In that announcement, the US has promised to cut net greenhouse gas emissions by 26 to 28 percent below 2005 levels by 2025. Meanwhile, China announced targets to peak CO2 emissions around 2030, with the intention to try to peak early, and to increase the non-fossil fuel share of all energy to around 20 percent by 2030.

Taylor said Obama's State of the Union address in 2014 had only two mentions of China, both emphasizing it as a competitor.

"This year he managed to mention China three times. I would not categorize that as progress," Taylor said.

"China is mentioned negatively twice on trade and positively once on climate change," he said.

"While rarely mentioning China in his address, Obama definitely had China on his mind with issues such as economics, cybersecurity, climate change and trade. The tone reflected American wariness about China's prominence on the world stage," Taylor said.

Charles Ebinger, a senior fellow at the Brookings Institution, said it's "good to see climate change mentioned not only as an environmental risk, but a national security risk."

A Gallup poll showed that Obama's averaged a 42.6 percent job approval rating throughout his six full years in office, which ended Monday. Although the ratings in recent weeks have been higher, the sixth-year average is still his lowest yearly rating to date.

chenweihua@chinadailyusa.com