The price, insisted the European Commission, is a bargain - only one tenth of the price of doing nothing.

The most ambitious bid yet to tackle global warming involves a massive switch to renewable energy sources, and legally-binding targets to cut greenhouse gas emissions by one fifth by 2020 and to boost energy efficiency by 20% by the same deadline.

The overall EU-wide burden will be shared between the 27 member states - with the UK told it must increase reliance on renewable energy from less than 2% now to 15% of the country's total energy needs by 2020, as well as reducing greenhouse gas emissions by 16% by then.

That means major investments in wind energy and biofuels to meet environmental pledges all EU countries entered into last year.

European Commission President Jose Manuel Barroso said the Commission's proposals - which now face months of negotiations between Euro-MPs and EU governments - were the right response to put those pledges into practice.

He said Brussels was leading the first comprehensive climate change offensive in the world to reduce greenhouse gas output by 20% within a dozen years - and by 30% if other nations are prepared to join in.

Environmental groups said the plans were too little, while industry questioned the feasibility of meeting the goals - and paying for them - on time.

Mr Barroso said what was proposed was realistic and financially manageable - the equivalent of about £110 per person per year until 2020 - or three refills of the average car's fuel tank annually. "A reality check is needed - that is one tenth of the cost of inaction" Mr Barroso told Euro-MPs in Brussels.

Environment Secretary Hilary Benn said that the proposals sent a clear signal to the world that Europe was taking decisive action to fight climate change. "This plan shows exactly what we are aiming for globally - a comprehensive and effective agreement to tackle climate change, with the carbon market at its heart. With a global deal, the EU will up its commitment to cut greenhouse gas emissions to 30% by 2020."