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Biofuel forests for the future

Too little, too late
by Bill Schlesinger
Tue Apr 26th, 2016

The U.S. Senate seems determined to declare the substitution of wood for coal as a positive step to minimize the potential for global climate change. Under the Senate’s latest version of the energy bill, the various states, as they develop plans to reduce CO2 emissions to comply with the EPA’s Clean Power Plan, could count wood as a “carbon neutral” fuel. 

Somehow the Senators are able to overlook the fact that between now and 2030—the target for the President’s commitment to reduce CO2 emissions for the Paris accord—burning wood would substantially increase CO2 emissions to the atmosphere.  When trees are cut to provide biofuel for the generation of electricity, nearly all the carbon they contain is released to the atmosphere immediately.   And, because trees have lower energy content than coal, burning wood releases more CO2 per unit of energy generated than coal. 

The argument that trees are carbon-neutral inasmuch as they grow back after harvest is a moot point because most trees will not return to their preharvest stature before the 2030 target commitment of the Paris Climate accord.  Young trees grow faster than old trees, but it’s the comparative storage of carbon in the year 2030 that will determine whether trees are carbon-neutral or a source of CO2 to the atmosphere.  This is a carbon storage question, not an uptake or carbon sequestration question.  

Arguments that regrowing forests will pay back the carbon debt over 100 years are irrelevant; the most harmful effects of rapid global climate change will be “locked in” in 100-years time. 

Widespread harvest of mature forests for biomass energy will motivate the planting of short-rotation plantation forests to supply biomass. However, when we confront models of forest economics with data, they fail.  One-hundred and fifty years of forest management in Europe have not contributed to climate change mitigation.  Plantation forestry results in low-diversity stands with lower value for wildlife habitat.  Most studies showing a positive effect of burning wood to generate electricity ignore the uptake and sequestration of CO2that might have occurred if the forests had remained intact.

The forest products industry likes to cut trees, but trees are the most efficient way we know to remove CO2 from the atmosphere. 

References:

Mackey, B., I.C. Prentice, W. Steffen, J.I. House, D. Lindenmayer, H. Keith and S. Berry.  2013.  Untangling the confusion around land carbon science and climate change mitigation policy.  Nature Climate Change 3: 552-557.

Naudts, K., Y. Chen, M.J. McGrath, J. Ryder, A. Valade, J. Otto and S. Luyssaert.. 2015.  Europe’s forest management did not mitigate climate warming.  Science 351: 597-600.

Ricke, R.L. and K. Caldeira. 2014.  Maximum warming occurs about one decade after a carbon dioxide emission.  Environmental Research Letters 9: 124002

Root, H.T., and M.G. Betts. 2015.  Managing moist temperate forests for bioenergy and biodiversity.  Journal of Forestry 113: http://dx.doi.org/10.5849/jof.14-114

Schulze, E.D., C. Korner, B.E. Law, H. Haberl, and S. Luyssaert.  2012.  Large-scale bioenergy from additional harvest of forest biomass is neither sustainable nor greenhouse gas neutral.  Global Change Biology Bioenergy   doi: 10.1111/j.1757-1707.2012.001169.x

Ter-Mikaelian, S.J. Colombo and J. Chen. 2015.  The burning question: Does forest bioenergy reduce  carbon emissions?  A review of common misconceptions about forest carbon accounting.  Journal of Forestry 113: 57-68.