Chapter 8: Uncertainty assessment for quantifying greenhouse gas sources and sinks

Abstract

Quantifying the uncertainty of greenhouse gas (GHG) emissions and reductions from agriculture and forestry practices is an important aspect of decision�]making for farmers, ranchers and forest landowners as the uncertainty range for each GHG estimate communicates our level of confidence that the estimate reflects the actual balance of GHG exchange between the biosphere and the atmosphere. In particular, a farm, ranch, or forest landowner may be more inclined to invest in management practices that reduce net GHG emissions if the uncertainty range for an estimate is low, meaning that higher confidence in the estimates exists. This chapter presents the approach for accounting for the uncertainty in the estimated net emissions based on the methods presented in this report. A Monte Carlo approach was selected as the method for estimating the uncertainty around the outputs from the methodologies in this report as it is currently the most comprehensive, sound method available to assess the uncertainty at the entity scale. Limitations and data gaps exist; however, as new data become available the method can be improved over time. Implementation of a Monte Carlo analysis is complicated and requires the use of a statistical tool to produce a probability density function (PDF) around the GHG emissions estimate. From the PDF, the uncertainty estimate can be derived and reported.

Citation

Breidt, Jay; Ogle, Stephen M.; Powers, Wendy; Hoover, Coeli. 2014. Chapter 8: Uncertainty assessment for quantifying greenhouse gas sources and sinks. In: Eve, M.; Pape, D.; Flugge, M.; Steele, R.; Man, D.; Riley-Gilbert, M.; Biggar, S. Quantifying greenhouse gas fluxes in agriculture and forestry: Methods for entity-scale inventory. Tech. Bull. 1939. Washington, DC: U.S. Department of Agriculture, Office of the Chief Economist: 8-1-8.57.