The three main parties today attacked each other's climate change credentials as they set out their policies to attract the "green" vote.
Energy and Climate Change Secretary Ed Miliband was challenged over Labour's "failure" to deliver on renewable energy, tackle fuel poverty and improve air quality in 13 years in power.
But Mr Miliband attacked the Tories over the number of new candidates who are "sceptical" about global warming and the refusal of Conservative councils to give the go-ahead for onshore wind farms.
And he suggested that plans by the Lib Dems to meet ambitious targets to cut emissions without using nuclear power left a "massive hole" in their climate change strategy.
Mr Miliband was joined by shadow energy and climate change secretary Greg Clark, the Lib Dems' climate spokesman Simon Hughes and Green Party parliamentary candidate Darren Johnson at a hustings attended by environmental groups and aid agencies.
The parties agreed on the ambition and urgency of action on climate change, but clashed on how to achieve them.
Mr Miliband said the electorate should judge Labour on its plans, including a commitment to high-speed rail and a new role for local authorities in delivering energy efficiency, and the party's willingness to take "tough decisions" on renewables, nuclear and clean coal.
But Mr Clark said Labour's record after 13 years in power is "feeble", while Mr Hughes said it is too late for the party to claim it is green.
"Ed talks a good talk, but renewables targets are not met, 5% not 10%, fuel poverty not met, air quality targets not met... the Government hasn't delivered," he said.
Mr Miliband said the UK is a world leader on offshore wind, but accused Conservative local authorities of standing in the way of onshore wind, and questioned the party's commitment to the environment.
Mr Clark said: "We have a climate emergency and we have to act on that."
He detailed Tory plans including a "green deal" for every home to improve energy efficiency and a nationwide rollout of "smart meters" by 2016 - four years earlier than Labour proposals.
He said a Conservative government would include an environmental Bill in the Queen's Speech so legislation to tackle climate change would be brought in straight away.
He claimed the Tories' green policies had become "more specific, more ambitious and more radical" over the years.
But Mr Miliband said the Tories are fielding a number of climate sceptic candidates, and that climate change is at the bottom of a list of priorities for would-be Conservative MPs.
Challenged over the views of Torbay candidate Marcus Wood, who has said he is "sceptical" over man-made global warming, Mr Clark said there are people across the country with different views, adding: "I don't agree with him. I've never heard of him."
He said Mr Miliband's approach of labelling people who oppose wind farms as "anti-social" is counter-productive.
"This kind of lecturing from Westminster and officials in Whitehall doesn't work. We should learn from what has worked elsewhere."
He said the Conservatives would follow the lead of Denmark, where many onshore wind farms are community-owned, and would allow local communities to keep the business rates from wind farms for six years, to encourage people to see the opportunities of renewables.
Liberal Democrat energy and climate change spokesman Simon Hughes said there should be a duty on local authorities to play their part in meeting renewables targets and helping cut emissions.
Mr Hughes said his party has a clear commitment to a zero-carbon Britain and would create a green economy with 100,000 jobs, and GBP10,000 for each household to cut emissions.
"This is a fantastic opportunity, and this is the reality of this election, that for the first time in my lifetime there could be in government a party which has a commitment at every level to the green agenda," he said.
He said the party plans, if it is involved in government, to combine the Department for Environment, Food and Rural Affairs (Defra), the Department of Energy and Climate Change (Decc) and the Department for Transport (DfT) to tackle climate change more effectively.
The Lib Dems came under fire from Mr Miliband for ruling out the use of nuclear power, but Mr Hughes said it is expensive, would take too long to come on-stream, the waste couldn't be dealt with safely and it would undermine investment in renewables.
"It's a completely foolish delusion. We don't need it and we shouldn't have it."
But Mr Miliband said: "The scale of climate change is sufficiently great it would be wrong to reject any low carbon tool we have."
Mr Johnson, who is standing in the Lewisham Deptford constituency, warned a "massive transformation" of the economy is needed, and said the scale of the challenge is huge because of decades of "dithering and inaction".
The Green Party is hoping to make its first breakthrough at Westminster, targeting three seats in particular which it believes would give it an influence on the green agenda.
Mr Johnson said his party backs a national rollout of free insulation for homes, a switch of the GBP30 billion earmarked for road building to public transport and a massive investment programme in renewables.
The Independent has been given exclusive rights to broadcast the video footage of the party leaders’ eco-manifestos, below: