World leaders yesterday defended the much-criticised climate deal they struck at a UN summit as a key step in the fight against global warming despite its lack of targets to curb emissions.
Newspapers widely branded the accord a failure and experts such as the head of a Nobel Peace prize-winning climate panel said "urgent" action was now needed.
US President Barack Obama acknowledged that all of the world's polluters would quickly have to do more, but German Chancellor Angela Merkel said the critics would only hold up the battle against rising temperatures that threaten devastating floods, storms and drought.
Mr Obama returned to the White House and said "extremely difficult and complex negotiations" had been needed in Copenhagen.
"This breakthrough lays the foundation for international action in the years to come."
But even the US leader said "we will have to build on the momentum" and get the US Congress to pass mandatory cuts in greenhouse gases blamed for global warming.
Mrs Merkel hit back at critics saying Copenhagen was "a first step towards a new world climate order, nothing more but also nothing less", she told Bild am Sonntag newspaper.
"Those who are only putting Copenhagen down are helping those who want to blockade rather than move forward."
Germany will host a follow-up meeting of environment ministers in Bonn in June, ahead of another summit in Mexico City next December.
The Danish chair of the UN climate summit, Connie Hedegaard, said yesterday she thought it would be difficult to gather together so many world leaders again for a new conference, though the effort must be made.
The Copenhagen Accord, only passed by a procedural motion after two weeks of tense negotiations, has been widely condemned as a backdoor deal that excludes the poor and dooms the world to disastrous climate change.
The agreement was assembled by the leaders of the United States, China, India, Brazil, South Africa and major European nations, after it became clear the 194-nation summit was in danger of failure.
Danish Prime Minister Lars Loekke Rasmussen said the agreement reached in Copenhagen was "better than nothing" and "not a bad result".
China, the world's top polluter, has given the warmest welcome to a summit that experts say it has benefited from by making the fewest concessions.
"With the efforts of all parties, the summit yielded significant and positive results," Foreign Minister Yang Jiechi said in a statement.
The summit set a commitment to limit global warming to two degrees Celsius, but did not spell out the important global emissions targets for 2020 or 2050 that are the key to holding down temperatures.
It also promised $100 billion for poor nations that risk bearing the brunt of the global warming fallout, but has not given a fixed payout plan.
So far, the United States has promised to contribute $3.6 billion in climate funds for the 2010-2012 period, with Japan contributing a total of $11 billion, and the European Union $10.6 billion.
However, the Council of Europe criticised the Copenhagen accord as a "missed opportunity" for failing to take "concrete decisions", which threatens food security and access to water or land for people who could "swell the ranks of climate refugees", said Lluis Maria de Puig, head of the Council's parliamentary assembly.