"At this point, everyone should be extremely concerned about what we will walk away with from Durban," Achim Steiner, UNEP's executive director, told EurActiv.
"Without a global climate agreement, we will never be able to achieve the levels of emissions reductions that are needed and with every year that passes, the time window is getting narrower," he said.
The latest International Energy Association figures show that greenhouse gas emissions soared by a record amount last year to 30.6 gigatonnes, the highest carbon output in history.
Trying to achieve CO2 emissions cuts in a shorter future timeframe would pose "a much greater risk to the global economy, national economies and to human wellbeing," Steiner said.
Durban objectives
The first goal of the Durban meeting will be securing a global climate agreement to replace the Kyoto Protocol's first commitment period, which ends in 2012.
But the EU's climate action commissioner, Connie Hedegaard, and the US's lead climate negotiator, Todd Stern, have both dismissed the chances of agreeing a legally binding deal this autumn.
Behind the scenes, Jacob Zuma's government in South Africa has come in for heavy criticism in Brussels for a lack of leadership, drive and clarity in its pre-summit preparations.
Commissioner Hedegaard told EurActiv that whatever happened in Durban, EU legislation would ensure that from 2013, "we will only have offsetting for the least developed countries, not for emerging economies like today".
"So there's already a major transition in the pipeline," she continued, "but that is one of the things that we will use to discuss with our partners in Durban: they want this system to continue. OK. What will they give in return?"
Outstanding issues
Outstanding issues in Durban will include numbers and timetables for legally-binding emission cuts, details of a $100 billion per year Green Climate Fund for aid and mitigation, and ways of categorising 'developed' and 'developing' countries for climate targets.
Attempts by developing countries to reopen the debate on strengthening the current global warming target from 2°C to 1.5°C have been supported by the executive secretary of the United Nations Framework on Climate Change, Christiana Figueres.
Steiner acknowledged that failure to reach agreement would not prevent "incremental progress" and efforts to bridge a global climate policy. But it would still cause "major disappointment and frustration across the board," in his view.
"I think that the historians will one day write off the decade of 2010-2020 as one of the tragic moments of indecision," he said, "of an international community and a world economy that was perfectly capable of moving to another level of carbon emissions trajectories but didn't choose to do so for what will then seem, perhaps, completely extraneous reasons".
The world's largest historic emitter of CO2, the US, has never ratified the Kyoto Agreement, while the biggest contemporary polluter, China, is currently excluded as a developing country.
Because of this, Japan, Russia and Canada have refused to sign a Kyoto successor agreement which they say will only cover about 30% of global emissions.
Arthur Neslen
