Realizing the social value of impermanent carbon credits

Efforts to avert dangerous climate change by conserving and restoring natural habitats are hampered by concerns over the credibility of methods used to quantify their long-term impacts. Here we develop a flexible framework for estimating the net social benefit of impermanent nature-based interventions that integrates three substantial advances: (1) conceptualizing the permanence of a project's impact as its additionality over time; (2) risk-averse estimation of the social cost of future reversals of carbon gains; and (3) post-credit monitoring to correct errors in deliberately pessimistic release forecasts. Our framework generates incentives for safeguarding already credited carbon while enabling would-be investors to make like-for-like comparisons of diverse carbon projects. Preliminary analyses suggest nature-derived credits may be competitively priced even after adjusting for impermanence. Nature-based solutions are essential to avoid climate crisis, yet how best to estimate their long-run effects is unclear. Here the authors propose a new dynamic accounting method that captures the impermanence of these carbon impacts, allowing investors to make robust comparisons across projects.