introduction to the role of tropospheric ozone and arctic climate

8/9/2019 Introduction to the Role of Tropospheric Ozone and Arctic Climate

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Introduction to the Role ofTropospheric Ozone and Arctic

Climate

Ellen Baum

May 8, 2008


2/20

2

There is a significant global role for

tropospheric ozone and climateTemperature impact from CO2 compared to other climate

forcings, relative to 1750

0

0.2

0.4

0.6

0.8

1

1.2

1.4

CO2 Short-lived Climate Forcings

Tem

peratureind

egreesC

Blackcarbon

Troposphericozone

Methane

Carbon

dioxide

Ramana

than,

2008


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3

Initial Arctic modeling suggests a seasonally, averagedtropospheric ozone-derive temperature increase of 0.28o C

Temperature impact from CO2 compared to other climate forcings,

relative to 1880

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

CO2 Short-lived Climate Forcings

T

emperatureind

egreesC

Blackcarbon

Troposphericozone

Methane

Carbon

dioxide

Calculatedfrom

Quinn,

et.al.,

ACP,

200

8

Note: Different models were used to derive Global(previous slide) and Arctic (this slide) values.


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Tropospheric ozone is formed in the

atmosphere, not emitted Tropospheric ozone is formed in the atmosphere

from precursor pollutants - oxides of nitrogen,volatile organic compounds, carbon monoxide,and methane in the presence of light and thusnot directly emitted like most other air pollutants.

Atmospheric lifetime of ozone is 1 to 2 weeks insummer and 1 to 2 months in winter.

Ozone produced in a polluted region of onecontinent can be transported to anothercontinent.


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How ozone heats the Arctic

The dominant heating pathway is probably transfer of heatproduced by Northern Hemisphere ozone into the Arctic.

Followed by transport of ozone from outside the Arctic To a smaller extent, ozone formation within the Arctic

At the same time, there remain research questions to teaseout the relative contributions and better understandprecursor roles, including

Contribution formed in the Arctic, both from in-Arctic

precursors and precursors transported into the Arctic. Howwill this change with a warmer Arctic?

Importance of lifetimes, locations and seasonality of theshorter-lived precursors

Relevance of looking at specific VOCs


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1950sPresent1980s

NMVOCs + NOx +CH4, CO

Ozone abatement strategies have evolvedalong with understanding of the O

3

issues

Abatement Strategy:

O3 smog recognizedas an URBAN problem:

Los Angeles,Haagen-Smit identifieschemical mechanism

Smog consideredREGIONAL problem;role of biogenicVOCs discovered A GLOBAL perspective:

Cimate impacts and

role of intercontinentaltransport, background

adapted from Fiore, 2002


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Different strategies and need for air

quality versus climate benefits Air quality programs to

reduce ozone levels

focus largely onreducing peak ozonelevels to protect humanhealth and cropproduction.

This favors strategiesreducing localprecursors - NOX and

non-methane VOCs that are majorcontributors to peakozone levels.


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Need lower background for

climate benefits To benefit climate by reducing net warming, a balanced approach must

be taken to reducing all major ozone precursors given their complexatmospheric interactions.

NOxis the most complicated precursor. In the shortrun, it reduces ozone and the radiative forcing fromozone. Over a longer period, however, reductionsincrease the lifetime of methane, and thereforecontribute to warming. Also the nitrate aerosol hasa cooling effect, which reductions remove.

Its unclear where the balance lies between thenegative impacts from increased in methane lifetimeand aerosols, particularly nitrate, and the positive

climate benefits from ozone reductions. Thissuggests that NOx reductions continue to bepursued for air quality benefits, with the recognitionthat climate benefits will need to come largely fromcarbon monoxide and methanereductions

NOx OH

CH4 lifetime


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Climate role of CO, NOx and NMVOC

Shindell, Oslo Workshop, from

IPCC 4AR, 2007

Because COalso uses OH

as anatmospheric

sink, reducingit will makemore OH

available as

methane sink.

from pre-industrial time

Using same calculations, andwithout double counting,

methane is 0.59 W/m2, plusanother 0.20 W/m2 frommethane emissions viaozone.


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Methane is different

Unlike other ozone precursors, methane is not a typical, short-livedozone precursor.

Because methane has a long atmospheric lifetime (8-10 years),emissions become well mixed.

Neither air quality nor climate benefits depend strongly on thelocation of the CH4 emission reductions, implying that the lowestcost emission controls can be targeted.

There are, though, regions where methane effects on O3 areenhanced. These include locations with high NOx emissions (e.g., insouthern California); regions near the down welling branches of theHadley cell, at roughly 30N and 30S (over the Sahara region ofNorth Africa, the Middle East), or regions with active convection

(Caribbean Sea and Gulf Coast of the United States).

Given that most of the ozone-related temperature in the Arcticcomes from global transport, the benefits of these reductionsshould be felt in the Arctic.

MODELED CLIMATE IMPACTS OF 50%


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MODELED CLIMATE IMPACTS OF 50%REDUCTIONS IN ANTHROPOGENIC

EMISSIONSCH4 NOx* VOC NOx

&VOC

CO

MethaneRadiative

Forcing (W/m2)

-0.3 +.06 -.01 +.05 -.02

OzoneRadiative

Forcing (W/m2)

-.07 -.06 -.01 -.07 -.01

Total Forcing

(W/m2)

-.37 0 -.02 -.02 -.03

EPA/OAQPS

Workshop, 2001

* doesnt include aerosolclimate effects


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Near-term climate impacts are critical to Arcticprotection

Given concerns about irreversible arctic climateimpacts that may occur within the next two

decades, should a 20 year GWP, instead of thetypical 100 year equivalency, be used to evaluatearctic impact reduction options?

Using 20 year impacts more than doubles thewarming benefits from methane emissionsreductions and would increase CO reductionwarming benefits by at least 50 percent.

This will also increase the economic value ofsuch emissions, which means much moreexpensive reductions than typically addressed incurrent supply curves are feasible.

Rypdal, 2005


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Where are emissions occurring?

Next four slides.


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CO, emissions, Edgar 2000

refineries, coke ovens, gas

works

Power generation

Industry

Oil production,

Charcoal production

Power generationIndustry

Residential

Transport road

Residential, Commercial

onroad transport

non-road land transport, ie.

rail

Air transport

ShippingIron and Steel

Deforestation

Savanna burning

Agriculture waste burning

Temperate fires

Waste incineration

m an g a u e

grassland f ires

Biofuels

FossilFuels

Agriculture/biomassburning


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NOX, 2000 FROM EDGAR

TROPICAL FOREST FIRES

BUILDING MATERIALS

NON-FERROUS

IRON AND STEEL

OIL PRODUCTIONSHIPPING

AVIATION

NON ROAD TRANSPORT

ROAD TRANSPORTRESIDENTIAL, COMMERICAL

REFINERIES, COKE OVENS,

GAS WORKS

POWER GENERATION

INDUSTRIAL

INDUSTRY

POWER GENERATION

RESIDENTIAL

SAVANNAH AND SHRUBS

FIRES

AG. WASTE BURNING

MID AND HIGH LAT FOREST

FIRES

MID AND HIGH LAT GRASS

FIRES

Biofuels

Fossil Fuels

Indu

-stry

Agriculture/biomassburning


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Non methane VOCS, 2000

REFINERIES,

GAS WORKS,COKE OVENS

INDUSTRYRESIDENTIAL

INDUSTRYPOWER

GENERATION

RESIDENTIALROAD

TRANSPORT

NON-ROADTRANSPORT

AIR

OIL

PROD

GAS

PRODUCTION/

TRANS

IRON &STEEL

SOLVENTS

TROPICAL

FOREST FIRES

SAVANNAH

FIRES

AG WASTE

BURNING

MID LAT

FOREST FIRES

MID LAT

SAVANNAH

FIRES

WASTE

HANDLING

Biofuels

Fossil

Fuels

Industry

Agriculture/biomass

burning


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METHANE, 2000 EDGAR

HUMAN

WASTEWATERDISPOSAL

WASTEWATER

TREATMENT

LANDFILLS

15

MID/HIGHLATITUDE

FOREST FIRESTAG WASTE

BURNING

SAVANNAH AND

SHRUB FIRES

TROPICAL

FOREST FIRES

ANIIMAL WASTE

MANAGEMENT

ENTERIC

FERMENTATION RICE

CULTIVATION

GAS

PRODUCTION

GAS FLARING

OIL PRCESSES

OIL PRODUCTION

COAL

PRODUCTION

COMMERCIAL/

RESIDENTIAL

BIOFUEL

RESIDENTIAL


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Conclusions

Traditional clean air regulation programs

addressing ozone will not benefit climate andthus the Arctic.

Substantial methane and CO reductions areneeded reduce ozone warming of the Arctic.

Research and analytical questions remain,

including whether targeting global hot spots toreduce ozone could have an enhanced benefit inthe Arctic.


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Climate impact, by source category, from

multiple emissions, in 2030, SRES A1B

From Unger, et. al. JGR, 2008

03 ST =ozoneimpact

03 LT = CH4

affects

Black numbera top eachcolumn is totalforcing


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Relative importance of different regions to annual mean

Arctic concentration at surface and atmosphere.

From Shindell, et. al. ACPD, 2008

introduction to the role of tropospheric ozone and arctic climate

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