The divergence of policies and priorities of the world's two largest economies in combating climate change stood in stark contrast on Monday. In Beijing, where improving air quality has become a major policy priority, China's top economic planner unveiled plans for a national carbon market－likely the world's largest－where enterprises can trade their emissions credits. It is another bold step the country is taking to deliver on its Paris Agreement promises.

In contrast, Washington policy observers were quick to point out that the new US National Security Strategy released by the White House on Monday had removed climate change from the list of worldwide threats menacing the United States. It was a significant departure from the Barack Obama administration, which described climate change as an "urgent and growing threat" to US national security.

The initial phase of China's carbon trading program is expected to cover 1,700 power plants, which emit 3.3 billion metric tons of carbon annually, or about one-third of the nation's total emissions, according to the National Development and Reform Commission.

Additional sectors such as cement and aluminum will be phased in over the coming years, the Environmental Defense Fund said in a release on Tuesday.

"The world has never before seen a climate program on this scale," said Fred Krupp, president of the New York-based organization, which provided technical assistance to China's carbon trading pilot programs. "It's important that the world's largest emitter should lead on climate, and that is precisely what China is doing by launching its national emissions trading system."

In its latest Global Energy Outlook released earlier this month, the International Energy Agency predicted China's coal use, which peaked in 2013, is set to decline by almost 15 percent by 2040.

China's policy choices will play a huge role in determining global trends and could spark a faster clean-energy transition, the IEA noted.

In a speech at the landmark 19th National Congress of the Communist Party of China in October, General Secretary Xi Jinping vowed to promote green development and ramp up the campaign to prevent and control air pollution.

The country is also transitioning toward a more services-based economy, which the IEA said "is moving the energy sector in a new direction".

The IEA's outlook says stringent fuel-efficiency measures for cars and trucks, and a push for 1 in 4 cars being electric by 2040, means that China is no longer the main driving force behind global oil use.

It further projected China's carbon emissions to plateau at 9.2 gigatonnes, only slightly above the current level, by 2030, which means it'll meet the promise it made when signing the Paris climate pact in 2015.

It is noticeable that on Monday the IEA published its Coal 2017 report, cautioning that coal use will see a decade-long period of stagnation, with the share of the fossil fuel in the global energy mix forecast to decline to 26 percent in 2022.

Back in Washington, the omission of climate change as a national security threat in President Donald Trump's first National Security Strategy is a logical follow-up to the climate change skeptical administration's effort to roll back the rules and regulations of the Obama administration, which were designed to reduce carbon emissions, including those from coal-fired power plants.

And that is a source for concern, as US Senator Michael F. Bennet, a Democrat from Colorado, pointed out on Twitter: "One topic noticeably missing from #NationalSecurity-Strategy: Climate change. Bipartisan group of lawmakers have acknowledged#climatechange as a national security threat. @POTUS silence is cause for serious concern."

The author is deputy editor-in-chief of China Daily USA. huanxinzhao@chinadailyusa.com