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Evaluating common carbon additionality tests and their suitability for inclusion in the Woodland Carbon Code



Carbon additionality is used to calculate the extent to which a project or activity results in net greenhouse gas emissions savings or sequestration above and beyond those that would have occurred even if the project had not taken place. Forest Research carried out a thorough review of the principles and methodologies for additionality assessments, providing the Forestry Commission with an evidence base for its Woodland Carbon Code.

Key findings and recommendations

  • Additionality is multi-faceted – at least 23 forms of additionality
  • Differences in tests relate to rigour-cost trade-offs rather than differences between ex-post and ex-ante crediting
  • Significant effects from “hidden” mechanisms seldom covered explicitly by additionality tests (e.g. gaming additionality)
  • Determining additionality is imprecise and is likely to remain controversial even where comparatively stringent tests are applied


Research summary, detailed findings and recommendations (PDF-2827K)

Forests and carbon: a review of additionality

Book chapter – Additionality of climate change mitigation activities (PDF-287K)

Research paper – “Additionality and climate change mitigation by the UK forest sector”, Gregory Valatin, Forestry (2012) 85 (4): 445-462

Funding and partners

Commissioned and funded by the Forestry Commission.


Ended in 2012.


Gregory Valatin