(AP) -- U.S. Secretary of State Hillary Rodham Clinton sought to put new life into flagging U.N. climate talks Thursday by announcing the U.S. would join others in raising $100 billion a year by 2020 to help poorer nations cope with global warming.
The $100 billion figure, the first offered by Washington in discussions here over long-term financing, falls short of what some experts suggest will be needed. Yvo de Boer, U.N. climate chief, said talks would focus on the "adequacy" of that target.
Clinton made the offer contingent on the 193-nation conference reaching a broader agreement, including on the issue of "transparency" - demanding a Chinese commitment to allow some kind of oversight to verify its actions to control emissions of carbon dioxide and other greenhouse gases.
The Chinese thus far have resisted what they see as a potential intrusion on their sovereignty. But without that, Clinton told reporters, "there will not be the kind of concerted global action that we so desperately need."
Clinton's arrival and announcement in snowy Copenhagen ratcheted up the U.S.-Chinese diplomatic dueling that has marked the two weeks of talks. The negotiations end Friday with a summit gathering of President Barack Obama, Chinese Premier Wen Jiabao and more than 110 other national leaders.
For China's part, a Foreign Ministry spokeswoman in Beijing told reporters that developed countries should show "more sincerity" in the talks in Copenhagen.
Environment ministers, having taken over from lower-level negotiators, were getting down to final hours of talks in hopes of producing partial agreements to put before Obama, Wen and the other leaders.
Such accords might include long-term goals for financing climate aid, raised by Clinton, and monitoring of emissions controls.
But organizers of the U.N. conference probably will not get the climate deal they had hoped for, one Danish official said Thursday. The official was not authorized to talk publicly about the talks and spoke on condition of anonymity.
British Prime Minister Gordon Brown was among those stressing the time left, not the time lost.
"We can, by working together over the next 48 hours, reach agreement that will help the planet move forward for generations to come," he told reporters.
The European Union issued a statement expressing concern over "the lack of progress in the negotiations."
The detailed talks on a range of issues - from emissions commitments, to preventing deforestation, to transferring clean-energy technology - reached an impasse Wednesday when developing nations objected to the process that produced a core draft document.
In a reprise of a perennial complaint at the annual conferences, the poorer nations complained they were being excluded from the drafting of the text, that the views of wealthy countries were being imposed on the developing ones.
The Clinton offer on long-term climate financing for developing countries reflected an amount - $100 billion - that Britain's Brown has previously suggested, to help poorer countries build sea walls against rising oceans, cope with unusual drought and deal with other impacts of climate change, while also financing renewable-energy and similar projects.
"It's good there's now been a statement of support for a clear number on long-term finance," de Boer said of the U.S. offer. "This discussion will have to take place with other parties, whether they feel that sum is adequate."
Expert studies, by the World Bank and others, have estimated the long-term climate costs for poorer nations, from 2020 or so, would likely total hundreds of billions of dollars a year. China and other developing countries say the target should be in the range of $350 billion.
In addition, the developing nations want long-term financial support based on stable revenue sources, such as an aviation tax that might be the goal of future international climate talks.
More immediately, the conference has been discussing a short-term climate fund to help developing countries - a $10 billion-a-year, three-year program. EU leaders last week committed to supplying $3.6 billion a year through 2012. On Wednesday, Japan, seeking to "contribute to the success" of Copenhagen, announced it would kick in $5 billion a year for three years.
U.S. funding is hovering at only around $1 billion this year, and Clinton, when asked, did not specify how much Washington would contribute to the "fast start" package.
"We'll do our proportion of `fast start'," the secretary of state said.
De Boer commented afterward: "I'm keenly looking forward to hearing what the U.S. contribution to that fund will be."
The "transparency" issue relates to recent pledges by such major developing countries as China, India and Brazil to rein in the growth of their emissions by specific amounts - on a voluntary basis.
Under the 1997 Kyoto Protocol, 37 industrialized nations that must cut their emissions - excluding the U.S., which rejects Kyoto - are required to file detailed reports to the U.N., where they are subject to review.
China and other developing nations were not required to reduce emissions under Kyoto or file regular greenhouse-gas "inventories." Now that they have pledged voluntary controls, the United States wants their emissions actions to be "measurable, reportable and verifiable," in U.N. terminology.
The issue is particularly sensitive in the U.S. Congress, where members want to ensure China is living up to its own internal commitments. "It's essential for the global effort, but their internal efforts as well," House Speaker Nancy Pelosi told reporters in Copenhagen.
U.S. Sen. John Kerry, D-Mass., said he had discussed the issue with Chinese officials Wednesday and progress was being made. Conference observer Jake Schmidt, of the New York-based Natural Resources Defense Council, suggested the Chinese might satisfy their critics by submitting yearly reports, with more detail.
Meantime, the U.S. came under renewed pressure to improve its pledge of greenhouse-gas emission cutbacks - by about 17 percent by 2020, compared with 2005 figures. That's only a 3 percent to 4 percent reduction from 1990, the benchmark year for the Kyoto countries and the basis for the EU's pledge to cut emissions by at least 20 percent by 2020.
"I have to be honest, an offer by the United States to cut only 4 percent from 1990 levels is not ambitious enough," German Chancellor Angela Merkel told lawmakers in Berlin before arriving in Copenhagen.
One expert analysis of industrialized countries' current pledges on emissions in 2020 find that in aggregate they amount to 8 percent to 12 percent below 1990 levels, far below the 25 percent to 40 percent recommended by the Intergovernmental Panel on Climate Change, the U.N. scientific network.
Climate Action Network International, the coalition of environmental groups at the conference, estimate that emissions path would raise global temperatures about 4 degrees Celsius (7 degrees Fahrenheit) by mid-century, well beyond what scientists say is a 2-degree C (3.6-degree F) threshold for seriously damaging climate change.
Explore further: FACT CHECK: Both sides in Keystone XL debate bend facts