the Climate Change Act was passed last year, the UK has theoretically been committed to an 80% reduction in carbon emissions by 2050. But that act was only half the battle won: the government still seemed to lack a strategic plan to actually meet the targets. Indeed, many government policies – on building roads, expanding airports and so on – seemed to take us in the wrong direction.

Miliband's white paper changes all that: the emissions reductions from each sector of the economy are quantified, and the policies to make them a reality spelt out. The paper sets out, for example, how each government department will be expected to stay within its carbon budget, outlines plans for a five-fold expansion of renewable electricity generation by 2020, increases the commitment to a new generation of nuclear power stations and brings forward measures to speed up the introduction of electric cars. There are three carbon budgets now in planning, each covering a five-year period, and running up until 2022, by which time emissions should have been reduced by a third from 1990 levels.

The plan isn't perfect, but it should give a new dynamism to the UK's efforts to reduce greenhouse gas emissions – something that has been sorely lacking until now. As if to illustrate the new sense of urgency, the Department for Energy and Climate Change has pledged to reduce its own emissions by a remarkable 10% by the end of 2010. The budgets are important in particular because they are legally binding: indeed, the UK is the first country in the world to enshrine its carbon targets in law.

There are plenty of areas of controversy. Wind power remains controversial, and a massive expansion of onshore wind can be expected to meet with major opposition – not least from Tories in the shires. Plans for a Severn Barrage are also being narrowed down, much to the concern of conservationists worried about the local ecological impacts. Nuclear is a perennially thorny issue. But all these areas will benefit from a streamlining of the planning system, which aims to speed up new-build projects of national significance.

Another plus point is that the government plans to eschew carbon offsets from abroad, making all the cuts domestically – at least in the first five years. (This doesn't include big corporate emitters, which can already buy and sell credits within Europe via the EU emissions trading scheme.) The plan also has a strong emphasis on one of the less sexy areas of emissions reduction: from the farming sector, where fertiliser use, land management and livestock add up to 7% of our national emissions.

Now it's over to us. The original Transition movement provided a DIY action plan for how we could all – as individuals, communities and regions – do our fair share while the government dawdled. Now the government has weighed in with a sensible national strategy, there can be no excuses about "waiting for the politicians to act". We are all responsible for reducing the threat our lifestyles pose to life on Earth – and we have to start now.