Melting glaciers will trigger food shortages

18:01 20 March 2008
NewScientist.com news service
Debora MacKenzie

The irrigation water vital for the grain crops that feed China and
India is at risk of drying up, as global warming melts the glaciers
that feed Asia's biggest rivers.

"The world has never faced such a predictably massive threat to food production as that posed by the melting mountain glaciers of Asia," says Lester Brown of the Earth Policy Institute.

The Ganges, Yellow and Yangtze Rivers in India and China are fed by rains during the monsoon season, but during the dry season they depend heavily on meltwater from glaciers in the Himalayas. The Gangotri Glacier in the Himalayas alone supplies 70% of the flow of the Ganges in the dry season.

The dry season is precisely when water is needed most to irrigate the rice and wheat crops on which hundreds of millions of people depend for their staple calories. But the Intergovernmental Panel on Climate Change reported last year that many Himalayan glaciers could disappear by 2035. According to Brown, Chinese glaciologists now estimate that two-thirds of the glaciers on the Tibet-Qinghai Plateau could be gone by 2060.
Severely diminished meltwater could make the flow of the three great rivers seasonal, warns Brown, who has long documented the effects of environmental damage on food production. China and India together produce more than half the world's wheat and rice, and the three river basins supply much of it, he says. TheYangtze irrigates half of China's annual rice harvest.

Flow river flow

The warning echoes another issued earlier this month by a former agriculture minister of Pakistan, Amir Mohammad, who warned that 60% of Pakistan's people depend on grain irrigated by the Indus river, which is also dependent on meltwater from Himalayan glaciers. "Melting of glaciers has already started affecting the water flow into Indus river system," he told local newpapers.

Meanwhile, much of the rest of the grain of China and India is fed by water that has for years been pumped from ancient underground aquifers faster than it can be replaced. The water tables under both the main grain-growing regions irrigated this way, the North China Plain and the Punjab, are sinking, says Brown.

Losing both sources of irrigation "could lead to politically unmanageable food shortages", he says, especially since rising populations in both countries require more food production, not less.

"In India, where just over 40% of all children under five years of age are underweight and undernourished, hunger will intensify and child mortality will likely climb."

Planet grain

The threat goes beyond the two countries directly affected. Grain is traded globally, and grain prices around the world are at record highs due to increases in demand all over the world.

"The alternative to this civilisation-threatening scenario is to abandon business-as-usual energy policies and cut carbon emissions 80% by 2020," says Brown. The first step, he says, is to ban new coal-fired power plants.

Ironically, China and India are the countries now planning to build the most new coal-fired plants. But Brown says China can double its current electrical generating capacity from wind alone.