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Study: Agriculture's Carbon Output Higher Than Previously Thought

Over the span of history, agricultural uses have released nearly as much carbon into the atmosphere as actual deforestation. New problem areas are still appearing in places like Brazil.
September 12, 2017, 11am PDT | Philip Rojc | @PhilipRojc
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By depleting carbon stored in soil, agriculture has had a greater impact on the climate than previously supposed. According to a recent study, "land use changes associated with planting crops and grazing livestock have caused a loss of 133 billion tons of carbon from soil worldwide over the last 12,000 years, amounting to about 13 years of global emissions at their current levels."

Previous estimates, which were lower, relied on simple multiplication based on single-plot samples. This time, Chelsea Harvey writes, "the researchers were able to employ a large data set containing specific information on different soils from all around the world."

In places with "mature" agricultural economies, carbon losses from soil have been mitigated to a degree. "On a global scale, soil carbon losses have been speeding up since the industrial revolution, particularly in the 19th century. In the past 100 years, losses have tapered slightly, but still remain high, with the most significant emissions coming from new-world countries, such as Brazil, where large-scale agriculture is still expanding."

Harvey suggests that the study's findings could help pinpoint where sustainable land management techniques could do the most good, restoring carbon lost from soil to the ground.

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Published on Wednesday, August 23, 2017 in The Washington Post
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