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Explore viable methane control options for air quality & climate benefits, cost savings, and global impact. Learn about reducing methane emissions and its effects on ozone levels and radiative forcing.
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Geophysical Fluid Dynamics Laboratory Review June 30 - July 2, 2009
Climate and Air Quality Presented by Arlene Fiore
Addressing air quality and climate via methane emission controls: A viable option? Cost-saving Cost-effective All identified (industrialized nations) METHANE CONTROL OPTIONS 10% of anth. emissions 20% of anth. emissions 0 20 40 60 80 100 120 Methane emission reduction potential (Mton CH4 yr-1) IEA [2003] for 5 industrial sectors ~25% of global anthropogenic emissions at cost-savings / low-cost (West and Fiore, 2005)
Decreasing methane lowers global surface O3 background Range across 18 models Robust result across models N. Amer. Europe E. Asia S. Asia -20% Domestic Anthrop. Emissions -20% Foreign Anthrop. Emissions N. Amer. Europe E. Asia S. Asia N. Amer. Europe E. Asia S. Asia • Intercontinental emission controls: CH4 ≈ NOx+NMVOC+CO Domestic emission controls: NOx+NMVOC+CO more effective (Results from TF HTAP model intercomparison; Fiore et al., 2009)
Benefits from CH4 controls to climate and air quality:Decreased radiative forcing and high-O3 events Methane emission reductions are applied to BASE emission scenario (2005 to 2030 full-chemistry transient simulations in MOZART-2) CLIMATE AIR QUALITY Net Forcing Percentage of model grid-cell days where surface ozone (MDA8) > 70 ppbv BASE 2005 BASE 2030 CH4 CONTROL CH4=700 ppb (W m-2) OZONE METHANE Cost-effective controls prevent increase in O3 > 70 ppbv in 2030 relative to 2005 in Europe BASE CH4=700 ppb CH4 CONTROL (Fiore et al., 2008)
Contributions to change in methane lifetime from 1991-1995 to 2000-2004 in BASE + = Decrease in methane lifetime (years) DT(+0.3K) BASE DOH(+1.2%) Climate sensitivity: Small increases in temp. and OH shorten the methane lifetime Global mean surface methane (ppb) OBSERVED BASE (constant emis.) ANTH (time-varying) ANTH+BIO (time-varying) (Fiore et al.,2006)
Summary: Connecting climate and air quality via O3 & CH4 CLIMATE AND AIR QUALITY BENEFITS FROM CH4 CONTROL • Decreased hemispheric background O3 (robust across models) • Complementary to NOx, NMVOC controls • Independent of reduction location (but depends on NOx) IMPACT OF CHANGING CLIMATE ON METHANE TRENDS ? • 1990 to 2004 model trend driven by increasing T, OH • Trends in global lightning activity? • Other potential climate feedbacks (on sources and sinks) (Fiore et al., 2002, 2006; West and Fiore, 2005; Fiore et al., 2008, 2009)
NEW DIRECTION: Impact of Future Changes in Climate on Air Quality 20-year AM3 simulations with annually-invariant emissions of ozone and aerosol precursors (except for lightning NOx), to isolate role of climate change • Present Day Simulation (“1990s”): observed SSTs and sea ice (1981-2000 mean) • Future Simulation (“A1B 2090s”): observed SSTs and sea ice + average 2081-2100 changes from 19 IPCC AR-4 models CHANGES IN SUMMER (JJA) MEAN DAILY MAX 8-HOUR OZONE
Geophysical Fluid Dynamics LaboratoryReview June 30 - July 2, 2009