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Air Pollution and the Climate System:Sustainability Now and Later

Tami C. BondDepartment of Civil & Environmental Engineering

University of Illinois at Urbana-Champaign

Photo: NASA

ISTC Seminar SeriesOctober 13, 2009

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Take-home messages

Many pollutants affect climate… it’s more than just the “greenhouse effect”

A broad portfolio of solutions is available… “when” and “where” are considerations

Small sources matter, especially when emissions depend on process

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Outline

1. Human effects on earth’s radiation balance Greenhouse gases; bright & dark particles

2. A special case: carbon particlesThe role of small sources

3. Balancing near-term and long-term goals“Sustainability now and later”

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1. Overview

Human effects on earth’s radiation balanceGreenhouse gases; bright & dark particles

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Our fire dilemma: we like it, and we don’t like it

Benefits: Warmth Sterilization/preservation Process heat Power Mobility Camaraderie Mysticism

Hazards: Poor air quality Health damages Global change

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Both complete & incomplete combustion affect the environment

Particulate Matter (PM)

Othergases *

Carbondioxide (CO2)

Indoorair pollution

Outdoorair pollution(smog, ozone, poor visibility)

Climatechange

* Products of incomplete combustion (PICs):Carbon monoxide (CO),Methane (CH4), Volatile organic compounds (VOCs)

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Many pollutants result in global change

Radiative forcing (W/m2)

warmingcooling

Source:IPCC,2007

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Photo: V. Ramanathan

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Photo: NASA (via Robert Charlson)

Aerosol emissions changing the Earth’s reflectivity

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I’ll contrast three different combustion products.

``

3. combustion-climate links

Other products affect climate also: N2O, ozone, non-soot carbon particles…

O=C=O

Carbon dioxide Sulfate aerosol Soot aerosol

image:Cardiff Univ.

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These combustion products have different sources & lifetimes.

Carbondioxide

3. combustion-climate links

Sulfateaerosol

Sootaerosol

Emissioncause

Fuel quantity,carboncontent

Sulfurin fuels

Poorcombustion

Emissionrate(metric tonne/year)

6.4billion(2000)

70million

(1995, as S)

8million(2000)

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The three combustion products have different atmospheric lifetimes & effects.

3. combustion-climate links

Carbondioxide

Sulfateaerosol

Sootaerosol

Lifetime ~100 yrs ~ 4 days ~ 5-7 days

Effect of1 kg onenergy balance

~1 watt/g

~-200 watt/g

~1800 watt/g

Confidence High Medium Low

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Changing each has different implications.

3. combustion-climate links

Possiblesolutions

Energy withless carbon

Fuel withless sulfur;end-of-pipe

controls

Improvecombustion;end-of-pipe

controls

Carbondioxide

Sulfateaerosol

Sootaerosol

Effect ofchange

Increase:Warming (etc.)

Decrease:Cooling (etc.)

Decrease:Warming (etc.)

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Implication (1) Radiative forcing (W/m2)

warmingcooling

Source:IPCC,2007

Some of the expected warming due to greenhouse gases has been masked by reflective particles.

(Ocean adjustment is another reason for unrealized warming)

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Implication (2)

Removing reflective aerosols will increase warming.

This is happening because of air quality policies.

There is some concern that the climate system will proceed past “tipping points.”

Source: Ramanathan and Feng, PNAS (105), 14245

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GHGs are a poor measure of climate impactwhen products of incomplete combustion are high

100-

year

GW

P10

0-ye

ar G

WP

Bond, Venkataraman and Masera, ESD, 2004Thought process initiated by Smith et al, AREE, 2000

For residential biofuel, climate forcing by products of incomplete combustion is greater than that of greenhouse gases

Many pollutants affect climate… it’s more than just the “greenhouse effect”

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2. Carbon particles, a special case…

…and the role of small sources

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Black carbon – a warming particle

Scattering particle

Light is reflected

away from Earth.

Absorbingparticle

Light is absorbed and turned into heat.

Most particles cool the climate system

Black carbon warms it, so…

Black carbon ↓ = Warming ↓

Both warming particles & cooling particles are emitted together!

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0.1% 6.5% 3.8% 1.1%0.2%

0.8%

19.0%

68.5%

Controllable emissions are dominated by transport & residential solid fuel

Open burning

41%

Residential: Biofuel18%

Residential: Coal4%

Residential: Other1%

Transport: Non-road

9%

Transport: Road16%

Industry11%

Power0%

Black carbon (BC) Organic carbon (OC)

Year 2000 estimates (Bond et al., GBC 2007 + updates for IPCC AR5)

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Expected sources of black carbon (BC)

Fraction "contained"

% of global "contained"0% 25% 50% 75% 100%

North America

Central/South America

Europe, Former USSR

Asia, Middle East, Pacific

Africa

Total

PowerIndustryTransport: RoadTransport: Non-roadResidential: OtherResidential: CoalResidential: Biofuel

Bond, Streets et al., JGR 109, D14203, doi:10.1029/2003JD003697

BC from solid fuels in residential sector BC from industry BC from transportation/diesel

developmentpath

Note: Energy-related only– excludes open burning (~equal)

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General rule about BC+OC emitters(for energy-related sources)

Emitter size

For large actors, poor efficiency = greater financial lossesimproved technology or controls are relatively more affordable

More fuel consumed

Greater efficiency

Reporting requirements more stringent

More information

More emissions per fuel

High emissions

from small

sources with little

information

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Example 1: Emissions from actual household cooking are much higher than lab results

Box plot of Emission Factors

0

2

4

6

8

10

12

14

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Field Tests(all)

Field Trad.Stove

Field Impr. w/o

chim.

Field Impr. w/

chim.

Lab Tests(all)

Venka-taraman& Rao(2001)

PM E

mis

sion

Fac

tor (

g/kg

) Field (ARACHNE)

Lab (ARACHNE)

Open Biomass (lit)

Roden et al., Atmos Env 43, 1170-1181, 2009

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Example 2: High-emitting vehicles contribute a lot to present-day emissions…

0 20 40 60 80 1000

0.2

0.4

0.6

0.8

1

Opacity

Frac

tion

of d

ata

Truck (200)Truck (26)

roadside inspection

lab –dynamometer tests

Subramanian et al., ES&T, 2009Winijkul et al., in prep

They are severely undersampled

in testing programs

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Example 2: …and affect future emissions even more

2010 2020 2030 2040 20500

500

1000

1500

2000a) A1B with superemitters

Year

PM

Em

issi

on (G

g/yr

)

2010 2020 2030 2040 20500

500

1000

1500

Year

b) B1 with superemitters

2010 2020 2030 2040 20500

100

200

300

400

500

600

700

Year

PM

Em

issi

on (G

g/yr

)

c) A1B without superemitters

2010 2020 2030 2040 20500

100

200

300

400

500

600

Year

d) B1 without superemitters

NONE OPAC EURO I EURO II EURO III EURO IV EURO V EURO VI SUPER

Yan et al., in prep

Emissions from“superemitters”

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Particles might go awayafter some development

Bond et al, GBC 2007

0500

100015002000250030003500400045005000

1850 1875 1900 1925 1950 1975 2000

BC e

mis

sion

s (G

g/ye

ar)

0100020003000400050006000700080009000

10000

1850 1875 1900 1925 1950 1975 2000O

C em

issi

ons

(Gg/

year

)

Latin America Middle East India Africa Other Asia/PacificEurope Former USSR China North America

Great DepressionTransition out of residential solid fuelGrowth in pulverized coal (BC+OC-clean)

Vehicle regulations

Steel! Steel! and railroads! Big question:Technology improvement

vs growth

Som

e N

orth

A

mer

ican

tra

nsit

ion

s

0

50

100

150

200

250

300

1850 1875 1900 1925 1950 1975 2000

En

erg

y co

nsu

mp

tio

n (

PJ) Natural Gas

Aviation fuelLight distillatMiddle distillaResidual oilCoalBiofuel

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Carbon particles: summary

Particulate Matter (PM)

Othergases

Carbondioxide (CO2)

Sectors & fractions of sectors: low CO2 but high black carbon Household solid fuel

(cookstoves) High-emitting diesels

Have significant contributions to climate-warming particles & gases But not on the climate-

change radar

Small sources matter, especially when emissions depend on process

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3. Sustainability – when?

How do we manageclimate change now

vsclimate change later?

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A devilish dilemma!

Reducing sulfur (cooling) emissions is… GOOD for health (immediate benefits) BAD for climate

(removes “mask” from warming)

Some “climate tipping points”look close

2007 Arctic sea ice, compared with median

Partial solution: Reduce emissions of warming air

pollutants?

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Reductions in greenhouse gases & black carbon are different solutions to climate change

Greenhouse gases(lifetime = decades)

Will build up in the atmosphere

Reduced emissions affect atmospheric concentration slowly

Affect snow and ice indirectly, by warming ocean & atmosphere

Black carbon(lifetime = days to weeks)

Will vanish eventually Reduced emissions

affect atmospheric concentration immediately

Can melt snow and ice directly, by changing their reflectivity

Long-term management challenge Possible “quick-fix” contribution

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Secretary of State Hillary Rodham Clinton: “There are also steps we must take to protect the environment. For example, we know that short-lived carbon forcers [sic] like methane, black carbon, and tropospheric ozone contribute significantly to the warming of the Arctic. And because they are short lived, they also give us an opportunity to make rapid progress if we work to limit them.”

Vice President Al Gore: “Soot, also known as ‘black carbon,’ from engines, forest fires and partially burned fuel was collecting in the Arctic where it was creating a haze of pollution that absorbs sunlight and warms the air. It was also being deposited on snow, darkening its surface and reducing the snow's ability to reflect sunlight back into space.”

April 6, 2009

April 27, 2009

Some people like fast action!

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Questions TO YOU:

How might we manage human impacts on climate in the near-term versus long-term?

How might we balance positive and negative steps toward sustainable energy use? example: Improve health but warm climate

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Take-home messages

Many pollutants affect climate… it’s more than just the “greenhouse effect”

A broad portfolio of solutions is available… “when”, “where” and “who” are considerations

Small sources matter, especially when emissions depend on process

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Questions?