Lesley JantarasamiPresentation to the National Tribal Forum

May 22, 2012

Overview of EPA’s Report to Congress on Black Carbon

What is Black Carbon?

• Black carbon is the most strongly light-absorbing component of particulate matter (PM)

• Formed by incomplete combustion of fossil fuels, biofuels, and biomass; a major component of “soot”

• Always emitted with other types of particles and gases, including sulfates, nitrates and organic carbon, which generally reflect light

• Remains in atmosphere days to weeks

• Principally a regional pollutant2

EPA’s Report to Congress on Black Carbon

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• In October 2009, Congress requested that EPA conduct a comprehensive study on BC to evaluate domestic and international sources, and climate/health impacts

• EPA completed this report on March 30, 2012

• Available online at: www.epa.gov/blackcarbon

Health and Environmental Effects of Black Carbon

• BC contributes to the adverse impacts on human health, ecosystems, and visibility associated with PM2.5

• Exposures to PM2.5 are associated with a broad range of human health impacts, including respiratory and cardiovascular effects and premature death

Brick Kiln in Kathmandu

Traditional Cookstove in India 4

• BC affects climate by:

– Directly absorbing light ( warming)– Reducing the reflectivity of snow and ice ( warming)– Interacting with clouds (uncertain cooling and/or warming)

• Net climate influence of BC is not yet clear, though most estimates indicate it is warming.

Climate Effects of Black Carbon

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Darker Ice Absorbs

Black Carbon Effects on Snow and Ice

• BC deposition on mountain glaciers and snowpack has a strong feedback that accelerates melting, with implications for freshwater availability and seasonal droughts.

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• Arctic sea ice melting may be accelerated by BC emissions from northern latitudes.

Black Carbon Effects on Precipitation

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Atmospheric Brown Cloud

• Particle pollution affects the processes of cloud and rain droplet formation, but these interactions are not well understood.

• BC has been linked to the formation of pollution plumes known as Atmospheric Brown Clouds, which affects regional rainfall (monsoon) patterns in South Asia.

Black Carbon Effects on Sensitive Regions

• Certain regions of the world are more sensitive to or more likely to be affected by BC’s warming/melting effects.

Arctic• Sensitivity due to transport and deposition of BC on snow and ice

Asia / Himalayas• Sensitivity due to existing high levels of particle pollution in the

region

8Deposition on Snow/Ice

Estimated Global Black Carbon Emissions

• Global BC emissions: ~8.4 million tons in 2000.

• The majority (75%) comes from Asia, Africa and Latin America.

• Largest sources are open biomass burning and residential sources.

• Total global BC emissions are likely to decrease in the future, but developing countries may experience emissions growth in key sectors (transportation, residential).

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Global BC Emissions (2000)

Important to note that emissions patterns and trends across regions, countries and sources vary significantly. Better and more current information and emission inventories needed.

Estimated U.S. Black Carbon Emissions

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• The United States currently accounts for approximately 8% of the global total, and this fraction is declining.

• Long-term trends show a steady decline in emissions since 1920s due to changes in fuel use, more efficient combustion of coal, and implementation of PM controls.

• Mobile sources are the largest U.S. BC emissions category, with the majority (~93%) coming from diesel engines.

U.S. BC Emissions (2005)

• EPA projects mobile sources BC emissions to decline 86% by 2030 due to new engine standards already promulgated. Diesel retrofit programs for in-use mobile sources will complement these standards.

Considering Possible Climate and Health Benefits

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• Location/timing of emissions and co-emitted pollutants are important.

• Reducing emissions from BC-rich sources like mobile diesels most likely to provide climate benefits.

• Reducing emissions that affect the Arctic, Himalayas and other ice/snow-covered regions may be particularly beneficial.

• Health benefits depend on reducing human exposures.

Areas of Focus for Climate and Health Co-Benefits

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•For potentially greatest climate and health co-benefits:– residential cookstoves (globally)– brick kilns and coke ovens (in Asia)– mobile diesels (globally)

Sensitive Regions• Arctic

– transportation sector (land-based diesel engines and Arctic shipping)– residential heating (wood-fired stoves and boilers)– forest, grassland, and agricultural burning

• Himalayas– residential cooking– industrial sources (e.g., coal-fired brick kilns)– transportation, primarily on-road and off-road diesel engines

Research NeedsKey uncertainties: Atmospheric processes affecting BC concentrations (e.g.,

transport and deposition) Aerosol-cloud interactions (e.g., radiative and

precipitation effects) Climate effects of aerosol mixing state Emissions of BC and co-emitted pollutants from specific

regions, sources Warming effect of non-BC aerosols in Arctic Impacts of BC on snow and ice albedo Climate impacts of other types of light-absorbing

carbonaceous particles (e.g., “Brown Carbon”) Shape and magnitude of PM health impact function Differential toxicity of PM components and mixtures Impacts of BC on ecosystems and crops (dimming)

Policy-relevant research needs: Continued investigation of basic microphysical and

atmospheric processes affecting BC and other aerosol species to support the development of improved estimates of radiative impacts, particularly indirect effects.

Improving global, regional, and domestic BC emissions inventories with more laboratory and field data on activity levels, operating conditions, and technological configurations, coupled with better estimation techniques for current and future emissions.

Focused investigations of the climate impacts of brown carbon (BrC).

Research on the impact of aerosols in snow- and ice-covered regions such as the Arctic.

Standardized definitions and improved instrumentation and measurement techniques for light-absorbing PM, coupled with expanded observations.

Continued investigation of the differential toxicity of PM components and mixtures and the shape and magnitude of the PM health impact function.

More detailed analysis and comparison of the costs and benefits of mitigating BC from specific types of sources in specific locations.

Refinement of policy-driven metrics relevant for BC and other short-lived climate forcers.

Analysis of key uncertainties.13

Black Carbon-Related Initiatives and Reports

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•Arctic Council (http://www.arctic-council.org) • Task Force on Short-Lived Climate Forcers• Arctic Monitoring and Assessment Program• Arctic Contaminants Action Program

• Clean Air and Climate Coalition (http://www.unep.org/ccac)

• Global Alliance for Clean Cookstoves (http://cleancookstoves.org)

• UN Environment Programme:Integrated Assessment of Black Carbon and Tropospheric Ozone (http://www.unep.org/dewa/Portals/67/pdf/Black_Carbon.pdf)

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Thank youLesley JantarasamiOffice of Air and RadiationOffice of Atmospheric ProgramsClimate Change Division jantarasami.lesley@epa.gov

www.epa.gov/climatechange www.epa.gov/blackcarbon