Air Quality and Climate Air Quality and Climate ConnectionsConnections

Green and Environmental Systems Regional and Urban Air Quality: Now and in the

FutureNew York Academy of Sciences, NY

February 28, 2007

Arlene M. Fiore(arlene.fiore@noaa.gov)

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)

The U.S. smog problem is spatially widespread,

affecting >100 million people [U.S. EPA, 2004]

Annual Average PM2.5 in 2003

U.S. EPA, 2004

Exceeds standard

AEROSOLS (particulate matter)

U.S. EPA, 2006

OZONE

Nonattainment Areas (2001-2003 data)

4th highest daily max 8-hr O3 > 84 ppbv

Air pollutants affect climate by absorbing or scattering radiation

NMVOCsCO CH4

NOx

pollutant sources

+

O3

+OH

H2O

Black carbon(soot) sulfates

T

T

Aerosols interact with sunlight“direct” + “indirect” effects

composition matters!

Surface of the Earth

Greenhouse gasesabsorb infrared radiation

T

more cloud droplets

Smaller droplet size clouds last longer less precipitation

atmospheric cleanser

Radiative forcing of climate (1750 to present):Important contributions from air pollutants

IPCC, 2007

50% anth. NOx

50% anth. CH4

50% anth.VOC

1995(base)

50% anth.VOC

50% anth.CH4

50% anth.NOx

AIR QUALITY: Number of U.S. summer grid-square days with

O3 > 80 ppbvCLIMATE: Radiative Forcing (W m-2)

Fiore et al., GRL, 2002

Double dividend of Methane Controls: Decreased greenhouse warming and improved air quality

Ozone precursors

NOx OH

CH4

Results from GEOS-Chem global tropospheric chemistry model (4°x5°)

CLE A B C

0.2

0.1

0.0

-0.2

-0.1OZONEMETHANE

+0.16 Net Forcing (W m-2)

+0.080.00 -0.08

Reducing tropospheric ozone via methane controls decreases radiative forcing (2030-2005)

Anthropogenic CH4 Emissions (Tg yr-1)

Control scenarios reduce 2030 emissions relative to CLE by:A) -75 Tg (18%) – cost-effective nowB) -125 Tg (29%) – possible with current technologiesC) -180 Tg (42%) – requires new technologies

West and Fiore, 2005; Fiore et al., in prep

Radiative Forcing of Climate

A

B

C

CLE Baseline

How might future changes in aerosols affect climate?

HISTORICAL and FUTURE SCENARIOS

CO2 concentrations

pp

mv

Emissions of Short-lived Gases and Aerosols (A1B)

1880 1920 1960 2000 2040 2080

NOx (Tg N yr-1)

SO2 (Tg SO2 yr-1)

BC (Tg C yr-1)25201510 5 0

250

200

150

100

50

605040302010

Horowitz, JGR, 2006

Large uncertainty in future emissiontrajectories for short-lived species

Pollution controls

A1B

IPCC, 2001

Up to 40% of U.S. warming in summer (2090s-2000s) from short-lived species

From changing well-mixed greenhouse gases +short-lived species

From changing only short-lived species

Warming from increases in BC + decreases in sulfate;depends critically on highly uncertain future emission trajectories

Results from GFDL Climate Model [Levy et al., 2006]

Change in Summer Temperature 2090s-2000s (°C)

Changes in global anthropogenic emissions affect regional air quality

2030 A1

1995 Base caseIPCC 2030Scenario

Anthrop. NOx

emis.Global

U.S.

Methane emis.

A1 +80% -20% +30%

GEOS-Chem Model (4°x5°) [Fiore et al., GRL, 2002]

Rising global emissions may offset U.S. efforts to reduce pollution

longer O3 season

How will changes in climate influence regional air quality?

Probability of daily max 8-h O3 > 84 ppbv vs. daily max. temperature

Observed surface ozone over the U.S. Observed surface ozone over the U.S. correlates strongly with temperaturecorrelates strongly with temperature

Lin et al., 2001

1980-1998 summertimeobservations

Pro

bab

ilit

y

0.5

0.4

0.3

0.2

0.1

0.0 62 71 80 89 98 (°F)

Temperature

New England

Southeast

Los Angeles

How does climate affect air quality?

pollutant sources

strong mixing

(1) Meteorology (stagnation vs. well-ventilated boundary layer)

Degree of mixing

Boundary layer depth

(2) Emissions (biogenic depend strongly on temperature; fires)

T

VOCs

T

(3) Chemistry responds to changes in temperature, humidity

NMVOCsCO, CH4

NOx+ O3+ OHH2O

generally faster reaction rates

Increase with T, drought?

Ozone

CO

Ventilation (low-pressure system)

HEATWAVE

GRGCarlos Ordóñez ordc@aero.obs-mip.fr Laboratoire d'Aérologie Toulouse, France

CO and O3 from airborne observations (MOZAIC)

Above Frankfurt (850 hPa; ~160 vertical profiles

Contribution to GEMS, Integrated Project of the 6th EC Framework ProgrammeGEMS-GRG subproject coordinated by Martin Schultz (m.schultz@fz-juelich.de)

Pollution build-up during 2003 European heatwave

Stagnant high pressure system over Europe

(500 hPa geopotential anomaly relative to 1979-1995 for 2-14 August, NCEP)

H

Observations during 2003 European heatwave show enhanced biogenic VOC concentrations

Hogrefe et al., EM, 2005

Measurements from August 2003 Tropospheric Organic Chemistry Experiment (TORCH) in Essex, UK, during hottest conditions ever observed in the UKc/o Dr. Alistair Lewis, University of York, UK

con

cen

trat

ion

(p

ptv

) temperature (°C)

BVOCs

= 95 °F

= 86 °F

= 77 °F

Impacts on surface O3 from T-driven increases in reaction rates, humidity, and BVOC emissions

due to changes in climate

Climate-driven O3 increases may counteract air quality improvements achieved via local anthropogenic emission reductions

3 p.m. O3 change (ppbv) in 3-day O3 episode with CMAQ model (4x4 km2), applying T change from 2xCO2

climate (changes in meteorology not considered) [Steiner et al., JGR, 2006]

pp

bv

ppbv

normalized to a +1°C5

4

3

2

1

0reaction humidity BVOC combinedrates

O3 response depends on local chemistry (available NOx)

Changing climate may increase pollution events over the eastern U.S.

Daily max 8-hr O3

(5-year summer mean)

ppbv

Tracer of anthropogenic pollution (July-August)

Simulations using present-day emissions with future climates

Regional CMAQ model (36 km2)with GISS boundary conditionsHogrefe et al., JGR 2004; EM 2005

in GISS global model (4°x5°)[Mickley et al., GRL, 2004]

Rel

ativ

e F

req

uen

cy (

%) 2045-2052 A1B

1995-2002

Increase in frequency and duration of pollution eventsdue to decrease in frequency of mid-latitude storms

Eastern U.S.

Surface O3 change under future climate varies: increases in polluted regions; decreases in

“background”Mean annual change in number of days where daily max 8-hr O3 > 80 ppbv

(2090-2100 A1) – (1990-2000)

MOZART-2 global tropospheric chemistry model with meteorology from NCAR climate model [Murazaki and Hess, J. Geophys. Res., 2006]

More inflow of clean air from Gulf of Mexico

Less trans-Pacific transport

Increase in polluted (high-NOx) regions

Air Quality and Climate Connections: Research Focal Points

Costs and benefits of “win-win” (e.g. BC, CH4) 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)