Media stories flooded the airwaves and the Internet in mid-August with claims of global warming threatening the world’s food supply. The media reported a new study showed rice yields have been dropping as temperatures warm. The new study, however, like other similar studies in recent years, actually concluded just the opposite.
BBC News reported, “Global warming is cutting rice yields in many parts of Asia, according to research, with more declines to come. Yields have fallen by 10-20 percent over the last 25 years in some locations.”
“This is the latest in a line of studies that suggest climate change will make it harder to feed the world’s growing population by cutting yields,” the BBC News story added.
Production Is Rising
In reality, the study cited by BBC News shows the rate of increase in rice yields has slowed by 10-20 percent. Yields haven’t fallen at all, and are in fact increasing, as they have been doing for decades. Rice yields are merely rising at a pace that is a little lower than the steep rate of increase in previous years.
In addition, the study did not rule out factors other than global warming as possible causes of the slight moderation in the rise of rice yields after the spectacular increases of recent years.
Higher temperatures have not been shown to reduce the rate of increase in other crop yields, which in fact appear to be benefiting from warmer temperatures. In addition, as warmer temperatures open more land to cultivation, a slight reduction in yield growth per acre may be more than compensated by the increase in land available for use.
Multitude of Crops Set Records
A multitude of crops other than rice have continued to set production records as atmospheric carbon dioxide levels and global temperatures continue their moderate rise. According to the U.S. Department of Agriculture, U.S. corn, soybean, wheat, peanut, sugar beet, bean, cotton, potato, rice, sorghum, barley, canola, flaxseed, and sunflower production have all set records within the past few years.
Scientists have found warmer temperatures have always benefited global crop production. This has been especially true during the modest warming of the past century, as the moderate increase in temperatures has spurred a corresponding increase in global precipitation.
As a study of 20th century Northern Hemisphere soil moisture published in the peer-reviewed International Journal of Climatology concluded, “The terrestrial surface is both warmer and effectively wetter.… A good analogy to describe the changes in these places is that the terrestrial surface is literally becoming more like a gardener’s greenhouse.”
James M. Taylor ([email protected]) is managing editor of Environment & Climate News.