President Obama is expected to announce on Monday an Environmental Protection Agency regulation to cut carbon pollution from the nation’s fleet of 600 coal-fired power plants, in a speech that government analysts in Beijing, Brussels and beyond will scrutinize to determine how serious the president is about fighting global warming.
The regulation will be Mr. Obama’s most forceful effort to reverse 20 years of relative inaction on climate change by the United States, which has stood as the greatest obstacle to international efforts to slow the rise of heat-trapping gases from burning coal and oil that scientists say cause warming.
The president had tried, without success, to move a climate change bill through Congress in his first term, and such legislation would now stand no chance of getting past the resistance of Republican lawmakers who question the science of climate change. So Mr. Obama is taking a controversial step: He is using his executive authority under the 1970 Clean Air Act to issue an E.P.A. regulation taking aim at coal-fired power plants, the nation’s largest source of carbon pollution.
“I am closely watching this. This standard is the real test of how serious the Obama climate action plan really is,” said Qi Ye, director of the Climate Policy Center at Tsinghua University in China. The university is one of about half a dozen institutions that the Chinese government has tasked with immediately analyzing the new rule, according to Chinese experts.
China and the United States, the world’s two largest economies and greenhouse gas polluters, are locked in a stalemate over global warming. While today China pollutes more than the United States, Chinese officials insist that, as a developing economy, China should not be forced to take carbon-cutting actions. China has demanded that the United States, as the world’s historically largest polluter, go first. Chinese policy experts say that Mr. Obama’s regulation could end that standoff.
“If the standard is really stringent, that will make a difference in the domestic debate in China,” Mr. Qi said.
Mr. Qi said that while he did not expect the Chinese government to publicly comment on the E.P.A. rule, a strong regulation — like one that led to a 20 percent cut in coal plant pollution — could stimulate policy changes. “It will have an impact,” he said.
The E.P.A. rule comes at a crucial moment in the fraught international effort to slow global warming. In March, the American Association for the Advancement of Science, the world’s largest general scientific society, released a report warning that human-caused climate change is leading to food and water shortages, extreme heat waves and droughts, rising sea levels, and stronger storms.
But scientists have also warned that collective action, with carbon cuts by all the major economies, is essential to achieve the drastic reduction in carbon pollution necessary to stave off the most destructive impacts of global warming.
This December, leaders from many nations will gather in Lima, Peru, at a United Nations summit meeting aimed at drafting a treaty, to be signed in 2015, that would legally bind the world’s major economies to cut their carbon pollution.
The goal is to avoid the debacle of the 1997 Kyoto Protocol, the world’s first attempt to forge a climate change treaty, which was effectively rendered null when the United States Senate refused to ratify it.
But as Mr. Obama moves ahead using his existing authority under the Clean Air Act, governments around the world have taken notice — and tried to learn everything they can about the law.
“We’re very excited to see the new rule on existing power plants. We see this as absolutely the backbone of U.S. climate strategy,” said Günter Hörmandinger, environmental counselor to the European Union delegation in Washington. The European Union, which enacted a carbon-cutting policy after the Kyoto Protocol, has been among the critics of the United States’ climate change policy.
“Once it’s out, I will be rushing to understand it and report back to Brussels,” said Mr. Hörmandinger, an Austrian who has spent the past four years studying the Clean Air Act.
Within the United States, opponents of the climate change rule, chiefly the nation’s coal industry, are preparing to fight with lawsuits, and global analysts are assessing whether the rule will stand up to those attacks.
“I think it can be done legally, going back to the Supreme Court decision that led to E.P.A.’s authority to regulate carbon emissions,” said Mario Molina, a climate policy adviser to President Enrique Peña Nieto of Mexico.
Mexico, which enacted an ambitious climate change law in 2012, has urged other Latin American nations to pass similar legislation.
Many governments are also mindful of the opposition to climate change science in the United States Congress.
Peru’s environment minister, Manuel Pulgar-Vidal, paid attention when Senator Marco Rubio, a Florida Republican who is viewed as a potential presidential candidate in 2016, questioned the science of climate change this month on ABC News’s “This Week.”
“Senator Rubio shows us that there are still people who are skeptical of the science, even though we are already suffering the consequences of climate change,” Mr. Pulgar-Vidal said. “The government faces resistant actors, skepticism from political leaders — it’s the same in the international arena.”
Perhaps no governments are anticipating the rule with more urgency than those in the small island nations that could be threatened if sea levels rise. A series of scientific reports have concluded that as the planet warms, melting polar ice will drive up sea levels two to four feet by the end of the century, threatening the very existence of some of those islands.
“The path we’re on right now is that our country will disappear,” said Ronald Jean Jumeau, the United Nations ambassador from the island nation of Seychelles, and a spokesman for the Alliance of Small Island States. “This will slow things down and give us more time to adapt and restructure our economies. Taking action now gives us more breathing room.”
Also paying close attention will be Saudi Arabia, which has sought to block global action on climate change. Economies that are deeply dependent on producing fossil fuels fear that lowering the global demand for oil and gas presents a grave economic threat.
“Everyone knows that the U.S. is key to achieve any solution to the climate change crisis,” wrote Wael Hmaidan, director of a Lebanon-based advocacy group, Climate Action Network. “Many OPEC countries, who do not want to see the world wean itself from fossil fuels, realize this.”
One world capital that will not be paying much attention is Moscow. President Vladimir V. Putin of Russia is an open skeptic of climate science, and Russia, as one of the world’s largest producers of oil and gas, has generally been dismissive of efforts to forge a climate change treaty.
“Climate change is snubbed in Russia,” said Vladimir Milov, a former Russian deputy minister of energy and president of the Institute of Energy Policy, a Moscow think tank. “It is a very climate-change-skeptical society.”