Reflecting the urgency and scale scientists have called for to cope with climate change, the U.S. and Chinese presidents laid out ambitious new targets Wednesday to cut pollution in a deal that negotiators hope will inspire similarly dramatic commitments from other countries.

At a news conference in the Chinese capital, President Obama announced that he had agreed the U.S. will cut net greenhouse gas emissions at least 26% by 2025, doubling its current pace of carbon reduction. Chinese President Xi Jinping announced a stepped-up time frame for carbon reduction and for increasing China’s use of nuclear, wind and solar energy.

“This is a major milestone in the U.S.-China relationship and it shows what’s possible when we work together on an urgent challenge,” Obama said, calling it an ambitious but achievable goal.

The deal portends significant change for the climate, observers said, as it sets a bolder timeline for two countries that, together, account for more than a third of global greenhouse gas emissions.


“History may look back and say this was the turning point on climate,” said U.S. Rep. Henry A. Waxman (D-Beverly Hills), ranking member of the House Energy Committee.

The deal was immediately challenged by Obama’s Republican critics on Capitol Hill, who have pledged to make it a priority to roll back the president’s measures on the environment when they assume the majority in Congress next year. The White House did not immediately say whether Obama will propose legislation or use his executive powers to enact changes without lawmakers, though his environmental team expects a fight on the kinds of regulations necessary to carry out his newly set goals.

“This unrealistic plan, that the president would dump on his successor, would ensure higher utility rates and far fewer jobs,” Senate Republican leader Mitch McConnell of Kentucky said in a statement.

The agreement, if it is adhered to and if it prompts similarly far-reaching cuts from other countries, would help put the world on “a straight path to 80% reductions in emissions over 2005 levels by 2050,” said Ken Lieberthal, a senior fellow at the Brookings Institution. Those are the kinds of reductions scientists have recommended to avert the greatest temperature rises associated with climate change.


Obama administration officials also think the agreement could have an exponential effect if it spurs other world leaders to follow suit during global climate negotiations to take place before a summit in Paris next year.

The agreement between “two warring camps” is a sign that the larger international climate talks have “real legs,” as one senior Obama advisor put it.

The deal arrives days after dozens of scientists, backed by the United Nations, issued a sweeping review of the latest research that says climate change is already affecting life on every continent and in the oceans, and the window is closing rapidly for governments to avert the worst damage expected to occur this century.

Analysts say circumstances have changed that make it easier for the two countries to seriously consider emissions reductions, after a major U.N. climate meeting in Copenhagen five years ago ended without significant cuts to greenhouse gases.


But striking the agreement with China was more than most negotiators thought possible until early this year. In a meeting with Chinese counterparts in February, Secretary of State John F. Kerry detected a new receptiveness to the idea, according to a senior administration official who requested anonymity in discussing the months of behind-the-scenes talks.

Obama followed up with a letter to Xi suggesting more ambitious talks, and negotiators have been working on it in the months since.

At a U.N. summit in September to kick off the drafting of an international climate change accord, Obama spoke bluntly of American responsibility for global warming and pledged to unveil ambitious steps over the next year to cut greenhouse gas emissions. Following him at the summit was Chinese Vice Premier Zhang Gaoli, who said China would put forth a plan in early 2015 to put a cap on its greenhouse gases “as soon as possible” and scale back emissions thereafter.

Climate negotiators Todd Stern of the State Department and John Podesta, a senior advisor to Obama, firmed up targets in meetings with the Chinese last week. The deal was finalized late Tuesday night as Obama and Xi huddled at Xi’s residence in a late-night session that went two hours longer than scheduled.


Under the deal, Xi announced targets for capping his country’s carbon emissions around 2030 — earlier than currently planned — and plans to increase the use of alternative energy to account for 20% of the country’s total by 2030. That level of alternative energy would exceed that provided by all of China’s coal-fired power plants right now and be the equivalent of the United States’ total electricity generation.

China will “have to up their game by quite a bit to meet their target” for that kind of alternative power generation, Lieberthal said.

China is now by far the world’s largest emitter of greenhouse gases, and carbon emissions per capita have reached the level of the European Union. Its severe air pollution has become a source of domestic discontent and international embarrassment that Chinese leaders can no longer ignore, said Wang Yiwei, director of the Institute of International Affairs at People’s University in Beijing.

“Climate change is now Chinese business. It’s not just someone from the outside pressing” us, he said.


China is investing heavily in renewable and nuclear energy, and the economy is slowing. By some estimates, China’s coal consumption this year might actually drop 1% to 2%, for the first time in decades. Beijing wants to shift its economic model toward one of less rapid, more “sustainable” growth and more sophisticated, less-polluting industries.

The joint announcement immediately received extensive coverage in the foreign media, but China’s state-run press was slow to publish reports about the climate change agreement. Hours after Xi and Obama spoke, only brief articles were available from the official New China News Agency.

It wasn’t clear why this was the case but it didn’t necessarily indicate a lack of commitment by Chinese authorities, said Ma Jun of the Institute of Public and Environmental Affairs.

“The focus in China is a little different than in the West because China is facing multiple environmental challenges – air pollution, water pollution, soil contamination -- whereas in Western countries, those problems have largely been controlled and climate change is instead highlighted,” he said.


The announcement also helps set the tone for a meeting in Lima, Peru, in December where the parameters of the final United Nations accord will be established. That agreement is due to be signed in Paris in December 2015.

The accord is meant to create a system to verify the cuts that countries pledge, and how transparent such a system will be remains unknown. Lieberthal also cited Russia, Saudi Arabia and India — a nation he called a “huge unknown” — as needing to commit to cuts for progress to be made.

And Obama’s ambition to create a legacy of fighting climate change faces obstacles other than Congress. The administration’s power plant rules could be weakened or nullified if courts decide against them in a welter of lawsuits filed against the Environmental Protection Agency. A new president in 2016 could also reverse the rules, Lieberthal pointed out.

In China, authorities were forced to take extraordinary measures before the economic summit to clear the often-smoggy skies around Beijing. Hundreds of factories were shut, people were allowed to drive their cars only every other day, and even cremations were curtailed. But all the fuss over clearing the skies for foreign visitors has irritated the Chinese public, who must breathe polluted air year-round.


At a welcome banquet Monday night, Xi told foreign dignitaries that the first thing he was doing each morning was checking the air quality in Beijing and “hoping that the smog won’t be too bad so that our distinguished guests will be more comfortable.”

But perhaps foreshadowing the agreement announced Wednesday and addressing his domestic audience, Xi added: “My hope is that every day we will see a blue sky, green mountains and clear rivers, not just in Beijing, but all across China so that our children will live in an enjoyable environment.”

Parsons and Makinen reported from Beijing and Banerjee from Washington. Times staff writer Kathleen Hennessey in Washington contributed to this report.