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Meltwater is "the water released by the melting of snow or ice, including glacial ice and ice shelfs over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing." Thanks to global warming, this term has made the news in recent years. For example, in 2007, the BBC reported that melting glaciers in Asia's mountains could "affect an estimated 40% of the world's population, who rely on ice melt for crop irrigation and drinking water." In addition, "rising temperatures were already resulting in the thawing of permafrost in places such as Siberia. This was leading to the release into the atmosphere of methane, a potent greenhouse gas."

"The world has never faced such a predictably massive threat to food production as that posed by the melting mountain glaciers of Asia," adds Lester Brown of TreeHugger. "China and India are the world's leading producers of both wheat and rice?humanity's food staples. China's wheat harvest is nearly double that of the United States, which ranks third after India. With rice, these two countries are far and away the leading producers, together accounting for over half of the world harvest."