Member states on Friday legally bound the EU to use 20 percent renewable energy and cut CO2 emissions by 20 percent by 2020 in the hope the US and China will follow, but nobody knows how Europe will make the new "industrial revolution" into reality or who will pay for it, with years of complex negotiations ahead.

"I'm getting the feeling that not only in the US but in the industrialising countries as well, there's growing sensitivity when it comes to realising the importance of these issues," German chancellor and EU president Angela Merkel said. "The member states have said 'Yes. We want to go down this road.' We are proud to hoist our colours to the mast [on climate change]."

"At the G8 meeting in June we can say to the world 'Europe is taking the lead. You should join us'," European Commission president Jose Manuel Barroso said. "This was in my opinion the most significant summit in which I've participated...it was a great moment," he added, talking about the renewables decision in historical terms of making changes "for generations to come."

The EU agreement comes after the UN in a major report last month crowned a decade of research saying human activity is causing potentially catastrophic changes in world temperatures, with the commission predicting that a 5 degree Celsius rise by 2100 could see 40,000 deaths a year in Europe from floods and hurricanes and severe drought in Mediterranean states. EU haggling went on until the last minute on Friday, with Austria resisting then accepting French proposals that nuclear should be on a political par wind or solar power and should somehow count toward meeting renewables and CO2 goals.

"I insisted on placing renewable energy in a larger framework of low-carbon energy," French president Jacques Chirac said at his last EU summit, adding this category includes "nuclear energy."

The crux of the renewables deal lies in letting each member state make a different contribution to the 20 percent target based on how technologically advanced it is already, with Polish experts for example imagining Poland might throw a 10 percent national target into the pot while Denmark might contribute 30 percent.

Work on national targets will start with a commission proposal for a settlement mechanism in autumn, but Ms Merkel acknowledged the risk each EU state will seek special concessions, such as renewable-advanced or nuclear states saying they can do no more. "Each member state sees itself as a special case, so in a sense everybody's equal," she said.