THE PUSH towards biofuels is accelerating carbon dioxide release, not reducing it. Pursuit of this technology was creating a huge “carbon debt” that would take centuries to clear.
“If we continue on the path towards biofuels, we will effectively be burning the rainforest in our gas tanks,” stated Dr Holly Gibbs, a post doctoral researcher at Stanford University. She was speaking over the weekend at a session on climate change.
Biofuels such as ethanol derived from corn or sugarcane and biodiesel from oil palm were harming the situation because of changing agricultural practices, she said. This was particularly true for the tropics where rainforest was being cleared and burned to make way for agriculture.
This served to release stored carbon, but also took away the carbon absorbing potential of the forest. “This creates a carbon debt because the amount released is much more than that saved by biofuels,” Dr Gibbs said.
She calculated the “carbon payback” required to clear the debt. If the cleared land was used to grow cane or oil palm then the payback just to even the debt would take 40 to 120 years. Some land was being used to fill market gaps opened up as US farmers who increasingly divert their land away from soya and towards a corn crop destined for ethanol plants. Clearing rain forest to grow corn, soya or cassava meant the carbon payback could take from 300 to 1,500 years, Dr Gibbs said.
The overall picture was also bad according to Dr Chris Field, director of the Department of Global Ecology in the Carnegie Institution for Science in Washington. Increased coal use and deforestation in support of biofuel production had caused a rapid rise in carbon dioxide release.
He said the last benchmark on carbon release came with the 2007 publication of the fourth assessment report of the Intergovernmental Panel on Climate Change, but the situation had deteriorated significantly. The latest data suggested that we were “outside the entire envelope of probability in IPCC4.
It is beyond anything we had seriously considered in any model,” he said.
The most important driver for this change was the widespread adoption of coal-based electricity production, he suggested. Warming climate was also fuelling “feedbacks in ecosystems” such as the release of carbon from permafrost and deforestation. This and other feedback loops would dump an additional 500 billion to 1,000 billion tonnes of carbon into the atmosphere.
“We have high emissions and a less friendly system for picking up the higher emissions. We have two choices, we can start emission reductions now or make emission reductions more aggressive.”