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European nations on Friday dared the United States, Russia and China to follow their lead on global warming after agreeing on a plan to meet the so-called "20-20-20" targets: reducing greenhouse emissions by 20 percent and ensuring that 20 percent of energy comes from wind, sun and other renewable sources by 2020.

But activists said the plan was fatally weakened by a raft of concessions to eastern Europe and heavy industry at a time of worldwide economic crisis.

Stavros Dimas, the European environment commissioner, said the package put the 27-nation European Union on a path to a low-carbon economy.

"We are the only region in the world that is reducing emissions," Dimas said on the sidelines of a U.N. climate conference in Poznan, Poland, calling the bloc an example that others should follow.

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Environmentalists said the concessions made the plan ineffective.

"The deal is a disaster, it's disgraceful," said Stephen Singer, a climate specialist for WWF International. "If the world follows the example of the EU, it is on a trajectory to disastrous climate change."

The plan increased the amount of emissions Europeans could offset by sponsoring green projects in developing countries. Armed with that opt-out, Singer said Europe's actual emissions reductions would be a mere 4 percent, not the 20 percent the EU claims.

The Brussels summit coincided with the end of a two-week, 190-nation U.N. conference in Poznan that worked on a global climate treaty to be adopted next year in Copenhagen, Denmark. The treaty would replace the expiring Kyoto Protocol, which required the EU and other industrial countries to cut carbon emissions by an average 5 percent by 2012.

The EU leaders held out an inducement to the Poznan negotiators: If a global climate deal can be reached in Copenhagen, the EU will go even further, cutting its greenhouse gases by 30 percent by 2020.

President George W. Bush has refused to accept mandatory restrictions on the U.S. economy intended to cut carbon emissions, both as outlined in the Kyoto accord and those now being considered. While the United States signed the Kyoto agreement, it was never ratified by the Senate and Bush essentially scrapped it. Since 1990 U.S. emissions have increased by 16.7 percent.

Sen. John Kerry, D-Mass., who was at the Poznan conference, said he expects the United States to have a climate policy in place within a year that will allow it to join the worldwide effort to combat global warming.

President-elect Barack Obama has called for Congress to establish greenhouse gas limits that would reduce emissions to their 1990 levels by 2020 and cut them another 80 percent by 2050. He also pledged to invest $15 billion a year to develop clean energy projects that produce fewer greenhouse gases.

Yvo de Boer, the top U.N. climate official, said the EU deal showed that "difficult roadblocks (to a global accord) can be overcome and resolved."

He said the EU deal was a "sign of developed countries' resolve and courage the world has been waiting for in Poznan. It shows the world that ambitious emission reduction goals by 2020 are in line with moving economic recovery in a green direction."

The EU leaders spent two days sorting out differences over sharing the burden of cutting greenhouse emissions by 20 percent and ensuring that 20 percent of energy comes from wind, sun and other renewables by 2020.

When it was over, they claimed global climate change leadership, with French President Nicolas Sarkozy, the summit chairman, declaring, "No other continent has given itself such binding rules as we have just adopted."

However, environmental groups called the EU deal a sellout.

Claude Turmes, a Luxembourg Green Party member of the European Parliament, said EU governments were "using the economic downturn as an excuse to water down climate policies."

The heart of the EU agreement is a system — starting in 2013 — of auctioning industrial emission permits that are now issued free of charge. Major polluters will eventually pay $66.1 billion a year for this permission to pollute. Governments will use that income for clean energy development.

But critics say loopholes allow some industries, especially in Poland, Romania, Bulgaria and the Czech Republic, to get largely off the hook, with no incentive to embrace green technologies.

Turmes called the selling of pollution credits "ethically wrong. It implies a neocolonial approach to climate policy."

Jos Cozijnsen, a carbon-trading expert for the New York-based Environmental Defense Fund, calculated Europe would meet half its 20 percent goal by cutting emissions, and half by buying credits. "That's not bad," he said. "It's expensive to do everything domestically."

Elise Ford of the relief organization Oxfam complained that a proposal requiring some auction revenues to go to poor nations was swept from the table.

The cost of the plan had alarmed eastern European countries at a time of economic slowdown.

Desperate to get a deal, France backed several opt-outs to the strict reductions it wants industries to make. The opt-outs are aimed at heavy industries that might flee abroad to regions with looser environmental rules.

The European Parliament must vote on the climate change package next week. They can expect a pep talk from Sarkozy, who made the climate plan the central goal of his six-month run as EU president. France's tenure ends Dec. 31.

EU officials stressed Europe's pollution reduction targets could breathe new life into the U.N. climate talks. The EU plan also pushes eco-friendly cars, fewer power-draining buildings, greener consumer goods and energy deregulation.

"People will not follow Europe unless we set the example," said European Commission President Jose Manuel Barroso.

EU governments agreed in principle to the emissions cuts last year, but spent months working it out. Friday's resulting plan came after diplomats worked through the night for a final compromise. It is highly detailed, with targets and timetables differing from country to country.

The leaders also agreed on a $258 billion European economic stimulus package to ease the effects of a recession.

In the past decade, the EU has largely stayed on track to meet pollution-cutting targets of the 1997 Kyoto agreement.

In November, the European Environment Agency said the 15 nations that belonged to the EU at the time are on target to cut their greenhouse gas emissions by 8 percent in the 2008-12 period. Twelve nations have already surpassed or are set to meet the targets, while Denmark, Italy and Spain will not.