Back in Washington from his trip to the U.N.-sponsored meeting in Denmark, Mr. Obama said (Saturday) the world needs to "build on the momentum" of the new accord. He pledged to step up development of the "clean-energy economy" in the United States, which he said has dual environmental and economic benefits.
Environmentalists and less-developed nations criticized parts of the Copenhagen accord and gave it only weak support. U.N. Secretary General Ban Ki-moon acknowledged that a lot of work is yet to be done, but he hailed the compromise effort as a definite step forward.
Delegates at the Copenhagen conference agreed only to "take note" of the non-binding accord - a verdict that falls short of full endorsement.
The accord was the product of marathon negotiations by Mr. Obama and leaders from four nations with a key role in the climate-change meetings: China, India, Brazil and South Africa.
The accord says greenhouse-gases and other emissions by all nations must be reduced enough to prevent average global temperatures - the key index of global warming - from rising more than 2 degrees celsius over temperatures from the pre-industrial era. However, it does not set specific emissions guidelines for achieving that goal.
At present, average annual temperatures worldwide are 0.7 degrees celsius above preindustrial levels, and many scientists contend the world is on course to exceed the 2-degree target limit by nearly 100 percent (3.9 degrees) during this century.
The Copenhagen accord also commits rich nations to contribute $30 billion to a fund to help developing nations curb their emissions over the next three years. They set a goal of increasing funding up to $100 billion by 2020.
The agreement that Mr. Obama and other leaders announced late Friday was reached in the final session of a two-week conference plagued by disagreements between rich and poor countries over emissions targets and financing.
Delegates from the tiny Pacific island nation Tuvalu and several Latin American nations said the agreement was insufficient, and they complained that the final negotiations excluded many countries.
In a controversial comment criticized by many at the conference, a representative from Sudan likened the deal to the Holocaust, saying that unless stronger steps are taken to reduce global warming, many Africans will die.