CCAC Science Advisory PanelAnnual SLCP Science Update

CCAC High Level AssemblyOslo, Norway

2-3 September, 2013Presented 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 gasesA significant portion remains in the atmosphere for millenniaClimate 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

Transcontinental CH4 showing high values near the Gulf of Mexico [Leifer et al., AE, 2013]

• 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

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

Climate benefits by measure

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