The UK must increase by sevenfold the proportion of its energy coming from renewables to meet European commission targets on carbon emissions outlined in Brussels today.
The commission confirmed the goal of cutting 20% from Europe's carbon emissions by 2020 compared with 1990 levels, and generating one-fifth of the EU's power from renewable sources by that time.
As its contribution, Britain must get 15% of its energy for heat, electricity and transport from renewables such as wind, wave, tidal, solar and biomass.
Only 2% of the UK's energy is renewable - the lowest percentage of any major European country.
Britain must cut greenhouse gas emissions by 16%, and get 10% of road transport fuel from biofuels, subject to them being produced in a sustainable way.
The business secretary, John Hutton, said the government was already doing a major review of its climate change strategy and was committed to meeting its EU targets.
But he said the final figure committed by Britain would be set in negotiations between ministers based on today's commission proposals.
"Whatever the final outcome, the UK is already exploring a vast expansion of wind energy offshore, and tidal power on the Severn, and we are already thoroughly reviewing our strategy to drive progress further," he said.
The commission president, Jose Manuel Barroso, urged European governments to play their full part in achieving what he called the world's most comprehensive deal on climate change.
He said they would increase energy security as well as addressing climate change, while creating thousands of new businesses and millions of jobs.
He told MEPs that the EU was determined to lead the way in facing up to the most important challenge of the 21st century. The EU was ready to increase its CO2 reduction target to 30% as soon as the rest of the world made significant commitments, he said.
The targets, which must be endorsed by MEPs and member governments and would come into force in 2009, are different for the 27 members states according to their circumstances.
There are measures to support the development of carbon capture and storage (CCS) technology, an overhaul of the carbon trading scheme, and sustainability criteria for biofuels.
Green groups said the commission had not gone far enough. The director of Friends of the Earth UK, Tony Juniper, called the plan a "disgrace".
"Europe wants to be a world leader in tackling global warming, but its carbon-reduction target is far weaker than the one agreed at last month's UN climate summit in Bali," he said. "Scientists warn that a cut of at least 30% is required to prevent a climatic catastrophe. The EU must take urgent action. The solutions already exist, what we lack is political ambition and courage.
"Although the UK has one of the biggest renewable energy potentials in the EU, we lag behind most of our European neighbours in developing green power. The government must revolutionise its support for renewables."
Greenpeace said a major shift in government priorities was needed to meet the targets.
"Britain is set to embark on a clean energy revolution, and it's vital that we approach this with a can-do attitude," said the Greenpeace executive director, John Sauven. "Gordon Brown deserves praise for committing to this target, and if his government can deliver it we will have closed the energy gap with clean, reliable technology, created thousands of green-collar jobs and safeguarded our energy supplies – as well as setting an international example on climate change.
"We now need a completely new industrial policy to make this happen, supporting the engineers and business leaders who can make the target a reality. Just as important is a step change in government thinking, where for too long civil servants at the Department for Business, Enterprise and Regulatory Reform have treated the renewables industry with utter contempt."
Stephen Singer, head of the European climate and energy unit of the WWF, said: "The European commission presented a relatively weak proposal and not a single European country supported more ambitious targets ... Overall, it is a very small effort to cope with a threat that might lead to Arctic melting and displacement of millions of people in developing countries because of increased floods."
Green MEP for the south-east, Caroline Lucas, said: "It is a serious source of regret that the EU commission has based its climate package on a mere 20% greenhouse gas reduction by 2020.
"Member states have committed to a 30% greenhouse gas reduction (which is in line with the reduction scientists agree is the minimum necessary) assuming an international agreement is reached. By setting the bar lower from the outset, the EU is negatively prejudging the outcome of international climate negotiations and sending the wrong signal to the rest of world."
The Renewable Energy Association's chief executive, Philip Wolse, said the UK government's response to the proposals "lack sustenance and urgency".
"We have been reviewing this area for years. We should be using biomass for energy, not paper for more reports," he said.
"Ministers admitted in last year's energy white paper that present policies will only deliver a 5% contribution from renewables to the UK's energy by 2020. They signed up to the European 20% target last March – has nothing been done since?"
"The European commission has been gentle giving us a below-average target especially considering we have the best wind, wave and tidal resources in Europe."
Biofuels
The commission has stuck with its target of biofuels for 10% of all road fuel in Europe - and in Britain - by 2020, but introduced sustainability criteria because of fears about the environmental impact of growing fuel crops.
Biofuels used in the EU must be proven to provide a real saving in emissions of at least one-third compared with fossil fuels, and be produced using agricultural best practices. They must not be produced on "land of high biodiversity" or with high carbon stocks.
The transport secretary, Ruth Kelly, said: "The UK has been leading the international drive to make sure the biofuels we use come from sustainable sources and we will be pressing to make sure European biofuels policy also includes strong safeguards to maximise greenhouse gas savings and protect the environment."
But Robert Bailey, Oxfam's international spokesman, said the strategy "failed to protect the land, livelihoods and human rights of vulnerable people, and create a huge threat to sustainable development where there should have been an opportunity".
"It is untenable for the commission to proceed with this legislation in the knowledge that it is unlikely to deliver on its primary policy objective of reducing emissions from transport."
Carbon trading
The proposals include an overhaul of the EU's emissions trading system, with plans to auction emissions permits that were previously handed out for free.
The commission wants to cut the allowances allocated to member states by a fifth by 2020, and favours an EU-wide emissions cap instead of the previous allocations for individual countries.
The scheme allocates a fixed quota of CO2 emissions permits to heavy polluters, but allows companies to trade the credits among themselves.
It proposes to expand the scheme to airlines and industries such as cement, steel and paper.