It gets awfully chilly when someone steals your clothes. The Liberal Democrats, who have a long tradition of advocating bold environmental policies, have got used to being left shivering outside in recent times as both Labour and the Conservatives battle for the title “Greenest Party in Britain”. But the fightback began in earnest this week, with Menzies Campbell announcing to the country that he and his party have a unique dream (for a mainstream political party, at least) of achieving a “zero-carbon Britain” by 2050.

What, you didn’t notice? Yesterday’s Guardian, for example, carried the news at the bottom of page eight (enveloped by an advert for cheap holidays abroad, no less), whereas it barely warranted a mention on the television news bulletins. It didn’t help that the Conservatives were already wise to the Liberal Democrats’ major policy announcement, because details had slipped out a week earlier. They were thus able to steal some of the Lib Dems’ thunder by simultaneously releasing details of their own new greened-up transport policy.

The Lib Dems’ proposals still need to be approved by party members at next month’s conference. But flicking through this vision of life in Britain if we were actually able to reduce carbon emission by 100% makes you realise quite how much political movement there has been on these issues in the past few years. Which mainstream party, after all, would have dared to talk about making it compulsory for cars to be free of carbon emissions by 2040, or establishing personal carbon allowances not just in Britain but across the world, or capping airport capacity at today’s levels? The Lib Dems’ policy document is about as bold as a mainstream party is likely to go in today’s political scene. But the political climate is changing almost as quickly as the planet’s. It is highly likely that, even if voters reject this vision in the short term, it will drag the other parties’ policies in the same direction. No one is likely to run on a ticket of “Let’s burn lots more of the black stuff” ever again.

But dreaming of such a future is the easy part. Is it really possible to achieve a zero- carbon Britain, given what we already know of our current lifestyle addictions - flying, driving, heating and shopping - and enslavement to an oil economy? And what would it be like to live in such a place? In essence, what the Lib Dems (and, to be fair, some of the more green-minded Conservative and Labour politicians) are proposing is that we move towards a so-called “pay as you burn” world. Every service or product we purchase - be it a mini-break, a television, or bottle of wine - would have its full carbon cost “internalised”, as economists like to say. If you have a taste for a carbon-rich lifestyle, you would be highly taxed accordingly. As a carrot to go with this stick, those choosing to live a “carbon-neutral” lifestyle would be rewarded with far lower taxes and other inducements. For example, the Lib Dems say they would encourage zero-carbon home building through initiatives such as cheaper “green mortgages”. Significantly, the Lib Dems say their green taxes (a term that, so far, the Conservatives dare not utter) would be “revenue neutral” too - rises in one area would be accompanied by cuts elsewhere.

But it’s not all about twiddling the dials of consumer choice. The country would need to make a massive shift towards low-carbon energy technologies instead of ones reliant on fossil fuels. The Lib Dems stress that they would not build a new generation of controversial - but some say essential - nuclear reactors. Instead, new research funding would encourage our universities and energy companies to further develop renewables, such as offshore wind and solar. The bulk of our energy would need to be generated locally, too, instead of being reliant on the hugely inefficient grid network. In fact, if you were looking for one word to sum up life in zero-carbon Britain, it would be “local”.

“Localism will become the buzzword,” says Mark Lynas, the environmentalist and author of Six Degrees: Our Future on a Hotter Planet. “It is technically possible to achieve a zero-carbon Britain by 2050 as we are blessed with abundant renewable resources, especially off-shore wind in the shallow North Sea - although it will be a harder task without nuclear, on which I am agnostic. This largely covers electricity generation, but weaning ourselves off fossil fuels for our transport needs is much harder to achieve. There will certainly be a reduction in the amount we travel as a result. Being less mobile will become a reality. But being mobile isn’t always a good thing, as we largely see it today. There are many co-benefits of being less mobile and less car-reliant. For example, children will be able to play on the streets once more.”

Lynas believes this will lead to a move away from the suburbanised living many of us experience today. “Most of us will not need to commute long distances to work any more [as new technology reduces the need for centralised offices, for example]. The supermarkets will also not be able to afford to operate today’s centralised distribution networks and food will be grown and sold much more locally as a result. More widely, culture values will change significantly. Conspicuous consumption will become socially embarrassing. We are already seeing this starting to happen with, for example, negative attitudes towards 4x4 drivers”.