A senior minister was accused of "grotesque hypocrisy" ahead of a speech outlining the government's plan to tackle climate change.
Energy and Climate Change Secretary Amber Rudd said measures to curb rising temperatures are about ensuring economic security.
She also sought to redress the view that green policies are "left-wing".
But Friends of the Earth have accused the Conservatives of "dismantling" 10 years' worth of low-carbon policies.
Ms Rudd is treading a difficult line - Prime Minister David Cameron has promised to lead the world to a climate change deal at a summit in Paris in November.
But Chancellor George Osborne has announced a slew of policy changes which will increase UK emissions.
In recent weeks he has scrapped subsidies for onshore wind and commercial solar - the two cheapest forms of clean energy.
He has also slashed the energy efficiency budget, ended the tax break for clean cars, abolished rules on zero carbon housing, lowered taxes on polluting firms and introduced a tax on clean energy.
Environmental organisation Friends of the Earth said Mr Cameron was "sticking up two fingers" to nations at the French climate summit.
Ms Rudd has to defend the position of both her bosses - and repel those commentators on the political right who believe climate change is not a problem at all.
"It cannot be left to one part of the political spectrum to dictate the solution - and some of the loudest voices have approached the issue from a left-wing perspective," she said.
"So I can understand the suspicion of those who see climate action as some sort of cover for anti-growth, anti-capitalist, proto-socialism.
"But it was Margaret Thatcher who first put climate change on the international agenda. She (said) 'the danger of global warming is real enough for us to make changes and sacrifices, so that we do not live at the expense of future generations.' I agree."
Ms Rudd insisted that the Conservatives' approach was to devise policies to stimulate low carbon businesses and get them off subsidy as soon as possible to keep bills down.
Industry bodies say the government's recent sudden changes to low-carbon policies have created mass uncertainty for investors.
But Ms Rudd said: "The Conservatives are committed to action on climate change and we are clear that our long-term economic plan goes hand in hand with a long-term plan for climate action.
"Climate action is about security, plain and simple - economic security.
"The economic impact of unchecked climate change would be profound. Lower growth, higher prices, a lower quality of life. It is the ultimate insurance policy."
Craig Bennett, head of Friends of the Earth, told BBC News: "This is grotesque hypocrisy from a government that has spent the past few weeks dismantling an architecture of low-carbon policies carefully put together with cross-party agreement over the course of two parliaments.
"They have swept it all away without signalling their intent in their manifesto. They have no mandate for this - it's David Cameron sticking up two fingers to other nations at the climate conference in Paris. Unbelievable."
John Sauven, head of Greenpeace, agreed.
"We are deeply shocked by the vandalism of the government which appears to be driven totally by ideology.
"Their policies will not lead to the low-carbon society they claim they want… they are destroying the UK renewables industry just at the point where it's almost competitive - it's madness.
"We are moving since the election from the 'greenest government ever' to the greyest government ever."
The CBI recently warned that the government's changes were creating massive uncertainty and risking inwards investment into the UK.
But Ms Rudd insisted: "Governments can set the direction, set the vision, set the ambition. We can create the framework, create the rules, provide the support, predictability and stability needed.
"But that support must help technologies eventually stand on their own two feet, not encourage a permanent reliance on subsidy."
The libertarian climate blogger Andrew Montford applauded the government's policy shifts.
He told BBC News: "The environmental and human cost of futile gestures like windfarms and biofuels could not have stopped soon enough.
"This rare glimpse of energy policy sanity in Westminster should be followed by a long hard look at serious low-carbon solutions like modular nuclear reactors."
The UK's policy changes, though, are being noticed internationally.
Previously the UK Climate Change Act has been regarded as a world-leading climate policy but critics say that accolade is now seriously in doubt.
They ask if a country as rich as the UK finds clean energy unaffordable, what hope is there for most of the rest of the world?
Follow Roger on Twitter @rharrabin