Grist: This isnt just about plants and animals. Its about people, its about societies, says Gene Takle, a convening lead author of the National Climate Assessments Agriculture chapter. Climate disruptions to our food system have already increased in the last 50 years, and will continue to do so. Many regions will experience declines in crop and livestock production from increased stress due to weeds, diseases, insect pests, and other climate change-induced problems.