If mankind is to adequately feed another three billion people by the middle of the century it will have to come to terms with the impacts of climate change on farming and food production.
 | Picture Gallery (click on the picture to start)Feeding an expanding world population takes a heavy toll on the planet. Click on the image to learn about sustainable ways to farm (Photo: Reuters) |
In some latitudes, notably northern Europe, Russia and Canada, a moderately warming planet could benefit agriculture in terms of lengthening the crop-growing season and boosting yields.
During the 2003 European heatwave, when crop yields in southern Europe dropped by 25 percent, yields increased in northern Europe, by 25 percent in Ireland and 5 percent in Scandinavia. Once temperatures rise by 3 to 4 degrees Celsius, however, those gains could be lost to increased incidence of crop disease and drought.
On a global scale, any benefits of climate change accruing to northern farmers will be outweighed by the toll climate change takes on the vast majority of the world’s food producers living in the developing world.
In late 1991 to early 1992, for example, Zimbabwe suffered a severe drought. This resulted in a fall in production of maize, cotton and sugarcane by 83 percent, 72 percent and 61 percent respectively. Zimbabweans lost nearly a quarter of their livestock, the animals either died of thirst or were slaughtered for food. Water shortages also led to the deterioration in quality and price of Zimbabwean tobacco.
The key factor, as ever, is water supply. In sub-Saharan Africa, for example, only 4 percent of arable land is currently irrigated.
As land becomes too hot and dry to grow crops, up to one million square kilometers of African farmland could be lost by 2050, report researchers from the International Livestock Research Institute and Waen Associates; that is more land than the United States uses to grow all its corn, soybeans, wheat, cotton, and rice combined
The U.S think tank The Brookings Institution estimates that African farmers on rain-fed land will lose 28 dollars per hectare per year for each one degree Celsius rise in global temperatures. Meanwhile, Latin American farmers would lose land value of 175 dollars per hectare, Chinese farmers on rainfed farms would lose annual net revenue of 95 dollars per hectare, and Indian farmers would lose 9 percent of their net revenue per hectare.
The numbers elsewhere are equally stark. Juzhong Zhuang, an economist at the Asian Development Bank, calculates that in four southeast Asian countries—Indonesia, the Philippines, Thailand, and Vietnam—rice yields could be halved relative to 1990 levels by the end of century. Yet by that time, there could be several hundred million more mouths to feed in the region.
The knock-on effects of agricultural decline are enormous. Following the 1991-92 droughts in Zimbabwe, for example, many households had to sell their goats that were intended as a form of savings to pay for their children's education.
editor: James Tulloch
publishing date: June 9, 2009
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