Blog Action Day October 15 inspires me to ask: what is the impact of environmental and climate changes on the world food supply? A variety of causes and effects have been debated, and I've read a number of different analyses in the past. I'd like to know: do we expect widespread famine? Will the Great Plains dry up? Will there be mass starvation in India?
I found no simple answers. Here are a few of the areas and what I found.
Increase in average temperatures worldwide has already decreased crop yields. According to a Carnegie Institute study -- "on average, global yields for several of the crops responded negatively to warmer temperatures, with yields dropping by about 3-5 percent for every 1 degree F increase." Crops studied were those that are most important to worldwide nutrition: "wheat, rice, maize (corn), soybeans, barley and sorghum.... These crops occupy more than 40 percent of the world’s cropland, and account for at least 55 percent of non-meat calories consumed by humans. They also contribute more than 70 percent of the world’s animal feed." -- From "Crops feel the heat as the world warms," News Release, March 16, 2007.
Global warming in the future will continue to affect crop yields. Optimists claim that warmer summers and increase in CO2 levels would actually improve crop yields. However, field tests give a different result: "for all four of the world’s main food crops -- maize, rice, soybean and wheat -- the real-world fertilization effect was only half as great as predicted by the contained experiments." Further, increasing ozone levels will reduce crop yields. Prediction: even CO2 effects "will not prevent the world’s crop yields from declining by 10% to 15%." Occasional extremes of high temperatures could also lead to crop failures and famines in India. -- From Climate change warning over food production, 26 April 2005, NewScientist.com news service, Fred Pearce.
The Great Plains of the US produce significant food resources, and will experience significant impact from climate change. The Great Plains Climate Change Workshop, held in 1997, produced a long website concerning this issue. They state that: "the potential impact of climate changes is expected to affect winter snowfall, growing season rainfall amounts and intensities, minimum winter temperatures, and summer average temperatures. The combined effect of these changes in weather patterns and average seasonal climate will affect numerous sectors critical to the economic, social and ecological welfare of this region."
In India, government reports have warned of serious consequences from extreme weather. "Developing countries are right to be concerned about the negative impacts of climate change as they will suffer most," said a government spokesman. An Indian government report warned "that the cost of rising greenhouse gas emissions will fall predominantly on the poorest people. Global warming ... threatens to reduce India’s farm output by as much as a quarter." The spokesman said: "Climate change will increase the frequency of natural disasters. Long-term changes will lead to water scarcity, food insecurity and increased risk of malaria and major displacements of people and economic activity.'" -- From "Warming impacts Indian food supply," Sajeda Momin, March 24, 2006.
Corn-based ethanol has been promoted as a replacement for petroleum-based fuels. But this has a number of environmental consequences, and draws resources from the global food supply. "An O.E.C.D. report two years ago suggested that replacing 10 percent of America’s motor fuel with biofuels would require about a third of the total cropland devoted to cereals, oilseeds and sugar crops. Meanwhile, the environmental benefits are modest. A study published last year by scientists at the University of California, Berkeley, estimated that after accounting for the energy used to grow the corn and turn it into ethanol, corn ethanol lowers emissions of greenhouse gases by only 13 percent." -- From "The High Costs of Ethanol," editorial, New York Times, September 19, 2007.