Climate Accord Relies on Environmental Policies Now in Place For all the pronouncements about the United States and China reaching a historic climate pact, the agreement they announced Wednesday does not signal a seismic shift in policies by either nation, experts said. The United States and China should both be able to meet the stated goals by aggressively pursuing policies that are largely in place, these analysts said. For the United States, those include the Obama administration's proposal to reduce greenhouse gas emissions from coal plants, which would go into effect in 2017. Experts said that in practice it should be possible to wring more emissions cuts from that and other climate-related measures without adding to costs. "We think that the tools are there to meet this target," said David Doniger, director of the climate program at the Natural Resources Defense Council. Politics, of course, may get in the way - Republicans in Congress vowed to fight the power plant proposal even before it was introduced in June, and some, including Senator Mitch McConnell of Kentucky, who is set to become the majority leader next year, have already sharply criticized the China pact. Policy analysts said a changing energy mix for China, including a buildup of renewable energy sources and nuclear power, had been in the works for some time. "What China is pledging to do here is not a lot different from what China's policies are on a track to deliver," said David G. Victor, who studies climate policy at the University of California at San Diego. Wang Yi, a professor at the Chinese Academy of Sciences in Beijing, said experts in China had reached a consensus that the 2030 date was achievable for its targets, and that 2025 would be a more ambitious goal. The agreement, announced during President Obama's visit with President Xi Jinping in Beijing, calls for the United States to reduce carbon emissions by 26 percent to 28 percent from 2005 levels by 2025. That represents a significant acceleration in the rate of reduction from the president's earlier pledge to cut emissions 17 percent by 2020. President Obama and President Xi Jinping of China announced a climate change agreement on Wednesday that includes a new goal for U.S. carbon emissions and a commitment by China to curb its emissions and increase the share of its energy consumption that comes from renewable and nuclear sources. Mr. Xi said his country would curtail carbon dioxide emissions so that they would peak "around 2030." Mr. Obama pledged that the United States would cut emissions by at least 26 percent from 2005 levels by 2025 - a goal in line with targets he promised in a 2009 United Nations accord. China and the United States emit more than 40 percent of the world's carbon dioxide. The United States has the highest emissions per capita. Share of world carbon emissions Share of world population China has pledged to increase the share of energy consumed from nonemissions sources like renewables, nuclear energy and hydro-electricity to 20 percent by 2030. The country currently relies heavily on coal, a major source of carbon pollution. Energy consumption by source China's goal for nonemissions sources by 2030: The United States has much higher emissions per capita. China's goal for nonemissions sources by 2030: China's Climate Change Plan Raises QuestionsNOV. News Analysis: Fruitful Visit by Obama Ends With a Lecture From XiNOV. In Climate Deal With China, Obama May Set 2016 ThemeNOV. Washington Memo: Republicans Vow to Fight E.P.A. and Approve Keystone PipelineNOV. In Beijing, Clearer Views Hide Real Life NOV. Counting the Varied Costs of China's Dependence on CoalNOV. Obama to Take Action to Slash Coal PollutionJUNE 1, 2014 China's Plan to Curb Air Pollution Sets Limits on Coal Use and VehiclesSEPT. For its part, China has agreed to pursue policies that will lead the country to its peak in carbon dioxide emissions by 2030, or earlier if possible, and to increase the proportion of renewables in its energy mix to about 20 percent by then. Experts said the emissions reductions in the agreement would not be enough to enable the world to keep global warming below the target of a 2-degree Celsius, or 3.6-degree Fahrenheit, rise in global temperatures that was adopted at a climate meeting in Copenhagen in 2009. Beyond the reductions, they said, the deal is important for what it shows the rest of the world, particularly other large carbon emitters like India and Russia, in advance of a meeting in Paris next year to negotiate a new climate treaty. "It shows that the two big dogs in the room are taking the issue seriously," said Kevin Kennedy of the World Resources Institute, a think tank. It provides a real opportunity for the start of what could become a race to the top. But it remains unclear whether that will happen. In India, the world's third-largest carbon polluter, the government of Prime Minister Narendra Modi has signaled that it will not announce a reduction target for emissions cuts. India has long maintained that it should not be required to commit to such goals. Still, the new agreement has given a fresh jolt of optimism to the Paris negotiations, where the American and Chinese targets are expected to be the focus. Nearly two decades ago, the world's first climate change treaty, the 1997 Kyoto Protocol, failed to stop the rise of carbon emissions in large part because of a standoff between China and the United States. Under the new pact, the United States would roughly double the current rate of emissions reductions from 2020 to 2025, to close to 3 percent per year on average. A White House statement said that target was "grounded in intensive analysis of cost-effective carbon pollution reductions achievable under existing law." The administration was short on specifics, but Mr. Doniger said one reason reductions might accelerate might simply be momentum - measures that are already in place will have more impact over time. The Environmental Protection Agency, for example, has already issued vehicle emissions standards that become tighter through 2025. "The improvement ramps up, and that's already done," Mr. Doniger added. Similarly, he said, measures to curb leaks of methane, a potent greenhouse gas, from oil and gas production, which the Obama administration is considering, should have increasing effect as that industry grows over time. "If you have sensible leakage controls, you get a very big reduction," he said. As for the administration's proposal to reduce power plant emissions, called the Clean Power Plan, Mr. Doniger said, some of the calculations were based on cost estimates that were out of date. With more accurate figures, particularly for the cost of renewable energy and energy efficiency improvements, he said, more emissions reductions will be possible under the plan without raising costs. Mr. Kennedy of the World Resources Institute said the United States's commitment to increasing the rate of emissions reductions was an important part of the agreement. "In some ways, it's not where we end up in 2025," he said, "but whether at that point we are increasing the rate of decline in emissions or flattening out." In China, people involved in the internal debates said the seeds of the announcement on Wednesday could be found in public anger over rising levels of smog. To address the problem, Chinese leaders have turned their attention to cutting the country's reliance on coal, a main pillar of the economy but also a major source of pollution. Jake Schmidt, director of the international program at the Natural Resources Defense Council, said the work to reduce emissions had already begun in China, with coal-consumption peak targets in populous areas, and heavy investment in clean energy technology and deployment. "As China takes the next steps, it's got a solid foundation on which to build," he said. And Mr. Xi will not face the kind of political pushback that Mr. Obama does in the United States. They have their own challenges, but effectively, the minute that President Xi Jinping made the announcement, it became the law of the land. Hal Harvey, who runs a policy research group called Energy Innovation in San Francisco and has spent weeks in China this year working on the emissions problem, said that even though the policies already in place or previously announced would take the countries a long way toward meeting their targets, they nevertheless were significant. "In effect, it ratifies stuff that's underway," he said. But I still think it's important. The Chinese take international announcements very seriously, and this has now set a tone for the entire government of what they're going to do. Correction: November 13, 2014 An earlier version of this article misstated the title of Narendra Modi. He is the prime minister of India, not its president.