Connecting Air Pollution, Climate Change, and Health J. Jason West Dept. of Environmental Sciences and Engineering University of North Carolina

Smog Bothers Pedestrians, Los Angeles (1950s) Hollywood Citizens News Collection, Los Angeles Public Library

A global picture

5 How Many People Die From Ambient Air Pollution? Ozone-related mortality PM 2.5 -related mortality(*) 470,000 (95% CI: 140, ,000)2.1 million (95% CI: million) (*) PM 2.5 calculated as a sum of species (dark blue) PM 2.5 as reported by 4 models (dark green) Light-colored bars - low-concentration threshold (5.8 µg m -3 ) Silva et al. (2013)

6 Global Burden: Ozone-related mortality Respiratory mortality, deaths yr -1 (1000 km 2 ) -1, multi-model mean in each grid cell, 14 models Global and regional mortality per year Regions Total deaths Deaths per million people (*) North America34, Europe32,80096 Former Soviet Union10,60066 Middle East16,20068 India118, East Asia203, Southeast Asia33, South America6,97038 Africa17,30073 Australia46929 Global472, (*) Exposed population (age 30 and older) Silva et al. (2013)

7 Global Burden: PM 2.5 -related mortality CPD+LC mortality, deaths yr -1 (1000 km 2 ) -1, multi-model mean in each grid cell, 6 models Global and regional mortality per year Regions Total deaths Deaths per million people (*) North America43, Europe154, Former Soviet Union 128, Middle East88, India397, East Asia1,049,0001,191 Southeast Asia158, South America16,80092 Africa77, Australia1,25078 Global2,110, (*) Exposed population (age 30 and older) Silva et al. (2013)

Global burden of disease of outdoor air pollution Lim et al., 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 (O 3 ) is a greenhouse gas (GHG) -Aerosols scatter and absorb sunlight, and affect clouds. 2)Changes in climate may affect air quality (of O 3, 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 EmissionsProblems Air pollution Climate Change 1 23 Big Question: How can we plan to address air pollution and climate change in a coordinated way? 4 Impacts Human Health

IPCC, 2007 Radiative Forcing

Short-lived and Long-lived GHGs

OHHO 2 NONO 2 h O3O3 NMVOCs, CO Ozone Precursors Affect Both Ozone Air Quality and Climate Forcing Urban Global OHHO 2 NONO 2 h O3O3 NMVOCs, CO, CH 4

Ozone Precursors – Effects on Climate Global Warming Potential (GWP H ): RF integrated to time horizon, H, following 1-year pulse emission: ∫ H RF NOx /  emissions / ∫ H RF CO2 /  emissions Patterns of GWP 100 similar to normalized net RFs -20% NO x -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-yr GWP [Fry et al., ACP, 2013] O 3 + CH 4 O 3 + SO [3.71 to 4.37] All regional GWP 20 within 8.8% of Global GWP [1.26 to 1.44] All regional GWP 100 within 7.5% of Global GWP 100

OHHO 2 NONO 2 h O3O3 NMVOCs, CO Ozone Precursors Affect Both Ozone Air Quality and Climate Forcing Urban Global OHHO 2 NONO 2 h O3O3 NMVOCs, CO, CH 4

Simulate a 20% Reduction of Global Methane 2000A2 2030∆O3∆O3 24-hr hr. daily max hr. population- weighted Global annual average ozone (ppb) Change in surface 8-hr. ozone from a 65 Mton CH 4 yr -1 reduction in methane emissions, at steady state (81% achieved by 2030 if implemented in 2010). A2 Anthrop. emissions : CH 4 +48%, NO X +70% Jun-Jul-Aug Annual Average

2030 Avoided Premature Deaths 20% 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 CH 4 yr -1 (20%) is ~$100 per ton CH 4 (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 CO 2 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 CO 2 … all studies agree that monetized health benefits make up a substantial fraction of mitigation costs.” IPCC AR4 “$2-196 / ton CO 2, 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 Climate Change Objective: Analyze global co-benefits for air quality and human health via both mechanisms, in scenarios to ) Immediate and Local 2) Long-Term and Global Human Health

Results – PM 2.5 Concentration Global population-weighted, annual average PM 2.5

Results – PM 2.5 Concentration Annual average PM 2.5 Total change RCP4.5 - REF Meteorology eREFm45 - REF Emissions RCP4.5 – eREFm45

Results – Ozone Concentration Global population-weighted, max. 6 month average of 1 hr. daily max ozone

Results – Ozone Concentration Max. 6 month average of 1 hr. daily max ozone Total co-benefit #2 Meteorology #1 Emissions Meteorology eREFm45 - REF Total change RCP4.5 - REF Emissions RCP4.5 - eREFm45

Results – Global Premature Mortality PM 2.5 co-benefits (CPD + lung cancer mortality) 2030: 0.4± : 1.1± : 1.5±0.6 Ozone co-benefits (respiratory mortality) 2030: 0.09± : 0.2± : 0.7±0.05 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: $ / ton CO 2 US and Western Europe: $ / ton CO 2 China: $ / ton CO 2 India: -$ / ton CO 2 Higher than previous estimates: $2-196 / ton CO 2 - Use future scenarios where population, susceptibility to air pollution, and economies grow. - Account for chronic mortality influences of ozone as well as PM 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 PM 2.5 ) Coarse grid resolution for air pollution exposure. (low bias for PM 2.5 ) 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 $ / ton CO 2 –Greater than previous estimates –Greater than abatement costs in 2030 and The direct co-benefits from air pollutant emission reductions exceed those via slowing climate change.