Identifying Chemistry-Climate-Air Quality Connections To Inform Public Policy

AAAS Meeting, VancouverFebruary 19, 2012

Arlene M. Fiore

Acknowledgments. Jasmin John, Meiyun Lin, Vaishali Naik, Larry Horowitz, D.J. Rasmussen, Alex Turner, GAMDT (GFDL); Oliver Wild (U Lancaster): Mike Bauer (CU/GISS)

0 20 40 60 80 100 120Methane reduction potential (Mton CH4 yr-1)

North AmericaRest of Annex IRest of World

Ozone reduction (ppb)

Cost-saving reductions

<$10 / ton CO2 eq.

All identifiedreductions

Addressing air quality and climate via methane emission controls: A viable option?

~25% of global anthrop. emissions at cost-savings / low-cost

>1 ppb decrease in global surface ozone West & Fiore, ES&T, 2005; Fiore et al., GRL, 2002

IEA [2003] for 5 industrial sectors

0.7

1.4

1.9

10% of anth. emissions

20% of anth. emissions

0 20 40 60 80 100 120 Methane reduction potential (Mton CH4 yr-1)

(industrialized nations)

Benefits of ~25% decrease in global anthrop. CH4 emissions

~ 1 ppb, robust across models (factor of 2 range)[Fiore et al., JGR, 2009; TF HTAP, 2007, 2010; Wild et al., ACPD, 2012]7700-400,000 annual avoided cardiopulmonary premature mortalities in the N. Hemisphereuncertainty in concentration-response relationship only [Casper Anenberg et al., ES&T, 2009]

Range over 18 models

Global meanavoided warming in

2050 (°C)[WMO/UNEP, 2011]

CLIMATEOZONE AIR QUALITY

Atmospheric CH4 and surface O3 over the next century?

Tool: GFDL CM3 chemistry-climate model

Donner et al., J. Climate, 2011; Golaz et al., J. Climate, 2011;Naik et al., in prep, Horowitz et al., in prep

• ~2°x2°; 48 levels• Atm-ocean-sea ice-land GCM• Fully coupled chemistry in troposphere+stratosphere• Aerosol – warm cloud interactions

Tg N

yr-1

Representative Concentration Pathways (RCPs)

c/o V. Naik

METHANE

NOx Emissions

ppb

c/o J. John

RCP8.5RCP6.0 RCP4.5RCP2.6

RCP4.5* WMGG

RCP4.5

RCP8.5

Multiple feedbacks complicate projections of atmospheric CH4 and O3 abundances

O3 + hν

Troposphere

O1D + H2O OH CH3+H2O k+ CH4

T T

Stratospheric O3

NOx, CO, NMVOC, CH4

Anthropogenic sources Biospheric sources

tropopause

surface

CH

CHOHTk

B

]][)[( 4

4

tCH4

=

NOx

Negative feedback of warming climate on methane lifetime; anthrop. emission trajectory can amplify or counteract

RCP4.5* WMGG only:

tCH4: -5%Rising T(+1.4K), OH (LNOx, H2O)

RCP4.5: tCH4: -13%More warming (+2.3K; aerosol), CO, CH4 decrease

RCP 8.5: tCH4: +4%: Doubling CH4 offsets influence of warmer T (+4.5K)

TROPOSPHERIC CH4 LIFETIME IN GFDL CM3 CHEMISTRY-CLIMATE MODEL

Year

s

Percentage changes are (2081-2100) – (2006-2025)J. John et al., in prep

How will O3 air quality evolve over North America? RCP emissions: lower? Warmer climate: higher?

NO CLIMATE CHANGEO3 change estimated from sensitivities derived from TF HTAP model ensemble

Ann

ual m

ean

N. A

mer

. Su

rface

O3 ch

ange

s (pp

b)

Dramatic rise in CH4 in RCP8.5 opposes NOx-driven decreases

July mean obs from U.S. EPA CASTNet site Penn State, PA 41N, 78W, 378m

TEM

P (C

; 10a

m-5

pm a

vg)

MD

A8

O3 (

ppb)Observed O3-T

correlation implies that changes in climate will influence air quality

[Wild et al., revised for ACP]

Over NE USA, stagnation episodes are a major driver of observed surface O3-T correlation: Future evolution?

Number of storms in region each summer (JJA) in RCP8.5, GFDL CM3 model

Cylones diagnosed from 6-hourly SLP with MCMS software from Mike Bauer, (Columbia U/GISS)

Robust across models? [e.g., Lang and Waugh, 2011] Can we evaluate modeled

relationships btw air quality and climate?

Leibensperger et al. [2008]: strong anticorrelation in summer between (a) number of migratory cyclones over Southern Canada/NE U.S. and (b) number of stagnation events and associated NE US high-O3 events

A. Turner et al., in prep

July Monthly avg. daily max T

How well does a global chemistry-climate model simulate regional O3-temperature relationships?

Rasmussen et al., Atmos. Environ., 2012

Model captures observed O3-T relationship in NE USA in July, despite high O3 bias

MonthS

lope

s (p

pb O

3 K

-1)

CASTNet sites,NORTHEAST

USA

“Climatological” O3-T relationships:Monthly means of daily max T and monthly means of MDA8 O3

AM3: 1981-2000OBS: 1988-2009

July

Mon

thly

avg

. MD

A8

O3

r2=0.41, m=3.9

r2=0.28, m=3.7

Broadly represents seasonal cycle

What is the combined impact of climate + emission on surface O3 over North America?

EMISSIONS CHANGE ONLY

Ann

ual m

ean

N. A

mer

ican

surfa

ce O

3 ch

ange

(ppb

)

Why does O3 increase in GFDL CM3 RCP8.5? Higher CH4 sensitivity? Increased strat O3 influence? [e.g., Butchart et al., 2006; Hegglin & Shepherd, 2009; Kawase et al., 2011; Li et al., 2008; Shindell et al. 2006; Zeng et al., 2010]

How well do models represent strat-to-trop O3 transport?

5

0

-5

-10

GFDL CM3 RCP8.5 RCP4.5 ens. meanIndividual members

EMISSIONS + CLIMATE CHANGE

[Wild et al., revised for ACP]

Western NA: Particularly active region for STE in present day,a good test case for model evaluation

Satellite observations

Decreasing humidity

GOES-West water vapor

AIRS total column ozoneAM3 “nudged high-res” (~50km2 )

simulations

250 hPa jet (color) 350 hPa geopotential height (contour)

250 hPa potential vorticity

DU

AM3 resolves features consistently with satellite perspectiveM. Lin et al., in prep.

Upper level dynamics associated with a deep stratospheric ozone intrusion (21:00UTC May 27, 2010)

Identifying chemistry-climate-air quality connections to inform public policy… some final thoughts

• Methane controls as “win-win” for climate and O3 air quality

• Analysis of long-term chemical and meteorological obs may reveal key connections between climate and air pollution Crucial for testing models used to project future changes Need to maintain long-term observational networks

• Climate-driven influences on air quality Need better process understanding at regional scale;

new opportunities with chemistry-climate models Potential for shifts in relative importance of locally produced vs.

transported O3

Cooling influence on climate (by lowering both methane and O3) Decrease baseline surface O3 (robust across models) Complex chemistry-climate feedbacks along future trajectories