COPENHAGEN, Denmark — The United States and China exchanged barbs Wednesday at the climate talks, underscoring the abiding suspicion between the world's two largest carbon polluters about the sincerity of their pledges to control emissions.
U.S. chief negotiator Todd Stern urged China to "stand behind" its promise to slow the growth of the country's carbon output and make the declaration part of an international climate change agreement.
China rejected that demand and renewed its criticism of the United States for failing to meet its 17-year-old commitment to provide financial aid to developing countries and to reduce emissions of carbon dioxide and other gases warming the Earth.
"What they should do is some deep soul-searching," said Yu Qingtai, China's chief negotiator.
The remarks showed the hard work that remains in the 10 days before 110 heads of state and government end the summit, which aims to create a political framework for a treaty next year to succeed the 1997 Kyoto Protocol.
President Barack Obama helped break the ice last month, saying he would pledge at Copenhagen to reduce U.S. greenhouse gas emissions by around 17 percent from 2005 levels by 2020. It will be the first time the U.S. has committed to a reduction target.
China responded a day later, announcing it would voluntarily reduce the carbon intensity of its industry by up to 45 percent, meaning its emissions would continue to grow but at a rate lower than the economy.
Stern said China's announcement boosted optimism but didn't go far enough: "What's important is not just that they announce them domestically but they put them as part of an international agreement."
Whatever actions the Chinese take to slow emissions growth should be transparent, he said. "It's not just a matter of trust."
The Chinese delegate accused the Americans and other wealthy countries of insincerity when they signed the 1992 climate convention promising voluntary carbon reductions. The convention was amended five years later in Kyoto, making reductions mandatory for most industrial countries. The United States rejected the protocol because it did not include China or India.
During the talks Wednesday, the tiny Pacific island of Tuvalu seized the initiative with a demand that the conference go beyond a political deal and negotiate a new protocol with the same legal standing as Kyoto.
Tuvalu and other island nations are threatened by rising sea levels that scientists say will engulf low-lying areas as Arctic ice sheets and mountain glaciers melt.
"Our future rests on the outcome of this meeting," said Tuvalu delegate Ian Fry.
But in an unusually open split among the developing countries, China refused to support Tuvalu's motion for an open debate on its draft protocol. The rebuff doomed the island state's initiative.