No abstract

This chapter reviews the global literature on impacts of climate change on agriculture and prospects for adaptation. Sensitivity of agriculture to climate change varies across the globe. Developing countries, where more than 800 million people are already undernourished, will be hardest hit. We review approaches for assessing the impact of climate change on agriculture and irrigation water requirements, and present recent progress in the assessment of adaptation measures. The challenges and constraints associated with climate change impact and adaptation research are critically discussed. The review leads to the conclusion that warmer temperatures will tend to reduce the crop yields in many regions, mainly due to reduction of crop duration associated with water stress during the critical stages of crop development. Although efforts have been made to understand better the climate-crop relationships, there is still limited understanding of the interactions between and relative importance of factors such as elevated ozone and CO2 levels, extreme weather conditions, weed variety, socio-economic changes and adaptation responses. Evaluation of diverse adaptation options from farm to policy level, and covering a range of scales and issues, including availability of resources, constraints and associated uncertainties, are essential to address adequately the impacts of climate and other changes on agriculture. Most of the published studies on adaption focus on modification of existing management practices to improve crop yield, using process-based models. Trade-offs between crop production and resource availability, which influence the farmer's decision making and profitability, have not received substantial attention. More effort is required to incorporate constraints (such as social, financial, institutional, technical and resources) and adaptive responses into the model frameworks that most studies used.