Leading article: Battle for the green high ground

It was illuminating that the Conservatives felt they had to leak something of their plans on the environment yesterday. The move was a blatant attempt to steal the thunder of the Liberal Democrats, who were launching detailed proposals to make Britain a carbon-neutral state by 2050, underlining a long-standing commitment to the environment. Despite this display of crude politics, there are good ideas in the leaked plans drawn up by the Tory policy group, chaired by John Gummer and Zac Goldsmith. It offers serious measures, for instance, to halt the growth in flights from Britain's airports, including a moratorium on all airport expansion. This is sensible, as is the imposition of VAT on fuel for domestic flights and taxes to ensure that planes do not fly half-full and to persuade travellers to switch from domestic flights to trains.

But the key question is whether these leaked ideas go any further. They may not make it into the final proposals. And even if they do, David Cameron is not obliged to adopt them. He has already indicated that he will drop his previous "green air miles" scheme – which at least had the virtue of not penalising the less well-off and indulging the rich. The Tories' big idea that their green taxes can raise money to fund tax breaks for married couples is unconvincing.

The Government will dismiss the Tory leak as an attempt to grab headlines about air travel which makes up less than 7 per cent of the UK's carbon emissions. Gordon Brown will argue that the real challenge is reaching an international agreement on a post-Kyoto framework. The idea here is for market mechanisms like carbon-trading to bind the world's major polluters – the US, India and China, which is building 70 airports a year – into a deal. The drawback is that while Britain has made some progress on this by persuading the EU to commit itself to a 20 per cent target for renewables and to cut emissions by 20 per cent by 2020, there are valid question marks over this government's desire to push through real change at home

Yesterday's proposals by the Liberal Democrats highlight how much more there is to do. They have proposed taxes on pollution not people and the introduction of green mortgages. They suggest a vastly improved new North-South high-speed rail line, paid for by road tolls, and a massive boost to Britain's flood defences. They propose a new fund to back clean energy in developing countries. Gordon Brown won few friends in the green movement during his decade in the Treasury. Now he is facing a real challenge to prove that he genuinely cares about the environment, and that his fine words on the subject are more than hot air.