Climate change and variability: impacts, vulnerabilities and adaptations in crop production systems

Climate change and climate variability are likely to have profound impacts on agricultural crop production systems. Increase in atmosphere carbon dioxide (CO2) level and also in temperature will significantly affect crop productivity as well as the areas planted to crops. The per disproportionate increase in variability of weather and climatic events (i.e. more frequent and more intense rainfall events, typhoons, droughts) threatens the sustainability of agricultural production. The effects and impacts of changing and variable climate can be evaluated through different methods, namely: (1) laboratory experiments using a phytotron where all environmental parameters can be controlled; (2) field experiments using temperature gradient tunnels, and growth chambers, and (3) process-based crop simulation modeling. In order to assess the climate change impacts on crop yields, a simulation study using process-based models was conducted. Crops considered in the study include the major food and feed crops and vegetables such as rice, corn, sugarcane, tomato, and peanut. Crop yields in selected locations in the Philippines were simulated under different climate scenarios characterized by increased temperature levels (0.5 deg C, 1.0 deg C, 1.5 deg C, and 2.0 deg C) and CO2 levels (i.e. 330 ppm or 1xCO2, and 660 ppm or 2xCO2). Simulation results show that crop yields are likely to decrease as temperature increases. Doubling of carbon dioxide enhances crop productivity even as temperature also increases. Vulnerability of crops differs, and the extent of climate change impacts vary from location to location. Areas planted to these crops are expected to be reduced in response to water scarcity associated with changing climate. Adaptations and mitigating measures in crop productions system may reduce the adverse impacts of climate change. A suit of adaptation and mitigation measures may include adjustments in crop management (e.g., planting calendar, planting density, crop variety, growing alternative crops, etc.), and improving water management irrigation efficiency. Institutional measures such as offering of crops insurance coverage and providing calamity fund may enhance risk sharing: pro-active measures such as improved seasonal climate prediction and implementing a knowledge-based crop forecasting system may prove to be more cost-effective.