If you’ve recently had a conversation about the world’s forests and climate change, then you’ve probably heard the figure "20 percent" thrown around. That number represents the amount of worldwide emissions currently attributed to deforestation and forest degradation.
If tropical rainforests have been a frequent topic of discussion in your social circles, maybe someone told you that more than 10 million hectares of rainforest were permanently logged or destroyed every year from 2000 to 2005. These figures represent important metrics for policymakers to understand the role forests play in environmental policy issues. Their widespread use is partially based on the assumption that scientists have accurate and consistent measurements of forest attributes from which they can derive such figures.
Forest measures and inventories, however, may not be as accurate and precise as scientists and policymakers would like. In his RFF discussion paper, Paul Waggoner highlights such discrepancies and uncertainties embedded in current forest measures. “Without accuracy, appraisals of timber will be discredited, assays of biomass will be deceptive, and claims of sequestered carbon may be fraudulent,” he writes in “Forest Inventories: Discrepancies and Uncertainties.”
His analysis comes at an opportune time as the Senate gears up to consider climate legislation and agencies like the Commodity Futures Trading Commission look to more closely regulate the nation’s carbon markets. As a major component of H.R. 2454, forest offsets will face more scrutiny about their veracity and quality in the coming months.
Waggoner showcases eleven different cases of major discrepancies in forest measures across the globe, including some within IPCC forest carbon accounting guidelines. One of the reasons for such uncertainty, he writes, is related to how forests are defined. The definition Waggoner cites—the Forest Identity—consists of four measures: area, growing stock density, biomass, and carbon. Uncertainties exist in each of these attributes and as they are combined to form the Forest Identity, their uncertainties aggregate and can result in significantly inaccurate final numbers.
So what’s the solution? Forest measures will never be perfect, nor will they have 0 percent uncertainty, but that is not why it is worthwhile to point out discrepancies. The point is to push toward acceptable levels of uncertainty in forest measures. As Waggoner points out:
Although perfect accuracy might seem the goal, it is not—at least not in the real world of affairs. Rather, the cost of improving accuracy makes good enough the goal. If the costs of surveying, monitoring, and verification exceed the consequent benefit or profit, regulation will fail and transactions abort in the long run…Thus 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.
In the mad rush toward using forest offsets to solve the world’s climate problems, voices of warning like Waggoner’s should not get lost in the din.
