What are the climate-change ramifications of clearing away forests? In a finding that could influence how climatologists forecast the pace of global warming – and strike a blow against some forms of bioenergy – UC Davis researchers say it all depends on what’s done with the wood taken out of the forests.
Writing in the journal Nature Climate Change, the Davis scientists say that if the wood from cleared forests is used to produce bioenergy or pulp for paper, all the carbon is released immediately. But if the forest wood is used as solid wood products – as lumber for housing, for instance – a big portion of the carbon could remain stored away for decades.
“We found that 30 years after a forest clearing, between 0 percent and 62 percent of carbon from that forest might remain in storage,” J. Mason Earles, a doctoral student with the UC Davis Institute of Transportation Studies and a lead author of the study, says in a statement. “Previous models generally assumed that it was all released immediately.”
To reach their conclusions, the Davis researchers looked at how forests are harvested in 169 countries. They found stark differences: In the coniferous forests of Europe, Canada and the United States, wood from cleared forests tends to become lumber; in the tropical forests of the Southern Hemisphere, the wood is used to generate power and to make paper.
“Carbon stored in forests outside Europe, the USA and Canada, for example, in tropical climates such as Brazil and Indonesia, will be almost entirely lost shortly after clearance,” the study states.
Bioenergy – biofuels and biomass – has its supporters, but the last decade has seen a succession of scientific reports calling into question its environmental impact. Just this spring researchers from Purdue and Stanford reported that the extra volatility that climate change could bring to the corn market would be further exacerbated by biofuel mandates, which they claimed could help to increase price volatility by about 50 percent.