Impacts of global change on crop production and food security

chapitre 45

International audience

anglais. Agricultural systems occupy approximately 24 % of Earth’s terrestrial surface.They have been ensuring a vital ecosystem service, since food production kept pace with population growth in the course of the twentieth century. Most of the past balance has been ensured through agricultural intensification. There currently is, however, an obvious mismatch between human population sizes (and thus food demand) and food production among regions of the world. Further, alarming signs indicate that maintaining a balance between the world’s population growth and its food supply in the coming decades will become a major challenge, especially in the context of global, including climate, change. Agricultural systems involve inflows and outflows, which determine their performances. Outflows include primary, desirable ones (e.g., crop yields) and secondary, often undesirable outflows (e.g., nutrient and pesticide losses to the environment). Inflows include non-substitutable ones, with essential roles for crop growth and plant metabolism (e.g., water, seeds, nutrients), while others are substitutable (e.g., labor, mechanization, pesticides). These inflows contribute to the growth-defining, growth-limiting, and growth-reducing factors, which determine three levels of plant production: potential, attainable, and actual. Three entry points to enhance the performances of agricultural systems are considered, through increasing (1) potential yields, (2) attainable yields, and (3) actual yields. The latter entry point, which involves improving crop health, has several advantages. One of them is that its likely impact is at least equivalent to increasing potential yields or attainable yields. Another critical advantage of increasing actual yields, especially through the improvement of crop health, is that it allows addressing not only the quantity of harvests but also their quality, thus fulfilling the goals of achieving both global food security and food safety. We propose that this conclusion applies to all levels of agricultural intensification, in particular intensive agricultural systems, (1) which are potentially more exposed to crop loss risks, (2) whose performances are particularly vulnerable to global change, and (3) which will continue to play a central role in global food security and safety.