Climate change is no longer merely projected to occur in the indeterminate future. It has already begun to be manifested in the weather regimes affecting agroecosystems, food production, and rural livelihoods in many regions around the world. It is a real and growing challenge to the world at large and in particular to the scientific community, which is called upon with increasing urgency to respond effectively.The second volume in the ICP Series on Climate Change Impacts, Adaptation, and Mitigation, Handbook of Climate Change and Agroecosystems: Global and Regional Aspects and Implications is published jointly by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America and Imperial College Press. The ongoing series is dedicated to elucidating the actual and potential impacts of climate change, and to formulating effective responses to this global challenge. It is designed to inform, spur, and integrate the work of leading researchers in the major regions of the world, and to further international cooperation in this crucial field.