The use of forest biomass for climate change mitigation: response to statements by EASAC

Date Dec 2019

Bulletins

The EASAC* press release “Experts call for international action to restrict climate-damaging forest bioenergy schemes”, and the scientific paper by Norton et al., that EASAC references, call attention to the critical need to ensure sustainability of forest bioenergy. We agree with a number of points in the paper, however, it also includes several errors, half-truths and generalisations, and draws some conclusions with which we disagree. The included response presents key facts about the use of forest biomass for climate change mitigation. Some key points:

  • Forests are generally managed as a series of stands of different ages, harvested at different times, to produce a constant supply of wood products. Climate effects of woody biomass should be considered at the estate/landscape rather than plot level – the time gap between harvest and regrowth of a single stand as defined in the Norton paper is less relevant. If annual harvest in the forest landscape does not exceed the annual growth of the forest there is no net reduction in forest carbon.
  • Sustainability governance is required to ensure that woody biomass used for energy makes a positive contribution to addressing climate change and other societal goals. A key requirement is that forests are regenerated and that carbon stock levels and carbon uptake capacity in the forest are at least maintained (which is required in the Recast of the EU Renewable Energy Directive, as well as in current Dutch legislation).
  • It is incorrect to determine the climate change effect of using biomass for energy by comparing greenhouse gas (GHG) emissions at the point of combustion. Instead, the biomass carbon flows and fossil GHG emissions associated with the complete life cycle of the bioenergy system need to be compared with the GHG emissions in the absence of bioenergy (both in the forest landscape and in the energy system).
  • Long-distance transport does not negate the climate benefits of woody biomass as a renewable energy source. For example, greenhouse gas emissions associated with transporting pellets between North America and Europe represent less than 5% of the full chain GHG emissions of hard coal.
  • Switching from coal to woody biomass reduces atmospheric CO2 over time scales relevant to climate stabilisation, with biomass from sustainably managed forests or land being part of the biogenic carbon cycle, in contrast to fossil carbon that increases the total amount of carbon in the atmosphere. The most important climate change mitigation measure is to transform energy and transport systems so that we can leave fossil carbon in the ground.
  • Managed forests produce wood for multiple products, not just bioenergy. The picture which is often presented that whole forest stands are cut for bioenergy alone is misleading. Forest management that maintains or increases carbon stocks, while also producing timber, fibre and energy, contributes to climate change mitigation by simultaneously storing carbon on land (with reduced risk of wildfires or diseases) and replacing carbon-intensive materials and fossil fuels. This has been repeatedly stated by IPCC.

* European Academies Science Advisory Council

 

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