Mountain pine beetle upends the Canadian emissions picture?

The lastest Canadian greenhouse gas emissions data looks very different if Canadian forests are taking into consideration.

There was some rejoicing over the fact that Canada's GHG emissions grew by only 2 Mt CO2e (that includes CO2 plus other GHGs converted to "units" of CO2) or 0.25% from 2009 to 2010, despite the fact that the economy was rebounding from the recession. But if you include land cover, land use change and forestry, GHG emissions grew by 86 Mt from 2009 to 2010.

Why such a large change? According to the Canadian government model, forests went from a net sink of 17 Mt in 2009 to a net source of 72 Mt in 2010 (see Table 7-1 in NIR). If you

break the GHG balance of forests up by region, the driver of this change was the "Montane Cordillera", or #14 on the map to the left. These forests of western BC were a net source of 100 Mt. The only other net sources regions in 2010 were the "Boreal Shield West" (#9 at 22 Mt), the "Pacific Maritime" (#15 at 5.7 Mt) and the "Taiga Shield East" (#4 at 1.7 Mt).

There are large, natural year-to-year variations in forest carbon balance, so it's important not to read too much into the jump from 2009 to 2010. What the 2010 number does reflect, however, is the very large amount of carbon, in the form of dead wood, in BC that is waiting to be respired to the atmosphere (if we don't use sequester it in buildings). For that, we can largely thank the Mountain Pine Beetle, the outbreaks of which have been linked to climate change. From the National Inventory Report:

The upward trend in dead organic matter (DOM) decay since the year 2000 reflects the long-term, growing effect of past disturbances, especially insect epidemics that have left substantial quantities of decaying DOM. Over the last decade, insect epidemics have affected a total of over 56 Mha3 of managed forests, with 72% being located in the Montane Cordillera reporting zone and corresponding to the epidemics of Mountain Pine Beetle. In contrast, much of the interannual variability of the GHG budget of managed forests hinges on the occurrence and severity of fires.

Before you start screaming "cover-up", it is standard UN reporting practice, to not include land use, land cover and forestry in the "total" at the top of the GHG inventory tables. This is done for a number of legitimate reasons, not the least of which being that net emissions from forests must be estimated by models and, as I've said, the results vary from year to year because of climate variability. Nonetheless, it is striking that climate change, via its effects on Canadian forest, might be undoing the reported progress in curbing, or starting to curb is a better term, greenhouse gas emissions from some sectors of the Canadian economy.