Expanding US Cropland Emits Same as 36 New Power Plants

by Jon Cartwright (Physics World) Between 2008 and 2012 expansion of cropland in the US released carbon each year equivalent to the running of 36 coal-fired power plants, according to scientists in the US.

“Folks can easily see and understand how tropical deforestation removes carbon from the landscape and emits it to the atmosphere as carbon dioxide,” says Seth Spawn of the University of Wisconsin–Madison, US. “But in the US and other more temperate areas, land-use change disproportionately affects grassland ecosystems where – being stored underground – the vulnerable carbon is far less visible, but nevertheless abundant.”

In the past, carbon stored in grassland has also been hidden from scientific instrumentation. But recently, improved US maps of soil properties have enabled scientists like Spawn and colleagues to know where the carbon lies, and how it is affected by land-use change.

The researchers overlaid these maps with new, high-resolution maps showing the precise locations of nearly seven million acres of farmland that were first cultivated between 2008 and 2012. Then they used statistical models to estimate how much of the carbon at those sites was released to the atmosphere during cultivation.

Spawn believes that emissions like these could be avoided via land retirement and preservation programmes, if enrolment criteria were expanded to include the carbon buried in grassland.

For that reason, he and his colleagues are working with economists to see how biofuel policy could be driving emissions.

In addition, the researchers are integrating their emissions model into life-cycle assessments, to understand how emissions from land-use change are linked to those from products derived from crops. READ MORE