Connecting Air Pollution, Climate Change, and Health

J. Jason WestDept. of Environmental Sciences and

EngineeringUniversity of North Carolina

Smog Bothers Pedestrians, Los Angeles (1950s)

Hollywood Citizens News Collection, Los Angeles Public Library

A global picture

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How Many People Die From Ambient Air Pollution?Ozone-related mortality PM2.5-related mortality(*)

470,000 (95% CI: 140,000 - 900,000) 2.1 million (95% CI: 1.3 - 3.0 million)

(*) PM2.5 calculated as a sum of species (dark blue) PM2.5 as reported by 4 models (dark green) Light-colored bars - low-concentration threshold (5.8 µg m-3) Silva et al. (2013)

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Global Burden: Ozone-related mortality

Respiratory mortality , deaths yr-1 (1000 km2)-1,

multi-model mean in each grid cell , 14 models

Global and regional mortality per year

Regions Total deaths

Deaths per

million people

(*)North America 34,400 121Europe 32,800 96Former Soviet Union

10,600 66

Middle East 16,200 68

India118,00

0212

East Asia203,00

0230

Southeast Asia 33,300 119South America 6,970 38Africa 17,300 73Australia 469 29

Global472,0

00149(*) Exposed population (age 30

and older)

Silva et al. (2013)

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Global Burden: PM2.5-related mortality

CPD+LC mortality , deaths yr-1 (1000 km2)-1,

multi-model mean in each grid cell , 6 models

Global and regional mortality per year

Regions Total deaths

Deaths per

million people

(*)North America

43,000 152

Europe 154,000 448Former Soviet Union

128,000 793

Middle East 88,700 371India 397,000 715

East Asia1,049,00

01,19

1Southeast Asia

158,000 564

South America

16,800 92

Africa 77,500 327Australia 1,250 78

Global2,110,0

00665

1

(*) Exposed population (age 30 and older)

Silva et al. (2013)

Global burden of disease of outdoor air pollution

Lim et al., 2012

3.2 million deaths per year(95% CI:2.8 – 3.6 million)

WHO GBD 2010

Connections Between Air Pollution and Climate Change

1) Several air pollutants affect climate- Ozone (O3) is a greenhouse gas (GHG)- Aerosols scatter and absorb sunlight, and

affect clouds.

2) Changes in climate may affect air quality (of O3, PM, or other pollutants).

3) Sources of air pollutants and GHGs are shared – fossil fuel combustion.

4) Climate change may influence demands for energy, and therefore emissions.

Connections Between Air Pollution and Climate Change

Sources & Policies

Air pollutants

GHGs

Emissions Problems

Air pollution

ClimateChange

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Big Question: How can we plan to address air pollution and climate change in a coordinated way?

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Impacts

HumanHealth

IPCC, 2007

Radiative Forcing 1750-2005

Short-lived and Long-lived GHGs

OHHO2

NO NO2

hO3

NMVOCs, CO

Ozone Precursors Affect Both Ozone Air Quality and Climate Forcing

Urban Global

OHHO2

NO NO2

hO3

NMVOCs, CO, CH4

Ozone Precursors – Effects on Climate

Global Warming Potential (GWPH ): RF integrated to time horizon, H, following 1-year pulse emission: ∫H RFNOx /emissions / ∫H RFCO2/emissions

Patterns of GWP100 similar to normalized net RFs

-20% NOx-20% NMVOC -20% CO

[Fry et al., JGR, 2012]

Using methods from Fry et al. [2012] and Collins et al. [2013]

CO as Kyoto’s Forgotten Gas

20-yr GWP

100-yrGWP

[Fry et al., ACP, 2013]

4.07 [3.71 to 4.37]All regional GWP20 within 8.8% of Global GWP20

1.34 [1.26 to 1.44]All regional GWP100 within 7.5% of Global GWP100

OHHO2

NO NO2

hO3

NMVOCs, CO

Ozone Precursors Affect Both Ozone Air Quality and Climate Forcing

Urban Global

OHHO2

NO NO2

hO3

NMVOCs, CO, CH4

Simulate a 20% Reduction of Global Methane

2000 A2 2030 ∆O3

24-hr. 29.1 33.6 -0.82

8-hr. daily max. 31.8 37.1 -0.87

8-hr. population-weighted

49.4 61.7 -1.16

Global annual average ozone (ppb)

Change in surface 8-hr. ozone from a 65 Mton CH4 yr-1 reduction in methane emissions, at steady state (81% achieved by 2030 if implemented in 2010).

A2 Anthrop. emissions 2000-2030: CH4 +48%, NOX +70%

Jun-Jul-Aug

Annual Average

2030 Avoided Premature Deaths20% Global Methane Emissions

Reduction

Total 2030 avoided deaths: 30,200

West et al. (2006) PNAS

Comparing Monetized Health Benefits

with Control Costs ~10% of anthropogenic methane emissions can be reduced at a cost-savings.

Marginal cost of reducing 65 Mton CH4 yr-1 (20%) is ~$100 per ton CH4 (total cost is negative, IEA (2003)).

Marginal cost-effectiveness is $420,000 per avoided death for the 20% reduction.

Benefit is ~$240 per ton methane reduced (~$12 per ton CO2 equivalent) when deaths are valued at $1 million each.

Health benefits can exceed the costs of the 20% methane reduction.

Methane mitigation can be a cost-effective tool for global and decadal ozone management. West et al. (2006) PNAS

Shindell et al., Science, 2012

Co-benefits - Background

Reducing GHG emissions also reduces co-emitted air pollutants

-Air quality and health co-benefits shown to be substantial compared to GHG abatement costs.

“$2-175 / ton CO2 … all studies agree that monetized health benefits make up a substantial fraction of mitigation costs.” IPCC AR4

“$2-196 / ton CO2, and the highest co-benefits found in developing countries. These values, although of a similar order of magnitude to abatement cost estimates, are only rarely included in integrated assessments of climate policy.” Nemet et al. (2010)

-Most studies have focused locally or regionally.-Tend not to analyze future scenarios.-None has been global, using an atmospheric model.

Co-benefits of GHG Mitigation for Air Quality

Sources & Policies

Air pollutants

GHGs

Air pollution

ClimateChange

Objective: Analyze global co-benefits for air quality and human health via both mechanisms, in scenarios to 2100.

1) Immediate and Local

2) Long-Term and Global

HumanHealth

Results – PM2.5 Concentration

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36

38

2000 2020 2040 2060 2080 2100

Glo

bal

PM

2.5

(μg

m-3

)

Year

REFRCP4.5eREFm45e45m85

Global population-weighted, annual average PM2.5

Results – PM2.5 Concentration

2050

2100

Annual average PM2.5

Total changeRCP4.5 - REF

MeteorologyeREFm45 - REF

EmissionsRCP4.5 – eREFm45

Results – Ozone Concentration

Global population-weighted, max. 6 month average of 1 hr. daily max ozone

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50

52

54

56

58

60

62

2000 2020 2040 2060 2080 2100

Glo

bal

O3

(pp

b)

Year

REFRCP4.5eREFm45e45m85

Results – Ozone Concentration

2050

2100

Max. 6 month average of 1 hr. daily max ozone

Total co-benefit #2 Meteorology #1 Emissions

MeteorologyeREFm45 - REF

Total changeRCP4.5 - REF

EmissionsRCP4.5 - eREFm45

Results – Global Premature Mortality

PM2.5 co-benefits (CPD + lung cancer mortality) 2030: 0.4±0.2 2050: 1.1±0.5 2100: 1.5±0.6

Ozone co-benefits (respiratory mortality) 2030: 0.09±0.06 2050: 0.2±0.1 2100: 0.7±0.05

-10-9-8-7-6-5-4-3-2-101

2000 2020 2040 2060 2080 2100

Mo

rtal

ity

(Mill

ion

s yr

-1)

Year

O3 REFO3 RCP4.5PM2.5 REFPM2.5 RCP4.5

Global Projection of global population and baseline mortality rates from International Futures.

Results – Global Premature Mortality

Results – Valuation of Avoided Mortality

Red: High valuation (2030 global mean $3.6 million)Blue: Low valuation (2030 global mean $1.2 million)Green: Median and range of global C price (13 models)

Monetized Co-benefits

• Global average: $50-380 / ton CO2

• US and Western Europe: $30-600 / ton CO2

• China: $70-840 / ton CO2

• India: -$20-400 / ton CO2

• Higher than previous estimates: $2-196 / ton CO2

- Use future scenarios where population, susceptibility to air pollution, and economies grow.

- Account for chronic mortality influences of ozone as well as PM2.5.

- Account for global transport, and long-term influences via methane.

Major uncertainties

• Only adults >30 years accounted for. (low bias)

• Co-benefits of GHG mitigation would be greater had the reference scenario not assumed decreased air pollution.

• RCP emissions do not include primary inorganics (fly ash). (low bias for PM2.5)

• Coarse grid resolution for air pollution exposure. (low bias for PM2.5)

• Applying concentration-response functions from the present-day US, globally and into the future.

Alternative approach: value as avoided air pollution control costs.

Co-benefits: conclusions

• Global abatement of GHG emissions brings substantial air quality and human health co-benefits.

• Global GHG mitigation (RCP4.5 relative to REF) causes 0.5±0.2 million avoided deaths in 2030, 1.3±0.5 in 2050, and 2.2±0.8 in 2100

• Global average monetized co-benefits are $50-380 / ton CO2

– Greater than previous estimates

– Greater than abatement costs in 2030 and 2050.

• The direct co-benefits from air pollutant emission reductions exceed those via slowing climate change.