# Learning lessons from over-crediting to ensure additionality in forest carbon credits

*2026-04-01 — paper*

Authors: Tom Swinfield, Abby Williams, David Coomes, Michael Dales, Patrick Ferris, Alejandro Guizar-Coutiño, James Hartup, Jody Holland, Sadiq Jaffer, Julia P. G. Jones, Miranda O. K. Lam, Srinivasan Keshav, Anil Madhavapeddy, Eleanor Toye-Scott, Thales A. P. West, Andrew Balmford


Independent evaluations have shown substantial over-issuance of REDD+ (Reducing
Emissions from Deforestation and Degradation) credits traded on the voluntary
carbon market. We synthesise these evaluations to estimate the additional
forest conservation achieved by first-generation REDD+ projects and to identify
mechanisms underlying over-crediting.

We combine six independent ex post evaluations of avoided deforestation
covering 44 REDD+ projects. These evaluations show that most projects reduced
deforestation, but that they claimed an aggregate of 10.7 times more avoided
deforestation than is justified by independent estimates.

This discrepancy is not driven by the choice of forest cover data, but by
selection bias in projects' control areas and modelling approaches. Although
recent initiatives that transfer assessment to unconflicted parties and
restrict methodological flexibility are critical, they are insufficient.

Ex-post certification against credible counterfactuals is necessary if carbon
markets are to represent causal reductions in deforestation.


DOI: 10.1038/s41467-026-71552-3
Classification: full
Venue: Nature Communications
Volume: 17
Issue: 1
URL: https://www.nature.com/articles/s41467-026-71552-3

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Canonical: https://anil.recoil.org/papers/2025-redd-evals
Type: paper
Tags: forest, sensing, spatial, redd, carboncredits, journal