Governments could slow global warming dramatically, and buy time to avert disastrous climate change, by slashing emissions of one of humanity's most familiar pollutants — soot — according to Nasa scientists.

A study by the space agency shows that cutting down on the pollutant, which has been largely ignored by climate scientists, can have an immediate cooling effect — and prevent thousands of deaths from air pollution.

At the beginning of attempts to negotiate a treaty to replace the Kyoto Protocol, the soot removal proposal offers hope of a rapid new way of tackling global warming. Governments have long experience in acting against soot.

Cutting its emissions has an instant effect, because it falls out of the atmosphere, unlike carbon dioxide which remains there for over 100 years.

The study — from Nasa's Goddard Institute for Space Studies, — concludes that tackling the pollution provides “substantial benefits for air quality while simultaneously contributing to climate change mitigation”.

Black carbon, the component of soot that gives it its colour, is thought to be the second largest cause of global warming after carbon dioxide. While in the air, it is spread globally by the wind, and helps to heat the atmosphere by absorbing and releasing solar radiation.

Taking quick action is quite simply our only near-term option

And when it falls out it darkens snow and ice, at the poles or high in mountains, reducing its ability to reflect sunlight. As a result it melts quickly, and exposes more dark land or water which absorbs even more energy, and so increases warming. The bad news — as the Washington-based Institute for Governance and Sustainable Development says — is that soot is causing global warming to happen faster than expected. Its president, Durwood Zaelke, says “black carbon is exacerbating the climate situation”: “Taking quick action is quite simply our only near-term option.”

Rich countries have already reduced emissions of black carbon from burning fossil fuels since the 1950s. The health benefits of a worldwide cut could be massive. Soot contains cancer-causing chemicals and can also cause respiratory and heart diseases. It causes two million deaths in the developing world each year when emitted from wood-burning stoves in poorly ventilated houses.

Tackling these two health crises, the Nasa concludes, would also be the most effective short-term way of slowing climate change. Its says the “strongest leverage” on reducing global warming would be achieved by “reducing emissions from domestic fuel burning” in developing countries and by “reduction in surface transport emissions”, especially from diesel engines.

In both cases solutions are known. Cookers using solar energy or biogas eliminate smoke. And last month California brought in measures to force trucks to fit filters to reduce diesel soot emissions by 85 per cent.