'Peak soil' threatens future global food security
The challenge of ensuring future food security as populations grow and diets change has its roots in soil, but the increasing degradation of the earth's thin skin is threatening to push up food prices and increase deforestation.
While the worries about peaking oil production have been eased by fresh sources released by hydraulic fracturing, concern about the depletion of the vital resource of soil is moving center stage.
"We know far more about the amount of oil there is globally and how long those stocks will last than we know about how much soil there is," said John Crawford, Director of the Sustainable Systems Program in Rothamsted Research in England.
"Under business as usual, the current soils that are in agricultural production will yield about 30 percent less than they would do otherwise by around 2050."
Surging food consumption has led to more intensive production, overgrazing and deforestation, all of which can strip soil of vital nutrients and beneficial micro-organisms, reduce its ability to hold water and make it more vulnerable to erosion.
Such factors, exacerbated by climate change, can ultimately lead to desertification, which in parts of China is partly blamed for the yellow dust storms that can cause hazardous pollution in Asia, sometimes even severe enough to cross the Pacific Ocean and reduce visibility in the western United States.
The United Nations' Food and Agriculture Organization (FAO) has estimated that 25 percent of agricultural land is highly degraded, while a further 8 percent is moderately degraded.
Crawford said the degradation of soil could in theory lead to more land being bought into agricultural production, which would deal a serious blow to efforts to stem climate change, since clearing forests for farmland leads to a heavy net increase in greenhouse gases.
"If we keep treating our soil the way we do, we will have to convert about 70 percent of the earth's surface into agriculture to meet demand for food by 2050 (from about 40 percent now)," Crawford said.
That is in part because there will be many more mouths to feed. The United Nations has projected that global population will reach 9.6 billion by 2050, up from 7.2 billion last year.
Emerging nations are also embracing Western diets that include more consumption of meat, which will add further to the strain on agricultural resources.
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