Researchers ask: Is bioenergy really the answer?

In a public release by the University of Michigan (UM), research professor at the U-M Institute, John DeCicco argues that growing and harvesting bioenergy from crops is a ‘poor use of land’.

The UM researcher said that untampered green areas such as forests and fields isolate carbon dioxide effectively enough, and that they are ‘one of society’s best hopes’ for lowering the amount of greenhouse gases in the atmosphere.

Through an opinion piece in the current edition of Proceedings of the National Academy of Sciences, alongside president emeritus of the Cary Institute of Ecosystem Studies, William Schlesinger, the researchers call for relevant parties to ‘urgently’ realign their focus from bioenergy to untouched green areas or as they call it, “terrestrial carbon management”.

“The world needs to rethink its priorities about how to use the biosphere given the urgency of the climate problem and the risks to biodiversity,” DeCicco said.

“Current policies advancing bioenergy contribute to the pressure to convert natural land into harvested forest or cropland, but high quality land is a limited resource. For reducing atmospheric CO2, the most efficient use of ecologically productive land is to leave it alone, or reforest it. Let it act as a natural, long-term carbon sink.”

According to the release, DeCicco’s earlier findings indicated that biofuels are not inherently carbon-neutral ‘as they are widely purported to be’.

Instead, DeCicco argues that, for biofuels to be carbon neutral, the harvesting of biomass would have to ‘greatly’ speed up the net flow of carbon from the atmosphere back into the vegetation.

He alleges that otherwise, a profound amount of years can pass before this “debt” of excess carbon dioxide in the air is repaid with future plant growth.

In the opinion piece, both DeCicco and Schlesinger wrote, “All currently commercial forms of bioenergy require land and risk carbon debts that last decades into the future. Given the urgency of the climate problem, it is puzzling why some parties find these excess near-term CO2 emissions acceptable.”

The release detailed a 2016 study by DeCicco that found that just 37% of the carbon dioxide released from burning the biofuels was balanced out by increased carbon uptake in crops over the first eight years of the US biofuel mandate.

"By avoiding deforestation and by reforesting harvested areas, up to one-third of current carbon dioxide emissions from fossil fuels could be sequestered in the biosphere. Terrestrial carbon management can keep carbon out of the atmosphere for many decades,” the pair of researchers concluded.

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