Could Uncertain Forest Inventories Hinder Carbon Markets?
September 9, 2009
A new RFF Discussion Paper highlights multiple incongruities in national forest measures from across the globe that could present a stumbling block for the development of international forest policy. “Without accuracy, appraisals of timber will be discredited, assays of biomass will be deceptive, and claims of sequestered carbon may be fraudulent,” writes Paul Waggoner in “Forest Inventories: Discrepancies and Uncertainties”
To take one example, according to a Food and Agriculture Organization assessment, El Salvador’s forested land shrank 14 percent from 1990 to 2000, while a separate study reported that its dense forested land area expanded 25 percent in the same timeframe. Furthermore, measurement uncertainties are inherent in even the best practices approved by the Intergovernmental Panel on Climate Change, currently the most authoritative source on climate science, says Waggoner.
Many of the discrepancies and uncertainties in total forest assessments can be expressed in four variables that make up the Forest Identity: area, stock density (or volume), biomass, and carbon. Because of the interrelationships of these variables, uncertainties in their measures compound and potentially result in a final estimate that has significantly more uncertainty than any single variable.
The purpose of pointing out these discrepancies, according to Waggoner, is not to develop a perfectly accurate measurement for forests, but rather to develop measurements that are good enough and consistent enough for parties interested in forests. Says Waggoner, “…the discrepancies and uncertainties in forest surveys must next be evaluated against standards of good enough for, say, scientific debates, timber sales, or carbon credits. Then economical methods for meeting those standards must be established.”