By Roger Harrabin
Environment analyst, BBC News
EU leaders will discuss everything from climate change to relations with Russia
Green groups are fearful that a summit opening in Brussels will see attempts to dilute the EU's climate and energy package because of the economic crisis.
Multi-billion-euro bank rescue schemes are due to dominate the two-day meeting of EU leaders but they will also discuss the climate change package.
The EU's environment commissioner has told the BBC that the target of a 20% cut in emissions by 2020 still stands.
But states may be able to trade away part of their emission cut obligations.
Stavros Dimas has said that governments should be able to achieve more than half of their target carbon cuts by paying developing countries to invest in clean energy projects on their behalf.
The commission originally said that not more than a third of Europe's emissions targets should be traded away in this fashion.
But in an interview with BBC News Mr Dimas said: "If we put together the sectors covered by the emissions trading system and those sectors like transport, agriculture, waste, households, we have 50% - perhaps a bit more than 50% - of the effort that could be done abroad."
A British government source reacted angrily to the suggestion, saying that it would undermine Europe's credibility on climate change.
Mr Dimas's proposal will also be resisted by the European Parliament.
They will point to a Commission declaration in January that said: "The (35% trading) limits are in place to ensure that the package triggers investment in cleaner technologies and renewables.
"Higher limits might mean that targets could be missed, with Europe straying from the path towards a low-carbon economy. They should also ensure that Europe has greater leverage in international negotiations."
Mr Dimas's proposed change is a sign that the EU climate and energy package is facing severe challenges because of the current financial crisis.
Germany, for instance, is insisting that its exporting industries, such as cars, should be shielded from international competition.
Mr Dimas says he is considering plans to delay the imposition of carbon permits on some energy-intensive sectors, or to give free allowances to car firms.
He says there is no point forcing jobs to migrate to countries where carbon regimes are more lax.
Environmentalists agree in principle, but fear the result will be an erosion of Europe's climate ambitions.
"The world desperately needs leadership from the EU, in order to ensure that a strong global deal to combat climate change is brokered in Copenhagen next year," said Kirsty Clough, WWF-UK's climate change policy officer.
"We cannot avoid our responsibility for delivering emission reductions at home, nor can we allow the EU to backtrack on the European Parliament's recent call for half of the revenues from auctioning pollution permits to be given to developing countries.
"By trying to shirk our responsibility to tackle climate change at home, these proposals demonstrate how dangerously close we are to becoming 'offset Europe'."
The Polish government has been threatening a revolt over the EU's scheme to force power firms to buy pollution permits at auction.
Poland fears this will increase energy prices and increase its dependency on Russian gas.
On Tuesday, Polish Environment Minister Maciej Nowicki said his country wanted changes in the climate package because of the cost.
"Poland does not fear reducing emissions by 20% by 2020 but the way of achieving this is at present is not acceptable [to us]," he told reporters.
A very senior member of the Commission told BBC News six months ago he wanted nation states to use all the proceeds from auctioning - tens of billions of euros a year - to create the transition to a low-carbon economy in Europe.
But this proposal was resisted by member states and Mr Dimas's current message to the Polish government is much more seductive: you can keep all the proceeds from carbon auctioning for government revenue and use it for whatever you want.
He said the Commission would still like to see at least 20% of the funds earmarked for green causes but pointed out: "It's not mandatory so there remains some room for the member states not to use the funds for what we would consider to be good causes like promoting carbon capture and sources or energy efficiency or renewable energy."