Reporting from Washington and Beijing — China vowed Thursday to steeply reduce the intensity of its greenhouse gas emissions over the next decade, a move that environmentalists and the Obama administration hailed as a major, and perhaps decisive, development toward agreement on a comprehensive climate treaty.
The announcement came a day after President Obama unveiled a provisional target to reduce carbon emissions in the United States, and said he would attend climate negotiations in Copenhagen next month.
The promises by the two largest emitters of the gases that scientists blame for global warming dramatically raised expectations for the Copenhagen summit. Until this week, many climate activists considered the prospects for the Dec. 7-18 conference bleak.
The U.S. and Chinese announcements offer a "very much needed boost going into the final steps before Copenhagen," said Jake Schmidt, international climate policy director for the Natural Resources Defense Council.
The Chinese announcement "is a pretty strong signal that China is ready to move forward aggressively on clean energy and global warming," he added.
China's State Council said that by 2020 the country would reduce its carbon dioxide emissions per unit of gross domestic product by 40% to 45% compared with levels in 2005.
This is "a voluntary action based on our own national conditions" and "is a major contribution to the global effort in tackling climate change," the State Council said.
Although the cuts were welcomed, Greenpeace China said the targets did not go far enough, considering the Asian nation's emissions are expected to continue rising. A pledge in the 45% to 50% range would have been better, it said.
And China's gross domestic product is expected to grow, so its total emissions might not drop.
China's pledge was met enthusiastically by leaders in Europe and at the United Nations, where climate chief Yvo de Boer said the vows of emission reductions by China and the United States could help "unlock" an international treaty to curb climate change.
The White House also praised the move by Beijing.
"We welcome China's intention to cut the growth of their emissions by reducing the carbon intensity of their economy," White House Press Secretary Robert Gibbs said.
"Building on the president's productive talks in Beijing, the United States will continue to engage constructively with China on this and other elements of the negotiations going into Copenhagen."
Jonathan Lash, president of the World Resources Institute, noted that the two countries will need to go further in their pledges to reach the levels of commitment of some other nations.
"But the road to an international agreement is now open more than ever," he said.
Still, there were signs Thursday that negotiators have more work to do before completing even a preliminary climate deal in Copenhagen -- and that some countries, particularly those that scientists call most vulnerable to climate change, were unimpressed with this week's announcements.
A group of small island nations Thursday criticized what it called a "lack of ambition" on the part of the United States and other wealthy nations, saying the world's most developed countries must curb emissions more than they've pledged and offer billions of dollars in financial assistance to the developing world. Those island nations wield considerable power in international climate talks.
"These proposals are missing critical elements," Grenada's foreign affairs minister, Peter David, who chairs the 43-member Alliance of Small Island States, said in a statement. But he later added: "With clear, ambitious commitments and actions from the developed countries, individually and collectively, we know that we can succeed."
Schmidt, of the Natural Resources Defense Council, predicted that the negotiators would eventually rally around the "critical" engagement of the United States and China during the conference in Denmark.
In the meantime, he said, "I'm sure there'll be some grumbling in the first week, first week and a half at Copenhagen."
In making its announcement about emission cuts, the Chinese government also said Premier Wen Jiabao would attend the Copenhagen summit.
"Wen's presence at the meeting fully embodies the Chinese government's great attention to the issue and its political willingness to address the issue with international cooperation," Chinese Foreign Ministry spokesman Qin Gang said at a news conference in Beijing.
Despite Greenpeace China's disappointment that Beijing had not gone farther in its pledge, the group's climate campaign manager said that the recent moves by China and the U.S. show a willingness to lead the globe toward a climate solution.
"They're definitely feeling the heat from Copenhagen," said manager Yang Ailun. "The two big countries are setting up a good foundation. China will have to be more energy efficient, which means more renewable energy. They'll have to tackle their over-dependency on coal."