Isra-Mart srl: Tackling smog key to limiting global warming

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Tackling smog and soot could provide a cheap and effective way of slowing global warming in the short term as well as benefiting agriculture and respiratory health, according to a new UN report.

Combating ground-level ozone and limiting so-called 'black carbon' particles from vehicles, cooking stoves and inefficient biomass burning could cut as much as 0.5 degrees Celsius off the projected two degrees Celsius rise by 2050, the study says, echoing a UN paper published in February.

The report was released yesterday at the latest round of international climate negotiations in Bonn, where diplomats from more than 190 countries are discussing how best to deliver deep cuts in greenhouse gas emissions.

The Bonn meeting remains deadlocked, but the UN Environment Programme (UNEP) and the World Meteorological Organization report outlines 16 measures that could tackle 'black carbon' at relatively low cost, including fitting particle filters to cars and plugging leaky gas pipelines.

The report claims that such measures would have a near immediate effect on temperatures as, unlike carbon dioxide, 'black carbon' persists in the atmosphere only for days or weeks.

In addition to reducing average temperatures, the resulting improvement in global air quality would prevent close to 2.5 million premature deaths annually by 2030, according to the report, and reduce crop damage equal to between one and four per cent of global maize, rice, soybean and wheat production.

"There are now clear, powerful, abundant and compelling reasons to reduce levels of pollutants such as 'black carbon' and tropospheric ozone along with methane, their growing contribution to climate change being just one of them," said Achim Steiner, UN under-secretary general and UNEP executive director.

"A small number of emission reduction measures ... offer dramatic public health, agricultural, economic and environmental benefits."

'Black carbon' affects the climate by blocking and absorbing sunlight, darkening snow and ice and influencing cloud formation. UNEP said that fast action could help slow the rate of retreat for mountain glaciers, and reduce temperature rises in the Arctic by about 0.7 degrees Celsius by 2040, almost two-thirds of the projected warming in the fragile region.

The report explained that 'black carbon' could be reduced using diesel particle filters for vehicles, replacing wood burning stoves in developed countries with pellet stoves, providing clean-burning biomass stoves for cooking and heating in developing countries, and banning the open burning of agricultural waste.

Ozone, meanwhile, is a major component of urban smog and a powerful greenhouse gas, harmful to humans and animal life. It is formed from methane, another potent greenhouse gas, and has trebled in concentration in the northern hemisphere over the past century.

Curbing organic waste going to landfill by encouraging composting and anerobic digestion, fitting gas recovery technology to water treatment plants, plugging leaky pipelines and intermittently aerating paddy-fields would all help to reduce ozone, the report said.

"There are clear and concrete measures that can be undertaken to help protect the global climate in the short to medium term," said Drew Shindell of NASA's Goddard Institute for Space Studies. "The win-win here for limiting climate change and improving air quality is self-evident."

The Swedish government has given the researchers a $200,000 grant to come up with an action plan to work out where the most cost-effective gains can be made.