Copenhagen Accord, a political statement attempting to give the United Nations Climate Change Conference an outcome but without any legal binding, is now seriously challenged by the Group of 77, even though US President Barack Obama deemed it "a meaningful breakthrough".

The accord has not gone through "a democratic process" and was a deal between a couple of dozens of countries that do not take into account of the concerns of the most developing countries, Lumumba Stanislaus-Kaw Di-Aping, Chair of Group of 77, told reporters.

The accord leaves several key elements for the nations to work out before February 1 next year.

"The biggest challenge, turning the political will into a legally binding agreement, has moved to Mexico," said Kim Carstensen, the leader of WWF Global climate initiative, as the accord mandates that the nations continue negotiations on the Long-term Cooperative Action and amendments to Kyoto Protocol, two legally-binding documents that most countries have come to Copenhagen to work on with the hope that the two documents will guide the global efforts in mitigating global warming.

Recognizing the level of national promises for mitigating climate change, Carstensen said the pledges tabled by the nations still add up to 3 degrees Celsius or more even though the Intergovernmental Panel for Climate Change warns that stringent efforts should be made to limit the global warming below 2 degrees Celsius.

Kumi Naidoo, Greenpeace International executive director, said that the accord is "not fair, not ambitious and not legally binding."

"The job of world leaders is not done," he said.

He noted the a number of developing countries "showed a willingness to accept their share of the burden to avert climate chaos."

However, "the blame for failure mostly lies with the rich industrialized world, countries which have the largest historic responsibility for causing the problem," Naidoo said.