The United Nations says national pledges to cut greenhouse gases under the Copenhagen Accord fall short of what is needed to limit a rise in global temperatures of two degrees Celsius.
The UN has unveiled the most thorough assessment yet of the accord, which is the only global climate deal on the table.
Since the troubled climate talks in Denmark last year, 140 nations have signed up to the accord and the next round of negotiations get underway in Mexico next week.
But the UN report has found national promises to cut greenhouse gases fall short of what is needed.
The head of the UN’s Environment Program, Achim Steiner, says the report is cause for concern.
“The science is basically giving us an idea of how much carbon dioxide (C02) or carbon dioxide equivalent this planet can deal with if you want to stay on this pathway of keeping a two-degree warming scenario for the world and not go beyond it,” he said.
“What the report has tried to do, by bringing together the best modelling centres around the world, is to determine what is the range of emissions that we would need to reach by the year 2020 to be able to say we have a chance to keep the world in a two-degree scenario. It also says what happened in Copenhagen in terms of the voluntary pledges.
“And if you add all of them together and were to implement them, you’ll get, probably get within 60 per cent of what we need to achieve to have that chance to sort of be on the pathway to a two-degree world.
“If we do nothing we’ll probably be at 56 gigatonnes [of C02] by the year 2020 and that obviously is something that should make us all sit up and look very carefully at what happens next.”
Mr Steiner says many nations have so far failed to live up to their Copenhagen promises.
“I think that the world certainly has cause for concern because the climate change nations post-Copenhagen certainly have not exactly taken off in the direction that we had all hoped,” he said.
“On the other hand, many countries are, in fact, acting on global warming. They are acting in terms of energy efficiency, new technologies, renewable energy, transport and mobility.
“So, yes, we’ve seen many examples right across the global economy where action on climate change is occurring. But the factor of mutually assured success, which is inherent in this notion that we address climate change collectively, is certainly still a weak one.
“We will see in Cancun whether the world can get confidence in each other again that the pledges and commitments of Copenhagen don’t just remain theory.
“And these numbers certainly demonstrate why it would be worthwhile and certainly how doable it is and what remains to be done to really be successful in a global climate partnership.”