Exploring the impacts of surface ozone and particulate matter

on global crop production

Luke Schiferl and Colette Heald

8th International GEOS-Chem Meeting

3 May 2017

[CEISIN GPWv3] [FAO GAEZ]

2010 Crop Production

[Mg km-2] [km-2]

2010 Population

80 % of global crop production

50 % of global population

Anthropogenic

Influence Since 1850

Particulate Matter (PM)

[GEOS-Chem v10-01] [µg m-3] [ppb]

Ozone (O3) Air quality issues

How does air quality (O3 + PM) affect our ability to

feed a growing human population?

Ozone Effects on Crop Production

Yield loss dependent on crop type:

maize rice wheat

increasing sensitivity

Ozone Crop Yield

Various empirical metrics help determine

impacts of ozone on crop yield.

Cumulative exposure: Mean exposure:

Species-specific

Relative Yield (RY)

[NASA Science Education]

Healthy

Ozone Damaged

40 ppb threshold

As used by Van Dingenen et al. [2009] and Tai et al. [2014].

Results: Current Air Quality Effects on Crop Production

−4.9% −6.9% −3.4%

∆ Production

Due to O3

Maize Wheat Rice

[Mg km-2] Current Emissions (2010)

GEOS-Chem v10-01

Particulate Matter Effects on Crop Production

PM

carbon fixed ≈ SW radiation × RUE

crop yield ?

gases

clouds

diffuse

direct

diffuse

direct

shortwave radiation

with PM

shortwave radiation

without PM

Diffuse fraction impacts a plant’s

radiation use efficiency (RUE)

[Greenwald et al., 2006]

from [Sinclair et al., 1992]

[Rochette et al., 1996]

varying

max ∆RUE

linear relationship

uncertain

[Mg km-2] Using max ∆RUE = 50% for PM

−0.4% −1.0% +0.6%

Net ∆ Due to

O3 and PM

Current Emissions (2010)

GEOS-Chem v10-01

Results: Current Air Quality Effects on Crop Production

−4.9% −6.9% −3.4%

∆ Production

Due to O3

Maize Wheat Rice

Production enhancement due to PM can offset negative effects

caused by ozone damage.

Variation is large between crop, region and sensitivity to DF.

+ RRTMG

Results: Varying PM Effects Based on DF to ∆RUE

Sensitivity to DF (maximum ∆RUE)

PM effect on crop

production is greatly

sensitive to relationship

between DF and ∆RUE.

Global Total

US+Canada China+SE Asia

Maize

Wheat

Rice

∆ Production

Due to PM [%]

∆ Production

Due to PM [%]

Sensitivity to DF (maximum ∆RUE)

0

100

50

[Mg km-2] Using max ∆RUE = 50% for PM

+0.9% +1.1% +0.5%

Net ∆ Due to

O3 and PM

RCP 4.5 Emissions (2050-2010)

Effects of Future Air Quality Changes

+1.5% +1.3% +0.9%

∆ Production

Due to O3

Maize Wheat Rice

While the net effect of future air quality on crop production largely

follows changes in O3, PM effects can reduce or override O3 effects.

Apply PM Radiation Effects in Crop Model

1) accounts for resource restrictions such as water and nitrogen

2) provides physiological constraints on growth

3) can include shortwave radiation effects on hydrology, etc

Current Emissions (2010)

Global Total Maize Wheat Rice Offline

Analysis

pDSSAT no water stress

no nitrogen stress

Apply PM Radiation Effects in Crop Model

1) accounts for resource restrictions such as water and nitrogen

2) provides physiological constraints on growth

3) can include shortwave radiation effects on hydrology, etc

Current Emissions (2010)

Global Total Offline

Analysis

pDSSAT no water stress

no nitrogen stress

pDSSAT with stresses

Maize Wheat Rice

Conclusions

Thank you to the MIT Martin Family Fellowship for Sustainability

and the Abdul Latif Jameel World Water and Food Security Lab (J-WAFS)

for funding this work.

Crop production enhancement due to PM can offset the negative effects caused by ozone damage in certain areas. Future improvements in air quality may have negative effects on crop production by reducing diffuse light. Failure to account for air quality influence in crop model may result in substantial model bias. Extend study to explore ozone effects and nitrogen cycling in crop model

Future Work