Soot almost as bad as CO₂ for global warming

US scientists have said switching anti-global warming efforts to tackling the production of soot would offer a quicker return than cutting CO₂ emissions.

According to US scientists, enormous damage is being done by soot, which is being created by the combustion of fossil fuels and as an indirect result of deforestation, among other factors.

They claim that soot - or black carbon to give it the scientific name - is the second biggest cause of global warming behind CO2, causing 60 percent of the warming effect of CO₂.

Professor Greg Carmichael, of the University of Iowa and Professor V Ramanathan, of Scripps Institution of Oceanography, argue that tackling the emissions of soot offers a far quicker chance to address global warming than trying to reduce CO₂ emissions. They said this is because soot has a much shorter lifetime than CO₂, which can hang about for around 100 years.

The scientists, who published their research in the Nature Geoscience journal on Sunday, estimate that soot will have a surface warming effect on the Earth of "about 0.5 to 1 deg C". They say its energy effect is around 0.9 watts per square metre, substantially more than the 0.2 - 0.4 watts per square metre estimated by the Intergovernmental Panel on Climate Change.

Most of the world's soot was created by Europe and North America until the 1950s, but since then the two regions have been overtaken in their contribution by nations in the tropics and the Far East.

In less developed countries, soot is created by cooking with biofuels such as wood, dung and crop residue. It's also produced by so-called open biomass burning, which is associated with deforestation and burning crops. ®