ENHANCED SYSTEM MODELS AND DECISION SUPPORT TOOLS TO OPTIMIZE WATER LIMITED AGRICULTURE
Location: Agricultural Systems Research Unit
Title: Modeling the impacts of climate change on irrigated corn production in the central Great Plains
Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 3, 2012
Publication Date: April 27, 2012
Citation: Islam, A., Ahuja, L.R., Garcia, L.A., Ma, L., Anapalli, S.A., Trout, T.J. 2012. Modeling the impacts of climate change on irrigated corn production in the central Great Plains. Agricultural Water Management. 110:94-108.
Interpretive Summary: Increasing concentrations of the gases in the atmosphere (Carbon dioxide, methane, nitrous oxide and chlorofluorocarbons) are responsible for trapping outgoing energy and warming the keeping the earth. If the current rate of emissions of these gases continues unabated, climate scientists predict the global surface temperatures can increase by 1.1 to 6OC by the turn of the current century, leading to a climate unfavourable for human inhabitation. While the increase in carbon dioxide in the atmosphere helps plants enhance their photosynthesis rate (increased growth), the increase in temperature can adversely affect many of their growth and development processes leading to potential crop losses. In this study, we made an assessment of the potential consequences of such a climate change and elevated carbon dioxide levels on irrigated corn production in the Central Great Plains of Colorado using the cropping system model - RZWQM2. Climate change scenarios were generated by averaging 112 projections of the World Climate Research Programme (WCRP) Coupled Model Inter-comparison Project phase 3 (CMIP3) results, covering different possible current-future levels of greenhouse gas emission scenarios. Our study showed a decrease in corn yield, because the negative effects of increase in temperature dominated over the positive effects of increasing carbon dioxide levels. The mean decrease in yield f ranged from 11.3 to 14.0, 17.1 to 21.0, and 20.7 to 27.7% during the 2020s, 2050s, and 2080s, respectively. Because of the shortened crop growing period and the carbon dioxide effect of decreasing the ET demand, a decrease in the required irrigation is possible, during the crop growing period. Longer duration cultivars tolerant to higher temperatures may be one of the possible adaptation strategies.
The changes in temperature and precipitation patterns along with increasing levels of atmospheric carbon dioxide (CO2) may change evapotranspiration (ET) demand, and affect water availability and crop production. An assessment of the potential impact of climate change and elevated CO2 levels on irrigated corn (Zea Mays L.) in the Central Great Plains of Colorado was conducted using the RZWQM2 model. One hundred and twelve Bias Corrected and Spatially Disaggregated (BCSD) projections were used to generate four different multi-model ensemble scenarios of climate change: three of the ensembles represented the A1B, A2, and B1 emission scenarios and the fourth comprised of all 112 BCSD projections. Three different levels of irrigation, based on meeting 100, 75, and 50% of the crop ET demand, were used to study the climate change effects on corn yield and water use efficiency (WUE) under full and deficit irrigation. Predicted increases in mean monthly temperature during the crop growing period varied from 1.36 to 1.91, 2.14 to 3.43, and 2.73 to 5.43°C during the 2020s, 2050s, and 2080s, respectively, for the different scenarios. During the same periods, the projected changes in mean monthly precipitation varied in the range of -4.5 to 1.7, -6.6 to 4.0 and -11.5 to 10.2%, respectively. Simulation results showed a decrease in corn yield, because the negative effects of increase in temperature dominated over the positive effects of increasing CO2 levels. The mean decrease in yield for the four scenarios ranged from 11.3 to 14.0, 17.1 to 21.0, and 20.7 to 27.7% during the 2020s, 2050s, and 2080s, respectively. Because of the shortened crop growing period and the CO2 effect of decreasing the ET demand, there was a decrease in the required irrigation, during the crop growing period. Longer duration cultivars tolerant to higher temperatures may be one of the possible adaptation strategies. The amount of irrigation water needed to maintain the current yield for a longer duration corn cultivar, having the same water use efficiency as the current cultivar, is projected to change in the range of -1.7 to 6.4% from the current baseline, under the four different scenarios of climate change evaluated in this research.