The five-page-long text, which only "recognises" the need to limit global temperatures to rising no more than 2 degrees Celsius above pre-industrial levels, but does not require that this happen, was itself only "recognised" by the 193 countries attending the Copenhagen summit and not approved by them.

Most developing countries - the hardest hit by global warming - have been pushing for an upper limit of 1.5 degrees as 2 degrees of average change still results in growth of up to four degrees in some parts of the planet.

No emissions reduction ambitions were delineated for the key year of 2020, and even a previous target of cutting CO2 emissions by 80 percent by 2050 was abandoned. This came as a surprise to many observers, as commitments to quite deep cuts long after the current generation of politicians has left the stage have been nowhere near as controversial as discussions over shorter-term goals.

The European Union in the end did not make the leap from a 20 percent cut in emissions to 30 percent, reckoning that the other reduction offers on the table were not sufficiently ambitious.

While the scientific consensus is that at a minimum, CO2 must be reduced by developed countries by between 25 and 40 percent, the reduction pledges made by global powers amounted to between 13 and 19 percent. According to a late-hour analysis by the UN leaked to the press on the eve of the final talks, this would result in a temperature change of three degrees.

Despite the EU decision to hold back its 30 percent offer, European Commission President Jose Manuel Barroso insisted such a move was not ruled out at some point in the future. "This is not the final say. We need to keep working on this," he said.

The Copenhagen deal sets no year for a peak in emissions, although its implementation is to be reviewed by 2015.

The accord also "sets a goal" of delivering $100 billion a year to developing countries to help them deal with the effects of climate change and to move towards a low-carbon development path.

But this headline figure includes no reference to how much will come from government coffers and how much from funds that would flow anyway via normal market mechanisms.

Emerging nations such as China are to monitor their emissions reduction efforts and report to the UN every two years. The US and the EU to a lesser extent have been pushing for the richer developing nations to agree to mechanisms that could verify whether cuts had in fact been achieved.

Fredrik Reinfeldt, Sweden's prime minister and holder of the EU's six-month rotating presidency, admitted the conclusion to the conference will not counter global warming.

"Let's be honest. This is not a perfect agreement. It will not solve the climate threat," he said.

For a summit that was in many ways, until the appearance of US and Chinese leaders, dominated by the European Union, both as participant and through the Danish presidency of the UN process, the result is a particular embarrassment for the bloc.

European Commission President Jose Manuel Barroso said the accord was "a positive step but clearly below our ambitions," while adding: "I will not hide my disappointment."

Developing countries were more scathing. Lumumba Di-Aping, the chief negotiator of the G77 group of nations called the end product of the two-week conference "the lowest level of ambition you can imagine. It's nothing short of climate change scepticism in action. It locks countries into a cycle of poverty for ever."

Fury, disappointment

Mr Di-Aping called the pact "a solution based on values, the very same values in our opinion that funneled 6 million people in Europe into furnaces." The rich north had "asked Africa to sign a suicide pact, an incineration pact, in order to maintain the economic dominance of a few countries."

Bolivia's UN ambassador, Pablo Solon, was furious that the accord had been drafted without the participation of most of the world's countries: "This is completely unacceptable. How can it be that 25 to 30 nations cook up an agreement that excludes the majority of the 190 nations?" he asked.

Green and development NGOs took all developed countries to task but singled out the United States, which failed to up its emissions reduction beyond 17 percent on 2005 levels, which amounted to a cut of just four percent when using the international benchmark year of 1990.

"Unless this outcome is improved in the coming months the US will have signed the death warrant for those most vulnerable to climate change – people in small island states, Africa and the least developed countries," said Rashed Titumir of UK-based Action Aid.

"This summit has been in complete disarray from start to finish, culminating in a shameful and monumental failure that has condemned millions of people around the world to untold suffering," said Tim Jones, of the World Development Movement. "The leaders of rich countries have refused to lead. They have been captured by business interests at a time when people need leaders to put justice first."

As the dust was settling on the conference, some worried that the north would only offer climate cash to those countries that signed onto the accord. UK environment minister Ed Miliband told developing countries to sign on to the deal "so the money can start flowing."

"The US appears to be more interested in saving face than saving the planet," said Friends of the Earth executive director Andy Atkins. "They are now using strong-arm tactics to bully the developing world into backing a plan that completely undermines the existing UN process."

"This summit has been a complete failure - the climate accord should be sent to the recycling bin," he added, referring to the Danish capital as "Brokenhagen."