Climate changes predicted to trigger food shortages across the world.
Rising temperatures during crop-growing seasons will pose a serious threat to food security by 2090, scientists report.
David Battisti from the University of Washington in Seattle and Rosamond Naylor from Stanford University in California analysed data from 23 global climate models produced for the Intergovernmental Panel on Climate Change's 2007 scientific analysis. Their results showed that there is a 90% chance that most of the tropics and sub-tropics will experience unprecedented seasonal average temperatures by the end of the twenty-first century.
The pair also used three case studies of areas that had experienced extreme heat weaves — in France, the Ukraine, and the Sahel region of Africa — to illustrate the scale of the impact on food production.
France felt some of the greatest impacts of the 2003 heat wave in Western Europe, seeing mean temperatures rise to 33 °C between June and August — nearly 4 °C higher than the country's average historical temperature for those months. Over this period, production of maize (corn) fell by 30%, fruit harvests declined by 25% and wheat harvests dropped by 21% compared with the year before.
The study, published in Science1, claims that by the end of the century, the temperatures experienced in the summer of 2003 will be the norm for the season in France.
Adapt or starve
Naylor says that investment will be key to avoiding significant food shortages. Developing crops that are tolerant to heat and drought, building appropriate irrigation systems and creating jobs outside the farming sector in the regions likely to suffer the most could all help to adapt to climate change, she suggests.
The conventional strategy of coping with food deficiencies in one part of the world by producing surpluses in other areas will be impossible, she adds. "In the future, the world may not be able to rely on temperate regions for food supplies, as even mid-latitude crops will suffer at very high temperatures unless adaptations are pursued there."
"Although temperate regions might benefit from some warming," Naylor adds, "the very high temperatures expected by the end of the century will lower yields, unless heat-tolerant varieties are developed."
Claudia Ringler, an agricultural economist at the International Food Policy Research Institute in Washington, DC, welcomes the study. "It is good that they focused on the impact of temperature change, as this is less well known. Most work so far has focused on the impact of reduced rainfall and drought on agriculture."
Ringler is working on a project to study the effects of climate change on actual crop yields. Although modelling might show potential yields dropping, yields could actually rise as a result of technological advancements, better management and improved irrigation systems, she says.
Battisti, D. & Naylor, R. Science 323, 240–244 (2008).
Related links in Nature Research
About this article
Cite this article
Gilbert, N. Temperature rises threaten global food security. Nature (2009). https://doi.org/10.1038/news.2009.9