Uncertainty estimation for Canada’s National Forest Carbon Monitoring, Accounting, and Reporting System
Greenhouse gas (GHG) inventories that are consistent with good practice, according to the Intergovernmental Panel on Climate Change (IPCC), are “those which contain neither over- nor underestimates, so far as can be judged, and in which uncertainties are reduced as far as is practicable.” Therefore, in any national GHG inventory, it is necessary to measure the uncertainty of the estimates and their contribution to overall uncertainty in the inventory. The Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) is the model used by Canada’s National Forest Carbon Monitoring, Accounting, and Reporting System (NFCMARS) to quantify the GHG inventory of the forest sector. Uncertainty in NFCMARS estimates of the carbon balance of managed forests in Canada arises from uncertainties in model inputs, parameters, and structure, as well as from human error.
In this project, Monte Carlo methods are used to obtain estimates of uncertainty directly from the model, an approach that has been recommended in a review of uncertainty assessments for carbon cycle models.
In GHG inventories, the purpose of uncertainty assessments is to guide efforts to reduce future uncertainty. Future work on the project will aim to attain this goal, with the understanding that, although some sources of uncertainty are more easily measured than others, they may not be those most easily reduced. In general, uncertainty consists of two components — accuracy and precision. This analysis attempts to measure the precision of model estimates. The accuracy of model estimates is improved annually by model and data changes suggested by new scientific evidence. However, the accuracy of estimates is very difficult to determine because there are no “true” reference values for most estimates in NFCMARS.
- Periodically updated estimates of the uncertainty of GHG sinks and sources in Canada’s managed forest, as reported in Canada’s national GHG inventory report
- Guidance for research that is likely to yield reductions in the uncertainty of reported GHG sinks and source in Canada’s managed forest
- Guidance regarding methodologies to generate error estimates for complex ecosystem simulation models (involving multiple data sources and poorly known error structures of both the model and the data)
Links to more information
Metsaranta, J.M. Uncertainty: A property of minds or of nature? Implications for forest carbon accounting. Presented at Statistical Issues For. Manage., May 2–4, 2011. Quebec City, QC.
Metsaranta, J.M. Experiences in quantifying the uncertainty of the estimates of Canada's National Forest Carbon Monitoring, Accounting, and Reporting System (NFCMARS). Presented at IPCC Expert Meeting Uncertainty Validation Emission Inventories. March 23–25, 2010. Utrecht, Netherlands.
Metsaranta, J.M. Forest carbon quantification with an emphasis on uncertainty estimation. Presented at Ont. Minist. Nat. Resour. Carbon Manage. Web Sem. Ser, November 12, 2009. Ontario, ON.
Metsaranta, J.M. and CFS Carbon Accounting Team. Quantifying the uncertainty of the carbon dynamics of Canada’s managed forest (1990–2007). Presented at Can. Carbon Program Annu. Meeting, February 26–28, 2010. Montreal, QC.
Metsaranta, J.M.; Kurz, W.A.; Stinson, G.; Neilson, E.T.; Rampley, G.J.; Smyth, C.; Shaw, C. Quantifying the uncertainty of the carbon dynamics of Canada’s managed forest. Presented at Int. Soc. Ecol. Modelling 2009 Conf., October, 2009. Quebec City, QC.