An over-reliance on gas-fired power stations risks making it impossible for Britain to meet targets on cutting carbon emissions, the new head of the independent climate change watchdog has warned.
The intervention by Lord Deben, who as John Gummer was a secretary of state for the environment in the Major government in the 1990s, comes as the coalition's green credentials are again thrown into doubt by claims that climate sceptics were promoted in the reshuffle and steps towards major expansion in airport capacity are being taken.
Lord Deben, chosen by David Cameron to head the independent Committee on Climate Change, told The Independent on Sunday that politicians risk delaying difficult decisions over the environment and that a reliance on gas in the short term will mean gas-fired powered stations approved over the next few years will dictate future policy.
"It would be perfectly possible to miss the [carbon emissions] target if we make the wrong decision about the precise amount on which we depend on gas," he said.
The coalition has faced accusations of a "dash for gas" since announcing in March new rules that would block any more coal-fired power stations, but allow gas power until 2045. Some senior Tories, including George Osborne, have been reluctant to sign up to restrictions on gas, believing a breakthrough in carbon capture and storage could be imminent, while shale gas supplies could cause prices to fall. The Climate Change Act commits Britain to reducing carbon emissions by 80 per cent of 1990 levels by 2050.
Lord Deben, who is due to have his appointment as chairman of the climate change watchdog confirmed within weeks, said: "There is a problem with it, which is that you cannot say 'It will be alright for a bit'. The real difficulty is you end up with a whole infrastructure that you use for gas, and then infrastructure drives policy.
"If you're not careful, what happens is each generation of politicians pushes the difficult decisions back. So you suddenly find yourself in 2035 with 15 years to go [until the 2050 target] and you have not done the hard things. By 2035 even the least willing to understand [climate change] will see what is happening … but it will be too late to do it in an orderly, cost-effective way."
Some senior Tories believe a breakthrough in shale gas – released by blasting water and chemicals at pressure into rock in a process known as "fracking" – could create a major new energy supply and bring down costs. However, in May, this newspaper revealed companies, including Shell, Centrica and Schlumberger, had warned Mr Cameron at a Downing Street summit that Britain's shale gas reserves were "not a game-changing amount". Last week, Mr Osborne announced a new £160m tax break for older oil and gas fields in the North Sea.
Ed Davey, the Secretary of State for Energy, insisted there was a place for gas, but it would be balanced with renewables. He said: "A fifth of our power stations are closing over the next decade, and we need to build a diverse mix of all the technologies to keep the lights on and emissions down. Our gas strategy is about ensuring sufficient investment comes forward, while also living within our legally binding carbon budgets."
Last week's government reshuffle has also reopened doubts about the Conservatives' commitment to the green agenda: Owen Paterson, the new Environment Secretary, has been described as a climate sceptic and a supporter of shale gas. A fresh move to loosen planning restrictions and a review of airport capacity which could pave the way for a third runway at Heathrow have also dismayed environmentalists.
Joss Garman, senior campaigner at Greenpeace, said: "Last week's reshuffle looks like a headlong rush towards the sort of toxic, nasty party politics that David Cameron said was history when he told voters to go green, vote blue. With the Chancellor pursuing a new dash for gas burning, roads and runways, and a new Environment Secretary who refuses to deny reports that he won't accept the science of climate change, it's more important than ever that Nick Clegg stands up for the millions of people who want to protect our environment."
An ally of Mr Paterson insisted he was not a climate denier, but he wants more evidence. The friend added: "He has not bought into the deification of man-made global warming. He is a sceptic." In 2007, Mr Paterson described wind farms as ridiculous, claiming they "demand vast amounts of public subsidy and do not work".
While responsibility for tackling global warming lies with Mr Davey, a Liberal Democrat, there are growing tensions in the coalition about environmental policy. "Owen Paterson is just so far away from our politics," said a senior Lib Dem. "There is going to be a battle over green policy which is going to last for the rest of this Government."
Another major battle looms on the Government's aviation policy. Last week, Mr Cameron appointed Howard Davies to lead an independent commission into increasing airport capacity, after shifting Justine Greening, who opposes a third runway at Heathrow, from Transport to International Development. However, Mr Davies was once a special adviser to former chancellor Nigel Lawson, one of the most outspoken climate sceptics in Britain.
Emissions targets allow for an increase from aviation, but Lord Deben warned that those arguing for a major expansion in aviation to boost the economy, and a subsequent further rise in emissions, ignore the targets which mean that "if you move the amount of emissions that you accord to aviation up, you have to reduce emissions that other parts of industry can give out".
While still an MP, he described Heathrow expansion as "utterly unnecessary and unacceptable". Now he says only: "I have my views and those are in the record."
The appointment of climate sceptic Owen Paterson as Environment Secretary dismayed green groups, even though climate change policy lies elsewhere in Energy. And green Tory modernisers, including Greg Clark, Nick Boles and Dan Poulter, were promoted. Even so, the Lib Dems warn of a green battle until 2015
The biggest chink in the government's green armour. Any expansion in airport capacity will be opposed by environmentalists. David Cameron promised "No ifs, no buts, no third runway" at Heathrow. Now a U-turn is taxiing into view, that would bury the slogan "Vote blue, go green".
Despite high-profile cock-ups (cutting subsidies for solar panels) and controversies (Tory MPs demanding an end to onshore wind farms), the coalition's record on renewables is surprisingly good. In the first three months of this year, they accounted for 11 per cent of the UK's electricity, up from 7.7 per cent in 2011.
Oil and gas
In March, George Osborne announced a £3bn tax break for oil firms to drill new wells off the north of Scotland. Last week, he revealed a £160m tax break for older oil and gas fields. The Chancellor has fought for gas to play a larger part in the energy mix as "the largest single source of our electricity in the coming years".
In the desperate hunt for economic growth, planning rules are to be relaxed. Councils will be told they can tinker with green belt rules, while homeowners will be able to build larger extensions without permission. The Royal Horticultural Society warns of a greater flooding risk.