Climate geo-engineering with ‘carbon negative’ bioenergy

Nov 2008

This report represents a critical analysis of proposals for 'carbon negative' bioenergy, including biochar (agrichar) and bioenergy with carbon capture and storage, as a means of reducing atmospheric carbon dioxide concentrations and thus mitigating climate change. It includes a wider discussion about the impacts of large-scale bioenergy, and about the converging crises which threaten imminent collapse of our life-support systems.
The two bio-geoengineering proposals discussed in this paper are attempts to address one of the greatest threats humankind has ever faced – catastrophic climate change. We attempt to answer the question: Will such global bio-geoengineering ‘solutions’ help to stabilise climate or could they contribute to wide-scale collapse of our life support systems?
The evidence presented in Section 1 makes clear that The UN Framework Convention on Climate Change has failed in its intention. Atmospheric concentrations of greenhouse gases (GHGs) are already at dangerously high levels.
Section 2 considers the different proposals for achieving this. They look at the potential for rapidly reducing emissions of short-lived, high-impact greenhouse gases and aerosols which contribute net warming. They then give an overview of the two broad groups of geoengineering proposals for cooling the planet: Making the planet more reflective, and removing CO2 from the atmosphere. This paper is focused primarily on one aspect of this second grouping; the large-scale use of biomass as a substitute for fossil fuels, whilst simultaneously drawing down atmospheric CO2 by sequestering some of the carbon in the biomass, either underground or as charcoal to be added to soil.
Sections 3 and 4 consider in detail the two major proposals promoted by the aforementioned authors for achieving these outcomes. They are: bioenergy with carbon capture and storage (BECS), and bioenergy with biochar, a type of charcoal produced as a by-product of a particular biomass combustion technique.
Section 5 looks at the likely impacts of large-scale ‘carbon negative’ bioenergy on ecosystems, climate and people. James Hansen and several other proponents advocate large-scale bioenergy production based on low-input, high-biodiversity cultivation methods and on the use of forestry and agricultural 'waste', although Hansen has recently indicated in the media that he may also be looking at tree plantations. They conclude that any policies aimed at the scale of bioenergy use proposed will result in a dramatic expansion of industrial monocultures, even if this is not the intention of those scientists.

By: A. Ernsting, D. Rughani

 
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