Nick Clegg: Eco politics for the real world

A vote for the Green Party would be a wasted vote, as only one party has both the will and the power to tackle climate change

The threat of climate change rivals any the modern world has faced. No challenge for our generation is greater than averting a climate catastrophe. The best predictions science offers suggest that, if the planet warms by more than C, it will tip us into the nightmare scenario of climate chaos we cannot control. It will affect not only the world's prosperity, but also our very ability to feed ourselves, threatening resource wars and mass migration on an unprecedented scale.

Time is of the essence in taking on this enormous threat. Campaigners and scientists alike are now clear: the next government is the last government that will be able to act. If the government chosen in next year's election doesn't take the action necessary to change the way Britain uses energy, it will probably be too late. That means next year's election is our best chance – probably our last chance – to get a government that will protect our planet for our children.

This is not a time for people who care about the environment to quarrel between ourselves. This is a time for unity. That's why, today, I'm launching a direct appeal to everyone who's ever voted for the Green Party, or is thinking about doing so at the next election. I'm asking you to lend your vote to the Liberal Democrats in 2010 to stop climate change. There is more information at the appeal website I'm launching today, One Planet, One Voice, which you can find at www.nickclegg.com/ oneplanet.

I understand completely why people are drawn to the Green Party. Lots of people explain it to me like this: they know the Greens can't win, but they want to send a message that the environment matters. I understand that. But the time for sending messages is over. It's time for action. Only a party with real power and influence at local, national and European level can make the radical difference needed.

There has been too much hot air from Labour and the Conservatives. Carbon dioxide emissions are higher now than when Labour came to power 10 years ago. And for all their green talk, the Conservatives are not committed to the tough action necessary. They oppose a new runway at Heathrow, but want to build new airports in the South-east instead. That's just hypocrisy.

If either Labour or the Conservatives are given a free rein in the next Parliament, they will fall short of what's needed. They will kowtow to business interests and political pressure. We cannot afford to let that happen, because if it does, it will be too late to act. And the Green Party, despite its good intentions, isn't strong enough to have an influence on the next government, let alone be the next government. They don't have a single representative at Westminster, or run a single council.

That's where the Liberal Democrats come in. We can make the difference. Already, there are 134 Liberal Democrat MPs and peers in Parliament. Our 11 MEPs are part of the third-largest grouping in the European Parliament. And our 4,400 local councillors have enormous influence over what happens in their areas. Liberal Democrats now control 64 councils, including the majority of big cities outside London. And we're making use of the power voters have given us to make the difference for our climate and the natural environment.

In Parliament, our votes got a "feed in tariff" put into law to encourage renewable energy; forced the Government to commit to energy-saving smart meters in every household and forced companies to report their greenhouse gas emissions. In Europe, we secured funding for carbon capture technologies, passed legislation to stop illegal logging and increased building standards to make workplaces more energy efficient. And locally, we are acting every day to cut emissions and improve lives. In Birmingham, homes have been given free wind turbines to generate clean energy. In Camden, north London, every new building has to reuse "grey water". In Eastleigh, Hampshire, the council is on target to be carbon neutral in 2012. And in Richmond, south-west London, every council vehicle runs on recycled cooking oil.

Liberal Democrats are a force for real green change, not just green words. My party has the most detailed and far-reaching climate change policy of any party in Europe. We're the first party anywhere to agree that policies should follow the science, not the politics, and to commit to putting scientists in charge of determining what level of carbon emissions are allowed.

Just imagine what we could achieve in the next Parliament, with your help. We will fight to make Britain carbon neutral by 2050, a plan the Green Alliance described as "the leadership we would expect from the Liberal Democrats". The policies for which we will fight are clear: 100 per cent carbon-free, non-nuclear electricity by 2050, a new high-speed rail network to get people out of their cars and aeroplanes and green loans to help to fund insulation and energy efficiency in every home over the next 10 years. Effective green taxes that make polluters pay for the damage they cause, and protection for the natural environment, too. All of this would make the difference, make Britain a world leader in the fight against climate change and help us to secure the global deals that are needed. We will fight for these policies with all our might and if – with your help – our voice is strong enough, we will succeed.

Many people vote for the Green Party for good reasons. But time is running out, and a vote for a party that probably won't win a single MP is a wasted vote. The best bet for all environmentalists is to unite under the banner of the only green party that's actually got power in Parliament. With your support, the Liberal Democrats will be bigger and stronger than ever, and we will force through the change you want – the change our planet needs.

The clock is ticking. Climate change is worsening. We have one planet, and no second chances. So let us have one voice, too. Lend your vote to the Liberal Democrats, and stop climate change before it is too late.