Tackling black carbon, ozone could yield big benefits

Written by Marion Davis

Tuesday, 14 June 2011 16:38

Smog over Los Angeles, California. FLICKR/ColetteSimonds

Complementary action to curb ‘soot’ and ‘smog’ pollution, a new report released in Bonn shows, could help limit global temperature rise to 2°C or less – and save millions of lives.

The report, launched June 14 at the UN Climate Conference, evaluates the scientific research on “short-lived climate forcers” such as black carbon, ground-level ozone and methane and finds that tackling them could slow near-term global temperature increases and bring immediate public-health and agricultural benefits.

SEI coordinated the new assessment, sponsored by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO).



Unlike carbon dioxide (CO2) which can remain in the atmosphere for centuries, black carbon only persists for days or weeks, the report notes, and there are several known strategies to reduce its emissions.

In terms of climate, the study finds, rapid action to curb black carbon deposition could significantly cut the risk of “amplified global climate change” linked with extensive loss of Arctic ice. It could also slow warming in the Arctic by two-thirds and reduce losses of mountain glaciers.

Curbing black-carbon emissions could also prevent close to 2.5 million premature deaths per year worldwide by 2030, the study finds – a large share of them in Asia. In addition, countries would see improved respiratory health and fewer hospital admissions and lost work days.

Cutting ground-level ozone, meanwhile, could also contribute to reduced crop damage equal to 1 to 4 per cent of the annual global maize, rice, soybean and wheat production, the study shows.

“The biggest impacts of emission reductions are seen in the regions where action is taken,” says Johan Kuylenstierna, director of SEI’s York Centre and scientific coordinator and lead author of the report. “This is especially true for public health, but also follows for crop yields and regional climate impacts.”

An international effort
The report, released at a major UN Framework Convention on Climate Change (UNFCCC) meeting, was compiled by an international team of more than 50 researchers chaired by Drew Shindell of the U.S. National Aeronautics and Space Administration (NASA-GISS).

Along with Kuylenstierna, the SEI  team included Kevin Hicks and Harry Vallack, also lead authors, and Lisa Emberson, coordinating lead author of the chapter on impacts.

“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,” says Achim Steiner, UN Under-Secretary General and executive director of UNEP.

“This assessment underlines how the science of short-lived climate forcers has evolved to a level of maturity that now requires and requests a robust policy response by nations,” he adds. “The experts spotlight how a small number of emission reduction measures – targeting, for example, recovery of methane in the coal, oil and gas sectors through to the provision of cleaner burning cook stoves; particle traps for diesel vehicles and the banning of open burning of agricultural wastes – offer dramatic public health, agricultural, economic and environmental benefits.”

The study stresses that while action on short-lived climate forcers could play a key role in limiting near-term climate change, immediate and sustained action to cut back CO2 is crucial if temperature rises are to be limited over the long term.

Read the UNEP press release on the report.
Read the SEI press release.
Read the Summary for Decision Makers (external link; pdf, 2mb).