A 'knowledge gap' remains in China about groundwater use and resulting emissions
Tiffany Stecker, E&E reporter
The practice of pumping groundwater for irrigation in China emits about 33 million metric tons of greenhouse gases per year, more than one-half of a percent of the country's total emissions.
China is the biggest emitter of greenhouse gases in the world, as well as the second-largest user of irrigation for growing crops. Nearly two-thirds of China's fresh water is diverted to agriculture.
The study from Chinese and British institutions -- the Chinese Academy of Sciences, the Chinese Academy of Agricultural Sciences, the University of East Anglia and Cranfield University -- is a follow-up to a paper published last year that found that energy use in the water sector is growing. Yet recognition and comprehension of the problem remain dim.
"We were trying to understand how water and the agricultural sector could adapt to climate change in the future," said Declan Conway, a professor at the University of East Anglia and author of both last year's study in Nature Climate Change and today's study in Environmental Research Letters. "There's potential to adapt to quite significant degree ... [but] there's very little information on that."
Kyle Gracey, a research scientist with the Global Footprint Network, is not surprised by the level of carbon emissions tied to electricity use for groundwater pumping.
"They tend to be the biggest source of the carbon footprint from the water sector," he said, although information is scant. "There is a knowledge gap here; it's poorly understood or recognized, the energy use [connection] to water."
Depleting the aquifers of northern China
Around 17 percent of China's greenhouse gas emissions come from agriculture. In the last two to three decades, China has exploited much more of its groundwater, Conway said. Advances in agricultural equipment technology, better and cheaper pumps, and less expensive fuel for those pumps made groundwater irrigation an attractive option for farmers. Pumping water from underground aquifers allows farmers more control over the amount of water used on crops, compared to irrigation from rivers and lakes.
"Farmers are very much at the mercy of the [surface] irrigation system," Conway said. As a result, the volume of groundwater use for crop irrigation has increased tenfold in the country since 1950, to 100 billion cubic meters per year in the 2000s.
The aquifers of the North China Plain -- the country's wheat-growing breadbasket -- have steadily been depleted from overuse, said Christine Boyle, CEO of Blue Horizon Insight, a company that provides research and analytics on the water risks and opportunities for conducting business in China.
Better efficiency through drip irrigation, sprinkler systems and smarter timing are methods for leaner resource management.
"Wheat doesn't need that much if you increase the strategic watering," Boyle said.
The government has increasingly shifted its focus to water efficiency. In January 2011, China chose to highlight water use as a theme in its Policy Document 1, which states priority initiatives for the upcoming year.
In its latest five-year plan, China pledged to increase irrigation water efficiency by 3 percent, while increasing total grain production by 13 percent and decreasing national energy production by 16 percent by 2015.
"There are potential tensions between the goals," Conway said. "At some places there are trade-offs." But the intention is promising, Boyle said.
"It's really too early to say the effectiveness of these particular policies," she said. "The solution isn't a mystery ... the solution is to decrease reliance on groundwater."
Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. www.eenews.net. 202-628-6500
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