Report says climate change will affect supply
OSLO, Norway (Reuters) — Global warming will cut average wheat yields by six percent for every degree of temperature rise, says a recent study.
It is a bigger-than-expected brake on food production in a hotter world.
The report, by a U.S.-led team of scientists, said a six percent drop would have been 42 million tonnes of 701 million tonnes of wheat production worldwide in 2012, highlighting a need to breed more heat-tolerant crops.
The study found that wheat yields have declined in recent decades in hotter locations such as India, Africa, Brazil and Australia, more than offsetting yield gains in cooler sites, such as parts of the United States, Europe and China.
Read Also
Powdery mildew can be combine fire risk
Dust from powdery mildew can cause fires in combines.
“Global wheat production is estimated to fall by six percent for each degree Celsius of further temperature increase,” according to the scientists, who used wheat crop computer models and field experiments.
They said developing new types of wheat to tolerate extra heat, especially in warm regions, would help limit damage from higher temperatures.
The study examined only temperatures. For example, it did not deal with the fact that more carbon dioxide, the main greenhouse gas emitted by burning fossil fuels, is an airborne fertilizer. It also did not try to assess possible changes in rainfall patterns.
“Wheat yield declines in response to temperature impacts only are likely to be larger than previously thought and should be expected earlier, starting even with small increases in temperature,” they wrote.
Jorgen Eivind Olesen, a professor at the University of Aarhus in Denmark who was one of the authors, said the focus on temperature alone meant the study “is not the complete picture.”
“Even so, in many parts of the world there would still be a decrease in yields,” even with small temperature rises, he said.
In March, the United Nations’ Intergovernmental Panel on Climate Change projected that wheat, rice and corn yields would fall overall with temperature rises of 2 C above late 20th century levels. It is a higher threshold than in the new study.
Average world temperatures have risen by about .9 C since the Industrial Revolution and are projected to rise by .3 to 4.8 C this century, depending on whether governments cut emissions or let them keep rising.
