Forest Leakage Risk Calculator

Leakage is the share of a project's claimed emission reductions that is cancelled out by emissions displaced beyond its boundary, and it is the reason a project with perfect internal performance can still deliver little net climate benefit. Activity-shifting leakage is the most direct form: the farmers, ranchers, or loggers excluded from the protected area continue the same activity nearby, so methodologies require monitoring of a defined leakage belt, commonly a buffer on the order of 10 kilometres around the project, and deduct the observed excess clearing. Market-effects leakage is indirect and cannot be observed by remote sensing at all, because withdrawing timber or agricultural land from supply raises prices and induces production somewhere in the wider economy; it is estimated with partial-equilibrium reasoning, and standards commonly apply fixed default deductions that can reach 40 or even 70 percent where the displaced commodity is judged fully substitutable. Ecological leakage covers physical spillovers such as altered hydrology, edge exposure, and changed fire behaviour on adjacent land, and is the least standardised of the three. Combined deductions in practice usually land between 10 and 40 percent of gross reductions. Two caveats are worth stating. Summing the three percentages additively, as here, is a simplification; some methodologies apply deductions sequentially to a shrinking base. And leakage can in principle be negative, since neighbouring landholders sometimes adopt the project's practices, though standards conservatively refuse to credit such spillover.

The term was imported from trade and climate economics, where carbon leakage described emissions migrating to jurisdictions without carbon constraints when one country acts alone. Forestry adopted it during the 1990s debates over joint implementation and offset crediting, and the IPCC gave it formal treatment for the land sector in its 2000 Special Report on Land Use, Land-Use Change and Forestry, which set out leakage alongside additionality and permanence as the structural problems facing forest carbon projects. Those three objections were decisive: they were the stated basis for excluding avoided deforestation from the Clean Development Mechanism when parties agreed the Marrakesh Accords at COP7 in 2001. Work through the 2000s tried to make the problem tractable rather than disqualifying. Reimund Schwarze and colleagues analysed carbon leakage mechanisms for forestry projects in 2002, distinguishing activity shifting from market response, and Stibniati Atmadja and Louis Verchot published a broad review of REDD+ leakage research and policy responses in 2012 that consolidated the typology now embedded in crediting standards. Voluntary market methodologies operationalised it through leakage belts, monitored reference areas, and fixed market-effect discount factors. The clearest structural response has been to raise the accounting boundary: jurisdictional and national REDD+ programmes internalise activity shifting automatically, because deforestation moved from one site to another inside the same jurisdiction still appears in the same ledger. That logic drove California's tropical forest standard and the move toward jurisdictional baselines in newer methodologies.