335-8 Climate Change Impacts On US Crop Productivity in the Context of Multiple Global Changes During 1951-2099.
Wei Ren and Hanqin Tian
International Center for Climate and Global Change Research, and School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, 36849, USA
Crop production in the US is critical for the food supply here and around the world, which is approximately more than 30% of all wheat, corn, and rice on the global market. Over the past century, US agricultural ecosystems have experienced complex changes in multiple environmental factors, such as climate change, air pollution and land-use and land-cover change etc. Climate change (e.g. increasing temperature, more frequent and intensive extreme weathers), in particular, is posing unprecedented challenges to US agriculture. The majority of previous assessments explored the potential impacts of key climate variables (i.e. temperature and precipitation) on growth and productivity of agronomic crop species. Assessing climate change impacts on crop yield and food security in the US requires an integrated approach, in which the interactions between climate and other major environmental stressors should be considered together, such as worsening air pollution and intensive land management practices. By using the process-based ecosystem model DLEM-Ag (the agricultural module of Dynamic Land Ecosystem Model) driven by multiple environmental factors, we examined impacts of climate change and extreme events on crop productivity and yield in the conterminous US in the context of multiple environmental stresses during 1951-2099. The preliminary results show that, during 1951-2010, total crop productivity increased across the conterminous US with the large increase in many areas of the Great Plains while slight decrease occurred in some places of the North US. Nitrogen fertilizer use and land conversion play key roles influencing crop productivity. Climate variability and change led to the highest reduction rate of around 7% in crop productivity. Our projection results suggest that changes in total crop productivity would highly depend on future scenarios of climate and land use; high emission scenario (A2) could result in more reduction in total crop productivity, comparing to low emission one (B1).