Canadian Forest Service Publications
Large inter-annual variations in carbon emissions and removals. 2010. Kurz, W.A. Pages 41-48 Invited Background Paper in H.S. Eggleston, N. Srivastava, K. Tanabe, and J. Baasansuren, editors. IPCC 2010, Revisiting the Use of Managed Land as a Proxy for Estimating National Anthropogenic Emissions and Removals, May 5-7, 2009, INPE, São José dos Campos, Brazil. IGES, Hayama, Japan.
Issued by: Pacific Forestry Centre
Catalog ID: 31934
The underlying assumption of the “managed land proxy” is that for the land use, land-use change and forestry (LULUCF) sector, the emissions and removals from managed lands are primarily due to anthropogenic activities. This proxy is currently used for the reporting of national greenhouse gas (GHG) budgets because there is no agreed-upon methodology to separate direct-human induced emissions and removals from those emissions and removals that are attributable to natural or indirect human-induced causes.
Forests are under varying degrees of direct human influences. In some large countries not all regions are accessible, populated or otherwise affected by direct human influences. The managed land proxy therefore provides a crude first approximation to distinguish between direct-human and other causes by stratifying the land area into managed and unmanaged components. While the managed land proxy has been useful in enabling the initial development of national greenhouse gas inventories for the LUCUCF sector, data now available raise several concerns. Here we focus on concerns for the managed forest.
First, in large countries with low population density (such as Canada, Russia, Australia and others) the contribution of natural and indirect-human induced processes to the net greenhouse gas balance of the managed forest can be very large and confound the contribution of anthropogenic activities.
Second, the interannual variability of the net GHG balance can be very large as a result of interannual variability in climatic conditions, and (in part as a consequence of this variability) in natural disturbances, including fires, insects, windthrow and drought.
Third, the predicted impacts of climate change include increases in natural disturbance rates and other extreme events, as well as increasing mal-adaptation of existing forest to the new climatic conditions. These climate change impacts are projected to increase the influence of indirect-human and natural processes on the net GHG balance in the managed forest. This will render the managed land proxy increasingly inaccurate and inappropriate as a means for reporting emissions and removals from anthropogenic activities.
Here we will briefly describe the factors contributing to large interannual variations in reported GHG net balances for the managed forest, and discuss ways in which these might be addressed such that anthropogenic emissions and removals are separated from those caused by natural and indirect-human processes.