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CCAC Science Advisory Panel Annual SLCP Science Update. CCAC High Level Assembly Oslo, Norway 2-3 September, 2013 Presented by Dr. Drew T. Shindell , Chair of CCAC Science Advisory Panel. Black Carbon, Methane, Troposheric Ozone, Hydrofluorocarbons ( HFCs )
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CCAC Science Advisory PanelAnnual SLCP Science Update CCAC High Level Assembly Oslo, Norway 2-3 September, 2013 Presented by Dr. Drew T. Shindell, Chair of CCAC Science Advisory Panel
Black Carbon, Methane, Troposheric Ozone, Hydrofluorocarbons (HFCs) Concentrations decrease in weeks to years; climate impacts in 1-2 decades CO2 and other long-lived greenhouse gases A significant portion remains in the atmosphere for millennia Climate benefits accrue over multiple decades
The role of HFCs in mitigating 21st century climate change • Controls on methane and BC-rich sources can prevent 0.5°C warming by 2050 • Replacing High-GWP HFCs with low-GWP alternatives can prevent an additional 0.1°C of warming by 2050.
SLCPs Can Reduce Projected Sea-Level Rise SLCP mitigation can reduce the rate of SLR by 18% in 2050 and 24% in 2100 ~50% reduction when combined with immediate CO2 mitigation
Air Pollution & The Burden of Disease • Household air pollution • 3.5 million deaths and 100 million disability-adjusted life years • Ambient air pollution • 3.2 million deaths • Tropospheric Ozone • ~152,000 deaths
Cost and Health benefits of improved access to modern energy [Pachauri et al., ERL, 2013]
BC Impacts of Specific Emission Sources • Gas flaring, particularly in the Arctic, substantial source of BC in the region • Diesel generators important source of BC in counties with limited public power supply • Studies support reducing emissions from some BC-rich sources (e.g. diesel engines) provide clear climate benefit
BC Emissions from Kerosene-Wick Lamps • BC emissions from kerosene 20-fold increase over previous estimates • Total forcing estimated at 7% of BC forcing by all other energy-related sources • Kerosene-Wick Lamps used in millions of households in developing countries • Affordable clean and available options exist
Methane Leakage Rates Higher than Previously Estimated • Fugitive emissions from gas extraction, transmission and distribution greater than expected in many cases • New Utah data: 6-12% of production leaked! • Emissions implications for growing global use of natural gas Transcontinental CH4 showing high values near the Gulf of Mexico [Leifer et al., AE, 2013]
Climate benefits more certain in snow/ice covered regions • Benefits appear to be both very large and certain for the Himalayas and Arctic • Benefits can be very large in other regions (e.g. China), but lower confidence • Similar distinction between various measures