Submitted to: Journal of Climate
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2016
Publication Date: 10/28/2016
Citation: Anapalli, S.S., Fisher, D.K., Reddy, K.N., Pettigrew, W.T., Sui, R., Ahuja, L.R. 2016. Vulnerabilities and adapting irrigated and rainfed cotton to climate change in the lower Mississippi Delta Region. Journal of Climate. 4(55):1-20.
Interpretive Summary: Overdependence on fossil fuels to satisfy human energy needs continues to increase greenhouse gas emissions into the atmosphere, leading to long-term climatic changes around the world. Prediction of possible impacts of changes in climate on agricultural production in the future continues to be a challenging task due to uncertainties in future temperature, rainfall, and CO2 patterns. Since local and regional geographic and environmental factors impact agricultural production, it is necessary to evaluate and develop mitigation and adaptation strategies for sustained productivity under changing environmental conditions. Researchers with the USDA ARS Crop Production Systems Research Unit at Stoneville, MS, and the Agricultural Systems Research Unit at Fort Collins, CO, undertook a study to investigate future rainfed and irrigated cotton production under various scenarios projected by global climate models, and to explore crop management and adaptation strategies to avoid adverse impacts on cotton production. Over a range of greenhouse gas emission scenarios, air temperatures and CO2 were projected to rise, with opposite and largely compensating effects on irrigated cotton yields under most scenarios (higher temperature decreased yield while higher CO2 increased yield). Yields were projected to decrease slightly under rainfed conditions due to insufficient water availability. Earlier than current normal plantings upto six weeks can boost or compensate for the yield loss under irrigate conditions. Under rainfed conditions, the early planting strategy only partially compensated for the yield losses, but providing a 4 inches of supplimental irrigation compensated it fully. So, climate change can bring more demands for irrigation water inputs into the cotton production systems in the MS Delta region.
Technical Abstract: Overdependence on fossil fuels for human energy needs continues to emitpotential greenhouse gases (GHG) into the atmosphere leading to a warmer climate over the earth. Predicting the impacts of climate change (CC) on food and fiber production systems in the future is essential for divising adaptations to sustain production and environmental quality. We used the CSM-CROPGRO-cotton v4.6 module within the RZWQM2 model for predicting the possible impacts of CC on cotton (Gossypium hirsutum) production systems in the lower Mississippi Delta (MS Delta) region of the USA.The CC scenarios were based on an ensemble of climate projections of multiple GCMs (Global Circulation Models) for climate change under the CMIP5 (Climate Model Inter-comparison and Improvement Program 5) program, that were bias-corrected and spatially downscaled (BCSD) at Stoneville location in the MS Delta for years 2050 and 2080. Four Representative Concentration Pathways (RCP) drove these CC projections:2.6, 4.5, 6.0, and 8.5, representing the increasing levels of the greenhouse gas (GHG) emission scenarios for the future, as used in the Inter-Government Panel on Climate Change-Fifth Assessment Report (IPCC-AR5). The cotton model within RZWQM2, calibrated and validated for simulating cotton production at the location, was used for simulating production under these CC scenarios. Under irrigated conditions, cotton yields increased significantly under the CC scenarios driven by the low to moderate emission levels of RCP 2.6, 4.5, and 6.0 in years 2050 and 2080, but under the highest emission scenario of RCP 8.5, the cotton yield increased upto 2050 but declined significantly in year 2080. Under rainfed conditions, the yield declined in both 2050 and 2080 under all four RCP scenarios; however, the yield still increased when enough rainfall was received to meet the water requirements of the crop (in about 25% of the cases). As an adaptation measure, planting cotton six weeks earlier than the normal planting date, in general, was found to boost irrigated cotton yields and compensate for the lost yields in all the CC scenarios. This early planting strategy only partially compensated for the rainfed cotton yield losses under all the CC scenarios, however, a 10 cm seasonal irrigation compensated for all the yield loss. So, climate change can bring more demands for irrigation water inputs into the cotton production systems in the MS Delta region.