Air Quality and Climate Connections

Transcription

1 Air Quality and Climate Connections Arlene M. Fiore Acknowledgments: Larry Horowitz, Chip Levy, Dan Schwarzkopf (GFDL) Vaishali Naik, Jason West (Princeton U), Allison Steiner (U Michigan) Carlos Ordóñez (Laboratoire d'aérologie), Martin Schulz (Jülich) Green and Environmental Systems Regional and Urban Air Quality: Now and in the Future New York Academy of Sciences, NY February 28, 2007

2 The U.S. smog problem is spatially widespread, affecting >100 million people [U.S. EPA, 2004] OZONE AEROSOLS (particulate matter) Nonattainment Areas ( data) Annual Average PM 2.5 in th highest daily max 8-hr O 3 > 84 ppbv U.S. EPA, 2006 Exceeds standard U.S. EPA, 2004

3 Air pollutants affect climate by absorbing or scattering radiation Greenhouse gases absorb infrared radiation Aerosols interact with sunlight direct + indirect effects composition matters! T O 3 NMVOCs + CO CH 4 H 2 O OH + NO x atmospheric cleanser T Black carbon (soot) Smaller droplet size clouds last longer less precipitation more cloud droplets sulfates T pollutant sources Surface of the Earth

4 Radiative forcing of climate (1750 to present): Important contributions from air pollutants IPCC, 2007

5 Double dividend of Methane Controls: Decreased greenhouse warming and improved air quality Results from GEOS-Chem global tropospheric chemistry model (4 x5 ) CLIMATE: Radiative Forcing (W m -2 ) NO x OH AIR QUALITY: Number of U.S. summer grid-square days with O 3 > 80 ppbv CH 4 50% anth. VOC 50% anth. CH 4 Ozone precursors 50% anth. NO x 1995 (base) 50% anth. VOC 50% anth. CH 4 50% anth. NO x Fiore et al., GRL, 2002

6 Reducing tropospheric ozone via methane controls decreases radiative forcing ( ) Anthropogenic CH 4 Emissions (Tg yr -1 ) CLE Baseline A B Radiative Forcing of Climate Net Forcing (W m -2 ) C OZONE METHANE CLE A B C Control scenarios reduce 2030 emissions relative to CLE by: A) -75 Tg (18%) cost-effective now B) -125 Tg (29%) possible with current technologies C) -180 Tg (42%) requires new technologies West and Fiore, 2005; Fiore et al., in prep

7 How might future changes in aerosols affect climate? ppmv HISTORICAL and FUTURE SCENARIOS CO 2 concentrations IPCC, 2001 A1B Emissions of Short-lived Gases and Aerosols (A1B) NO x Emissions (Tg N/yr) NO x (Tg N yr -1 ) SO 2 Emissions (Tg SO 2/yr) SO 2 (Tg SO 2 yr -1 ) Pollution controls Large uncertainty in future emission trajectories for short-lived species BC Emissions (Tg C/yr) 1860 BC (Tg C yr -1 ) Horowitz, JGR,

8 Up to 40% of U.S. warming in summer (2090s-2000s) from short-lived species Results from GFDL Climate Model [Levy et al., 2006] From changing well-mixed greenhouse gases +short-lived species From changing only short-lived species Change in Summer Temperature 2090s-2000s ( C) Warming from increases in BC + decreases in sulfate; depends critically on highly uncertain future emission trajectories

9 Changes in global anthropogenic emissions affect regional air quality 1995 Base case 2030 A1 IPCC 2030 Scenario Anthrop. NO x emis. Global U.S. Methane emis. A1 +80% -20% +30% longer O 3 season GEOS-Chem Model (4 x5 ) [Fiore et al., GRL, 2002] Rising global emissions may offset U.S. efforts to reduce pollution How will changes in climate influence regional air quality?

10 Observed surface ozone over the U.S. correlates strongly with temperature Probability of daily max 8-h O 3 > 84 ppbv vs. daily max. temperature summertime observations New England Probability Los Angeles 0.1 Southeast ( F) Temperature Lin et al., 2001

11 How does climate affect air quality? (1) Meteorology (stagnation vs. well-ventilated boundary layer) Degree of mixing pollutant sources strong mixing Boundary layer depth (2) Emissions (biogenic depend strongly on temperature; fires) T VOCs Increase with T, drought? (3) Chemistry responds to changes in temperature, humidity T generally faster reaction rates NMVOCs + NO x + OH O 3 CO, CH 4 H 2 O

12 Pollution build-up during 2003 European heatwave CO and O 3 from airborne observations (MOZAIC) Above Frankfurt (850 hpa; ~160 vertical profiles Ozone CO HEATWAVE Stagnant high pressure system over Europe (500 hpa geopotential anomaly relative to for 2-14 August, NCEP) H Ventilation (low-pressure system) Carlos Ordóñez ordc@aero.obs-mip.fr Laboratoire d'aérologie Toulouse, France Contribution to GEMS, Integrated Project of the 6th EC Framework Programme GEMS-GRG subproject coordinated by Martin Schultz (m.schultz@fz-juelich.de) GRG

13 Observations during 2003 European heatwave show enhanced biogenic VOC concentrations concentration (pptv) BVOCs temperature ( C) = 95 F = 86 F = 77 F Measurements from August 2003 Tropospheric Organic Chemistry Experiment (TORCH) in Essex, UK, during hottest conditions ever observed in the UK c/o Dr. Alistair Lewis, University of York, UK Hogrefe et al., EM, 2005

14 Impacts on surface O 3 from T-driven increases in reaction rates, humidity, and BVOC emissions 3 p.m. O 3 change (ppbv) in 3-day O 3 episode with CMAQ model (4x4 km 2 ), applying T change from 2xCO 2 climate (changes in meteorology not considered) [Steiner et al., JGR, 2006] due to changes in climate normalized to a +1 C 5 4 ppbv O 3 response depends on local chemistry (available NO x ) ppbv 0 reaction humidity BVOC combined rates Climate-driven O 3 increases may counteract air quality improvements achieved via local anthropogenic emission reductions

15 Changing climate may increase pollution events over the eastern U.S. Simulations using present-day emissions with future climates Daily max 8-hr O 3 (5-year summer mean) Tracer of anthropogenic pollution (July-August) Relative Frequency (%) Eastern U.S A1B ppbv Regional CMAQ model (36 km 2 ) with GISS boundary conditions Hogrefe et al., JGR 2004; EM 2005 in GISS global model (4 x5 ) [Mickley et al., GRL, 2004] Increase in frequency and duration of pollution events due to decrease in frequency of mid-latitude storms

16 Surface O 3 change under future climate varies: increases in polluted regions; decreases in background Mean annual change in number of days where daily max 8-hr O 3 > 80 ppbv ( A1) ( ) Less trans-pacific transport Increase in polluted (high-no x ) regions More inflow of clean air from Gulf of Mexico MOZART-2 global tropospheric chemistry model with meteorology from NCAR climate model [Murazaki and Hess, J. Geophys. Res., 2006]

17 Air Quality and Climate Connections: Research Focal Points Costs and benefits of win-win (e.g. BC, CH 4 ) and win-lose (e.g. sulfate) strategies for joint mitigation of air pollution and climate forcing Aerosol feedbacks on climate, globally and regionally Response of biogenic emissions and fires to changes in climate and land-use Evolution of air quality with global change (climate + anthropogenic and natural emissions)