Cutting black carbon, methane and ground level ozone boosts food security and saves millions of lives

December 2nd, 2011 by United Nations Environment Programme

A package of 16 measures, if fully implemented across the globe, could save close to 2.4 million lives annually, avoid crop losses amounting to 32 million tonnes annually and deliver near-term climate protection of about 0.5° C by 2040.

Implementing these measures could help keep global temperature rise below the 2° C target, at least until mid-century.

The measures targeting, short-lived climate forcers (SLFCs) — black carbon which is a major component of soot, methane and tropospheric ozone, are outlined in a new report compiled by the UN Environment Programme (UNEP) and involving an international team of experts including researchers from the International Institute for Applied Systems Analysis, (IIASA) based in Austria.

(click on report cover to go to UNEP download page)

The report, Near-term climate Protection and Clean Air Benefits, employs the International Institute for Applied Systems Analysis (IIASA) developed GAINS model (Greenhouse Gas and Air Pollution Interactions and Synergies Model) to identify the measures and calculate the costs of implementing these measure at a country level.

Of the 2000 possible mitigation measures available, the GAINS model identified approximately 130 that would achieve a reduction in global warming, with the top 16 measures realizing nearly 90 per cent of the maximum reduction potential in equivalent CO2 emissions by 2030.

The report emphasizes that fast action on short-lived climate forcers will not be able to keep global temperature rise to under 2°C by the end of the century, unless governments act decisively on the principle greenhouse gas, carbon dioxide (CO2).

The report, funded by the Government of Sweden, estimates that around half of the black carbon and methane emission reductions can be achieved through measures that result in cost savings over the lifetime of the investment. This is because some of the measures—such as recovering rather than emitting natural gas during oil production—allow the methane to be harvested as a clean source of fuel.

Cutting black carbon emissions by, for example, replacing inefficient cook stoves and traditional brick kilns with more efficient ones, also cuts fuel costs for households and kiln operators. Black carbon, together with other components of particulate matter – emitted as a result of inefficient burning from a wide range of sources, including cook stoves and diesel engines – is a major cause of premature deaths, resulting from outdoor and indoor pollution.

The report points to other economic, social and environmental benefits that are not included in the overall cost-estimates of this assessment. These include:

  • Upgrading wastewater treatment works will help cut emissions of methane, while improving sanitation and water quality.
  • Recovery of coal mine methane – carried out for occupational safety reasons as well as for the economic value of methane as a clean-burning energy source – will have significant climate and health benefits.

The report builds on some ten years of scientific research, first, through the UNEP Atmospheric Brown Cloud project, and more recently via assessments by UNEP and the World Meteorological Organization (WMO).

In June this year, UNEP and the WMO released their Integrated Assessment of Black Carbon and Tropospheric Ozone report, underlining the likely health, agricultural and climate benefits of fast action on these pollutants.

The June report also spotlighted the link between methane emissions and the formation of tropospheric ozone, concluding that methane is contributing by about 50 per cent to increases in background ozone concentrations world-wide. This, in part, explains why the concentrations of tropospheric ozone in the northern hemisphere have tripled over the past 100 years. Indeed, tropospheric ozone has become the third most important contributor to man-made climate change, after carbon dioxide and methane itself. Tropospheric ozone also reduces crop yields and damages human health, when inhaled.

Black carbon is also likely to heat up the atmosphere and, when deposited onto ice caps and glaciers, can accelerate melting because less sunlight is reflected back into space. Fast action on short-lived climate forcers could significantly cut the rate of warming in the Arctic and reduce projected warming in 2040 by 0.7° C, with important implications for the lives and livelihoods of Arctic peoples, biodiversity and global sea-level rise.

At the report’s launch in London Achim Steiner, UN Under-Secretary General and UNEP Executive Director, said: “The scientific case for fast action on these so-called ‘Short-Lived Climate Forcers’ has been steadily built over more than a decade—the question governments have been asking over recent months is what are the options and priorities for action and the likely costs and benefits in order to advance a response to rapidly manage these substances.”

“This report provides that analysis and offers pathways and policies that may allow nations, acting nationally, regionally and globally, to achieve some remarkable gains in terms of a transition to a low emission, resource efficient Green Economy over the near term.”

“For some countries the most important benefits result from cost-effective improvements in air pollution and reduced illness and loss of life—black carbon, for example, could be controlled under national and regional air quality agreements. Other countries are also recognizing the food security benefits in terms of reduced crop damage in a world of seven billion people,” said Mr. Steiner.

“For others, it may be the regional and global climate benefits that are uppermost in their minds—whatever the motivation, this report presents the costs and the benefits that can play their part towards a sustainable 21st century as governments head towards Rio+20 in June 2012,” he added.

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