<i> By Fred Pearce, Environment Consultant, The New Scientist</i>

But this magical solution - using cheap and simple measures to curb air pollutants like diesel fumes and soot from open fires - isn't even on the agenda here at the climate conference.

The UN Environment Programme's director Achim Steiner told a fringe meeting here that his organisation has drawn up a plan for purging the atmosphere of "short-lived climate forcers", which may stay in the air for only a few days. "It may be the best hope we have to stay within two degrees of warming," he said.

He said the plan was not an alternative to curbing carbon dioxide. But it could prevent about 0.4 °C of global warming - or around half of the expecting warming between now and 2050.

By delivering a big short-term cooling effect, it could buy the world a couple of decades to get its act together on carbon dioxide.

UNEP has studied three short-term warming agents: black carbon in soot from fires and diesel engines; methane from gas pipelines, landfills and other concentrated sources; and ozone, a by-product of atmospheric reactions involving methane.

Methane, a greenhouse gas, lasts in the atmosphere for about a decade, and black carbon and ozone for about a week. Only methane is covered by the existing Kyoto Protocol to combat climate change.

UNEP's 16-point plan includes providing fuel-efficient, low-pollution stoves for the three billion people who still cook over an open fire, putting filters on diesel exhausts, reducing leaks from gas pipelines, and replacing traditional brick kilns.

A number of climate scientists have previously identified black carbon in soot and methane as the best focus for a cheap and quick hit against climate change, notably NASA's Jim Hansen.

But UNEP's chief scientist Joseph Alcamo says half of what his organisation proposes would be self-funded, largely by cutting the use of fuels such as natural gas or firewood. And it would all bring huge benefits in public health and food production.

Indoor air pollution from soot and fumes from fires kills an estimated two billion people each year, mostly women and children who suffer lung diseases caused by cooking over an open stove. More than a billion more people die from the effects of dangerous outdoor pollutants, like soot from diesel emissions and industrial emissions like brick kilns.

Credible measures using simply technologies could cut these emissions by 75 per cent, Alcamo says.

Black carbon absorbs sunlight and radiates energy that warms the air around. In icy regions like the Arctic and Himalayas it also darkens white surfaces, causing both warming and melting. Because much of its warming effect occurs within the country where it is produced, countries will see a direct local cooling from curbing its emissions.

So the plan should require no convoluted negotiations for a global treaty, just national action, said Alcamo. The plan to act on these forgotten planet warmers has added urgency because of the failure of talks here in Durban to deliver a global deal on carbon dioxide, Steiner said. "I can't see anything in these negotiations that will prevent warming beyond two degrees."

"To do that will require the world's carbon dioxide emissions to peak by 2020, but it now looks as if we may not even have an agreement in force until 2020. We have to find a way to break through the impasse. Action on short-lived climate forcers can buy us back some of the time we have lost."

Lena Ek, the Swedish environment minister, agreed "this is possibly the only way of slowing down climate change in the medium term."