The aftermath of United Nations climate change summits is becoming depressingly familiar.

As with Copenhagen a year ago, so it is now with Cancun. Much is being made of the small steps agreed upon after two weeks of tortuous negotiations and how these can be built upon at the next meeting a year hence.

Little is said of yet another failure to arrive at a legally binding pact that obliges the world's major emitters to meet serious greenhouse-gas targets. Nor is it mentioned that the obstacles to such an agreement remain firmly in place.

The talks in Mexico approved a deal that creates a Green Climate Fund to raise US$100 billion ($134 billion) a year by 2020 to help poorer nations with low-carbon development, and restated a target of limiting a rise in average world temperatures to below 2C over pre-industrial times.

There is also an outline for funding developing nations to reduce deforestation. Such moves are welcome as a means of channelling aid to the poor, who are acutely affected by climate change, and protecting rainforests, which soak up carbon.

But they represent relatively little when compared with the failure to make progress on extending the Kyoto Protocol, the one international pact containing legally binding emissions cuts. Its commitment period, which applies to every developed country except the United States, expires at the end of 2012.

Kyoto, in fact, accounts for less than 25 per cent of global emissions, but it is hugely important as a symbol. Its signing reflected a widespread recognition of the need to address climate change. Every conference that passes without consensus on its future heightens the chance of it lapsing without a successor to take its place.

Many of the biggest non-European Kyoto signatories are reluctant to agree to a second commitment if the world's biggest and fastest-growing emitters remain outside it. Cancun did nothing to ease their concerns. China, which effectively torpedoed the Copenhagen summit with its unwillingness to accept targets, remained as obstructive as ever.

Meanwhile, hopes that the Obama Administration would bring the US into the global mainstream have been undermined by the Republican success in the mid-term elections. Together, China and the US are responsible for more than 40 per cent of the world's emissions.

For all the talk of a renewed sense of goodwill and purpose, it is, therefore, difficult to see how the document signed at Cancun represents real progress. The rift between developed and developing nations on how to extend or replace the Kyoto Protocol has not been healed. The latter still insist rich nations must extend Kyoto before they agree to a less onerous deal. Battle will recommence in Durban in a year.

Indeed, the most significant momentum from Cancun may have came from officials in both the public and private sectors who announced they had decided to go their own way in reducing emissions. Denmark, for example, is joining South Korea in helping countries develop eco-friendly technologies. But such initiatives go only so far.

The reality is that most nations will be reluctant to take more than modest unilateral action or enter bilateral deals if that means losing manufacturing capacity or suchlike to countries that make no such effort to reduce emissions.

The ultimate answer still lies in a recognition that climate change is a global issue and that a global agreement is necessary to tackle it. If the optimists are correct, Cancun may just have moved the world along that road.

If they are not, we will soon, out of necessity, be placing the emphasis on adapting to a warmer world. The time available to forestall the problem will have run out.