By Alister Doyle, Environment Correspondent
BONN (Reuters) - Tighter limits on soot and smog provide a quick and easy way to fight global warming while protecting human health and raising crop output, a U.N. study said on Tuesday.
It outlined 16 measures, ranging from plugging leaky gas transport pipelines to improving wood burning stoves, to limit "black carbon" -- soot -- methane and tropospheric ozone, which is a greenhouse gas that is a big component of smog.
"A small number of emission reduction measures ... offer dramatic public health, agricultural, economic and environmental benefits," Achim Steiner, head of the U.N. Environment Programme, said in a statement of the report.
The study, urging actions beyond a normal focus on curbing carbon dioxide, the main greenhouse gas from human activities, said the recommended actions could lop 0.5 degree Celsius (0.9 Fahrenheit) off rising temperatures.
That would help the world reach a goal adopted by 200 nations in Mexico last year of limiting the rise to below 2 degrees C above pre-industrial times. World temperatures have already risen by about 0.8 degree C, and are headed upwards.
Even before accounting for wider benefits, there were often low costs or even savings.
"For many of the measures, especially the methane ... there are cost savings," Johan Kuylenstierna of the Stockholm Environment Institute told a news conference in Bonn on the sidelines of June 6-17 climate talks.
To reduce methane, it called for better ventilation of coal mines, better use of gas associated with oil and gas production, reduced leaks from pipelines, better recycling of waste and reforms to agriculture such as better management of rice paddy fields.
To limit black carbon, it called for adoption of diesel particle filters at European Union standards, cleaner-burning stoves and a ban on the open-field burning of farm waste.
Michel Jarraud, head of the World Meteorological Organization, said the WMO would step up monitoring of the impact of the air pollutants on the climate.
The report expanded on preliminary findings from February.
It reiterated that less air pollution could avoid 2.4 million premature human deaths a year and the annual loss of 52 million tonnes, or about 2 percent, of world production of maize, rice, soybean and wheat.
The researchers, backed by a $200,000 grant from Sweden, would work out an action plan to try to work out costs and areas where the biggest gains could be made.
They also said benefits would be felt strongly in ice-covered regions of the Arctic or the Himalayas. When soot settles on ice, it darkens the surface and allows it to soak up more heat, adding to a thaw that further stokes global warming.
The report estimated that the measures could slow warming in the Arctic by about 0.7 degree Celsius by 2040, almost two-thirds of the projected warming in the region.
The report said it focused on heat-trapping pollution. Some polluting particles have the opposite impact of reflecting sunlight into space and so contributing to cooling.
(Editing by Janet Lawrence)
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