How Will Global Warming Impact World Food Supplies?
`How Will Climate Change Impact World Food Supplies?A new study attempts to estimate the effects of climate change on global agriculture--and outlineways to mitigate its most dire consequencesThe people of East Africa once again face a devastating drought this year: Crops wither and fail fromKenya to Ethiopia, livestock drop dead and famine spreads. Although, historically, such droughts arenot uncommon in this region, their frequency seems to have increased in recent years, raising pricesfor staple foods, such as maize.This scenario may simply be a taste of a world undergoing climate change in the mid–21st century,according to a new report from the International Food Policy Research Institute (IFPRI), aWashington, D.C.–based organization seeking an end to hunger and poverty through appropriatelocal, national and international agricultural policies. By IFPRIs estimate, 25 million more childrenwill be malnourished in 2050 due to the impact of climate change on global agriculture."Higher temperatures and changes in precipitation result in pressure on yields from important cropsin much of the world," says IFPRI agricultural economist Gerald Nelson, an author of the report,"Climate Change, Agriculture, and Food Security: Impacts and Costs of Adaptation to 2050"."Biological impacts on crop yields work through the economic system resulting in reducedproduction, higher crop and meat prices, and a reduction in cereal consumption. This reductionmeans reduced calorie intake and increased childhood malnutrition."Nelson and his colleagues, working with funding from the World Bank and Asian DevelopmentBank, estimated global agricultural impacts by pairing IFPRIs own economic models for crop yieldswith climate models for precipitation and temperature from the U.S. National Center forAtmospheric Research and Australias Commonwealth Scientific and Industrial ResearchOrganization. Assuming a world that is slow to adapt to climate change and focused on regional self-reliance, the researchers found that children in the developing world—which are the countriesexpected to provide the bulk of population growth to nine billion or more by mid-century—will behardest hit."Its not economic development that matters in this case, its the location on the surface of the Earth,"Nelson notes. Without better crop varieties or other agricultural technology improvements, irrigatedwheat yields, for example, will fall at least 20 percent by 2050 as a result of global warming, andsouth Asia as well as parts of sub-Saharan Africa will face the worst effects.Even without climate change, population pressure alone will cause a spike in food prices withoutintervention, according to IFPRIs economic model. For example, without climate change, wheatprices might rise from $113 per metric ton in 2000 to $158 per metric ton in 2050—an increase of 39percent. Similarly, rice prices would soar by 62 percent, maize by 63 percent. But factoring inclimate change will boost wheat prices by at least 170 percent and rice by a minimum of 113 percent;the cost of maize will be at least 148 percent higher than at the turn of the century by mid-century.
Nor will the developed world go unscathed. Research published in the Proceedings of the NationalAcademies of Science in August noted that corn, soybean and cotton yields in the U.S. will dropprecipitously because of additional days where the temperature is above 30 degrees Celsius.Part of the problem is that the benefits of better plant growth, thanks to higher carbon dioxideconcentrations (plants use CO2 for photosynthesis) are more than offset by the impact of highertemperatures and differing precipitation. "If you grow a plant in a bell jar in a lab and increase theCO2 inside, the plants will perform better. [But] will those results translate into farmers fields?Evidence that weve been getting from farmers fields suggests perhaps not," Nelson says. And thatmeans fewer calories per person would be available in 2050.To prevent this agricultural crisis, Nelson estimates, would require an investment of at least $7billion per year in the most affected countries in Asia, Africa and Latin America for increasedagricultural research into, for example, drought-resistant crop varieties. "Crop and livestockproductivity–enhancing research, including biotechnology, will be essential to help overcomestresses due to climate change," the reports authors wrote.These areas will also need expanded rural road and irrigation infrastructure as well as improvementsto the efficiency of that irrigation.Climate changes glacial meltwaters will not aid such irrigation projects. "The glaciers, particularly inthe Himalayas, may disappear and cause some of the major rivers to become much more variable,which will have negative effects on yields in south Asia," Nelson notes. At the same time, traditionalseed varieties and livestock breeds that might provide a genetic resource to adapt to climate changeare being lost.Crop diseases and insect pests will also thrive in a hotter or more humid climate, and the report doesnot take into account issues such as current agricultural lands swamped by rising sea levels. "Theseare conservative estimates," Nelson adds. "Some elements we left out could make those numberseven higher."Even those areas that will benefit from a changed climate, such as a potential expansion in regionalclimates amenable to certain crops in Canada, for example, will not solve the problem. "The problemis youd have to grow corn on some pretty rocky soils," Nelson explains. "Its not clear that youd getmore production even if climate favors them."And expanding agriculture to feed more people may simply exacerbate climate change.Deforestation, largely driven by conversion to cropland, accounts for roughly 16 percent of globalemissions of the carbon dioxide warming the atmosphere.Oxfamhttp://www.oxfam.org.uk~