Rising food prices are dependent on many factors, including population, income, and availability of supply (IFPRI 2010, p.2). This last factor is particularly affected by climate change. Climate disruption is already affecting prices for food and crops through impacts including changes in growing seasons, increasing extreme weather, rising sea levels, pest movement, and warming oceans.
The connections of U.S. agriculture and food security to global conditions are clearly illustrated by the recent food price spikes in 2008 and 2011 that highlighted the complex connections of climate, land use, demand, and markets. The doubling of the FAO food price index over just three months was caused partly by weather conditions in food-exporting countries such as Australia, Russia, and the U.S., but was also driven by increased demand for meat and dairy in Asia, increased energy costs and demand for biofuels, and commodity speculation in financial markets (NCA Chpt 6, p.244).
Many specific phenomena have been documented showing the impact of climate change on our food supply:
- Crop pests and pathogens have already been observed moving into new areas as our climate changes (Bebber et al. 2013).
- High nighttime temperatures affected corn yields in 2010 and 2012 across the Corn Belt (NCA Chpt 6, p.233).
- The 2012 drought, the United States’ most extensive drought in 25 years, destroyed large areas of cropland and led to increased prices (USDA 2012).
- From 1980 to 2008, growing seasons changed in most parts of the world, with temperatures exceeding standard natural variability. These changes had a significant effect on global maize and wheat production, reducing yields by 3.8 and 5.5 percent respectively (Lobell 2011).
- Higher seas make flooding in rice fields in vulnerable areas more likely, reducing yields and leading to higher prices (Chen et al 2012).
- Climate change is also projected to change the distribution of marine species, affecting production from fisheries (Sumalia et al 2011).
Studies have found a link between conflict and climate, through the destabilizing mechanisms of food and water insecurity. One meta-review found a correlation between increases of violence and increases in temperatures and rainfall (Hsiang et al. 2013), while another found “a causal association between climatological changes and various conflict outcomes” (Hsaing and Burke 2013). A third study cited climate change as “arguably one of the greatest challenges to food security,” particularly for “low-income individuals and communities” (Vermeulen et al. 2012), in addition to “exacerbating difficulties in obtaining sufficient food” for Inuit women (Beaumer et al. 2010).
In the future, the rising incidence of weather extremes will have increasingly negative impacts on crop and livestock productivity (NCA Chpt 6, p.241). One study comparing a number of difference models found that across the models agriculture would experience “strong negative effects from climate change” (Rosenweig et al. 2013). Climate disruptions are projected to lead to a 17 percent reduction in yield by 2050, relative to a scenario without climate change (Nelson et al. 2014). Adaptation may reduce losses somewhat, but will not be a substitute for mitigation.