Global Warming Reduces World’s Major Crop Yields (TechNewsWorld.com) Global warming over the past quarter century has led to a fall in the yield of some of the most important food crops in the world, according to one of the first scientific studies of how climate change has affected cereal crops. Rising temperatures between 1981 and 2002 caused a loss in production of wheat, corn and barley that amounted in effect to some 40 million tons a year. [News Source]