A new study out of Norway demonstrates what opponents of biomass energy have been saying for years: logging forests for bioenergy leads to a permanent increase in atmospheric carbon dioxide.
Bjart Holtsmark’s study, “The outcome is in the assumptions: analyzing the effects on atmospheric CO2 levels of increased use of bioenergy from forest biomass,” published in Global Change Biology in 2012, provides compelling evidence that the expansion of industrial-scale biomass energy will exacerbate climate change.
Scientific studies focusing on the greenhouse gas emissions of burning forests for electricity and/or heat have evolved significantly over the past few years. Earlier studies assuming the carbon neutrality of biomass energy gave way to a more recent acceptance of a short-term carbon debt (decades to centuries) with long-term carbon neutrality, leading up to today’s conclusion that “wood fuels are not carbon neutral, neither in the long term nor in the short term.”
Holtsmark’s paper evaluates five previous studies on carbon dioxide emissions from biomass energy— Manomet Center for Conservation Sciences (2010), Cherubini (2011), McKechnie (2011) and Holtsmark (2012)—and adjusts some of their flawed methodologies, determining that “when the most realistic assumptions are used…an increased harvest level in forests leads to a permanent increase in atmospheric CO2 concentration.”
One previous error in methodology involved basing calculations of greenhouse gas emissions on a single logging event in a forest stand, as opposed to the more realistic scenario of multiple logging events. “IPCC [Intergovernmental Panel on Climate Change] documents, such as Chum et al. (2012), envisage a permanent increase in the use of bioenergy and, accordingly, a higher harvest rate,” explains Holtsmark, finding that “results change fundamentally” when multiple forest entries are taken into account.
Holtsmark also corrects the assumption that forests are always cut at peak growth, which is rarely the case due to economic pressures to log as quickly and often as possible. Further, Holtsmark highlights the need to measure carbon dioxide emissions against a baseline scenario of an unlogged forest “in which the trees are still growing, thus capturing CO2 from the atmosphere.”
“Technically speaking, this has never been a complicated issue,” said Chris Matera, founder of Massachusetts Forest Watch, whose organization has been calling attention to the health and environmental impacts of biomass energy in New England since 2007. “All that has ever been necessary to realize that increased cutting and burning of forests is not ‘carbon neutral’ is second grade math.”
“Ongoing logging to fuel ongoing biomass operations will add carbon to the atmosphere at the smoke stack,” Matera explained, “and increased removals will increase stress to forests and soils, and will likely reduce overall, long term growth rates thus also adding to atmospheric carbon levels – by absorbing less.”
“Instead, we need to do the opposite, let forests grow and expand as much as possible to clean up the mess we have made of our air and atmosphere.”
