Air Pollution Impacts on Global Crop Productivity and Nitrogen Deposition AGU Fall Meeting December 17, 2014 Colette L. Heald Amos P.K. Tai (now at CUHK), Maria Val Martin (now at University of Sheffield)

Considering the Impact of Air Pollution and Climate on Global Food Security (in an era of rising food demand) tolerant sensitive AIR POLLUTION (Snap peas damage due to ozone exposure) CLIMATE (Illinois heat wave summer 2012)

Estimating the Climate and Air Quality Impacts on Global Crop Productivity From Historical Record Relative Yield [Mills et al. 2007] Wheat Ozone exposure (ppm-hour) T max T mean T high T base Day since 1 June °C°C based on Butler and Huybers [2013] Estimate yield-O 3 relationship from literature estimates of O 3 exposure indices Estimate yield-climate relationship from a MLR of FAO crop yields and NCEP/NCAR reanalysis

How Will Drivers Change in the Future? changes in maximum daily 8-h average (MDA8) O 3 (ppbv) changes in surface air temperature (K) Community Earth System Model (CESM 1.1) Simulation Warming climate, similar in both scenarios. Ozone projections reflect regional pollution control, but RCP8.5 includes large increases in methane (increases O 3 background) stippling=significant

Impacts of Climate Change and Ozone Pollution on Total Crop Production Future crop productivity very sensitive to ozone pollution & climate change. Uncertainty associated largely with future air quality. Pollution effect: ×10 15 kcal Climate effect: ×10 15 kcal Combined effect: ×10 15 kcal Pollution effect: ×10 15 kcal Climate effect: ×10 15 kcal Combined effect: ×10 15 kcal RCP4.5 RCP kcal ha

The rate of undernourishment in developing countries in 2050 increases by 50% due to climate and ozone. Impact of Ozone Pollution and Climate Change on Crop Production Around the World [Tai et al., Nature CC, 2014]

RCPs Project Important Changes in NO x and NH 3 Emissions: What are the Effects on Nitrogen Deposition? N deposition (RCP8.5) Emissions, Climate and Land Use

How N Deposition Will Evolve Compared to Critical Loads N deposition will be a threat for most ecosystems in Asia; some ecosystems in North America and Europe will be threated despite the large reductions in N emissions….. Kg N/ ha yr *Critical Loads from Pardo et al., (2011), Bobbink et al., (2010) and Bai et al., (2010). kgN ha -1 yr -1 Critical Load: “ input of a pollutant below which no detrimental ecological effects occur over the long-term according to present knowledge” (Padro et al., 2011)

Impact of Future N Deposition on Global Ecosystems [Val Martin et al, in preparation for GCB] Changes in anthropogenic emissions will drive future N deposition; contribution from climate and land use changes may be significant in some ecosystems…..

Conclusions Ecosystem productivity (crops and natural ecosystems) will continue to be at risk due to short-lived tropospheric “pollutants” (O 3 and reactive N) in the coming decades. We need to consider all the elements of global change (emissions, climate, and land use) in predicting future impacts. The time horizon under consideration is critical, particularly in an era of rapidly changing anthropogenic emissions. And the opportunities to alleviate these impacts are large!