Varying weather conditions seem to explain instability in crop yields, according to a new study. Researchers at the University of Minnesota Institute on the Environment were able to demonstrate how changes in climate influenced yield variability in corn, wheat, rice and soybeans for the past three decades. In the report published in the journal Nature Communications, climate variations account for more than 30 percent of crop yield variability in several regions around the world.
Statistics gathered from 13,500 political units worldwide from 1979 to 2008 were used in this study. Weather reports during these period were also included. Based on these, the researchers were able to analyse fluctuations in crop yield brought about by climate variability. About one-third of the yield variability every year can be attributed to climate change. This amounts to 22 million metric tonnes of maize, 3 million metric tonnes of rice, 9 million metric tonnes of wheat and 2 million metric tonnes of soybeans annually.
The impacts of climate variability, however, are different in the temperate and tropical regions. Highly productive areas are more affected than low-yielding regions. According to Deepak Ray, co-author of the study, regions with high crop yields contribute to food security by having large harvests due to pleasant weather conditions. However, low harvest can also cause food shortage globally if these productive regions are affected by unfavourable weather. Around two-thirds of yield variability in major crop-producing regions are caused by variable climate. These areas include Midwestern U.S., Western Europe, North China Plains and Japan.
Low-yielding regions rarely have productive harvests even during favourable weather, but these areas, which includes some parts of Asia and Africa, are barely affected by climate variability. The research team was able to identify the crop-producing regions that are greatly affected by climate variability. Instability in crop production, especially in important regions, can affect the food supply. Deepak Ray says, "The results of this study and our follow-up work can be used to improve food system stability around the world by identifying hot spots of food insecurity today as well as those likely to be exacerbated by climate change in the future."
James Gerber, Graham MacDonald and Paul West of IonE's Global Landscapes Initiative are co-authors of this study. The team plans to review more historical data to know whether the correlation has evolved in time and to determine the related climate variables.
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