Air Quality and Climate Change

Co-authors:Amos Tai, Eric Leibensperger, and Xu Yue, Daniel Jacob, Jennifer Logan

What U.S. city is this?

Loretta MickleyHarvard University

U.S. Air Quality Smog Blog, alg.umbc.edu/usaq

Weather has a large effect on U.S. air quality.

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Weather has a large effect on U.S. air quality.

Jan 23, 2013

Persistent temperature inversions this January over Northern Utah led to unhealthy air 11 out of 31 days.

Airnow; NASA Earth Observatory

cooler

warmer

Salt Lake City

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Both emissions and weather have been changing over the United States.

Thanks to Bryan Duncan

OMI NO2 data

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Temperatures have been increasing rapidly since the 1980s.

NASA GISS temperature analysis, GISTEMP

Contiguous US

-1

1

0Warming trend after 1980

Tem

pera

ture

ano

mal

y (o C

)

1880 2000

What do these trends mean for surface air quality?

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Number of ozone exceedances in Chicago and St. Louis looked promisingly low in recent years.

Number of days MDA8 ozone > 75 ppb

Chicago

St. Louis

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_ozc

ompa

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Airnow

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Drought + heat wave in 2012 ramped up number of ozone exceedances.

Number of days MDA8 ozone > 75 ppb

Chicago

St. Louis

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_ozc

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Airnow

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We know that surface ozone is sensitive to stagnation.

Stagnant air covers East.Clear skies.High temperatures.

Cold front moves through. Cool, clean air.

Leibensperger et al., 2010

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Cold fronts clear away pollution in central and eastern United States.

High ozone levels Clean air

Leibensperger et al., 2010

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Cyclones passing through Great Lakes/ Southern Canada region are associated with cold fronts .

Stagnant air. Cold front moves through.

Cyclone

Leibensperger et al., 2010

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Climate models predict decreasing trend in number of Great Lakes cyclones in warming atmosphere.

Num

ber o

f cyc

lone

s ov

er

Gre

at L

akes

regi

on

RCP 8.5

Turner et al., 2013

Climate model projection of JJA cyclone number over Great Lakes region.

30% decrease

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Climate models predict more persistent weather in future atmosphere over mid-latitudes.What are the implications for air quality?

As high latitudes warm, slower eastward progression of Rossby waves in the upper-level flow.

Francis et al., 2012

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Climate penalty for ozone air quality: Increased stagnation + high temperatures will likely increase surface ozone.

Climate generated by NASA GISS Model 3; Tai et al., 2013

-4 -2 0 2 4

2000-2050 change in JJA MDA8 ozone due to climate change.

ppb

D MDA8 JJA ozone

6 ppb

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Response of PM2.5 to changing meteorology is more complicated.

Observed relationships with Temperature (% K-1)

Observed sulfate correlates with temperature, but . . . .

nitrate anti-correlates with temperature.

Tai et al., 2010

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Net effect of 2000-2050 climate change on PM2.5 is small, at least when considering circulation changes.

2000-2050 change in annual mean PM2.5 due to changing circulation.

D annual mean PM2.5

Tai et al., 2012

Increased maritime flow

Increased stagnation

Changes are small, on the order of 0.5 mg m-3.

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Wildfires may become the dominant player in changing PM2.5 in future atmosphere.

Tai et al., 2012; Yue et al., 2013

Modeled 2050s response of surface PM2.5 to trends in circulation and in wildfires.

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Doubling of wildfire activity in warmer and drier 2050s significantly increases PM2.5 in the western U.S.

2000-2050 change in JJA mean organic carbon particles due to changing wildfires.

NASA GISS Model 3; Yue et al., 2013

D organic PM2.5

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NASA GISS Model 3; Yue et al., 2013

Increase in organic PM2.5 in 2050s is especially large during extreme wildfire events.

Cumulative probability of daily mean concentrations of organic particles

2050s

Present-day

doubling Projection shows doubling of organic particles during fire events over Rocky Mountains in May-October timeframe for the 2050s.

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Take home message 1

The response of air quality to climate change depends on trends in extreme events: stagnation, inversions, or wildfires.

Persistent temperature inversions this January over Northern Utah led to unhealthy air 11 out of 31 days.

cooler

warmer

Salt Lake City

Airnow; NASA Earth Observatory

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Take home message 2:

The climate penalty for ozone air quality could be large.

-4 -2 0 2 4

2000-2050 change in MDA8 JJA ozone due to climate change.

ppb

D MDA8 JJA ozone

NASA GISS Model 3; Tai et al., 2013

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Take home message 3:

Air quality in the West is vulnerable to changing wildfire in a warmer, drier climate.

Cumulative probability of daily mean concentrations of organic particles

2050s

Present-day

doubling Projection shows doubling of organic particles during wildfires over Rocky Mountains in 2050s.

NASA GISS Model 3; Yue et al., 2013