(This is a continuing part of the mob blog on the carbon cycle. Tamino at Open Mind is posting on the latest trends in atmospheric CO2 concentrations and Simon Donner at Maribo wants to tell you about where all the carbon goes.)
There is an ongoing discussion in our mob blog about the role of forest fires. Horatio Algeranon lit the incendiary device. Tamino picked it out as particularly interesting and re-published the comment. Eli was wondering if there was a way to get at this.
Because most of the combustion occurs at relatively low temperature (relative here is still high enough to cook bunnies and little deer plus the occasional house) where the system is very much NOT optimized for emissions, forest fires are huge sources of CO (carbon monoxide). This is also true of agricultural burning, whether to clear ground for farming, or to reduce crop stubble after a season. The AIRS instrument can also track CO as well as CO2
The above map from September 2002 shows the major agricultural burning going on in Amazonia, Africa and Indonesia. This burning is quite interesting, also being a major source of tropospheric ozone in the Southern Hemisphere. Mongabay has a spectacular series of false color images showing how the burning in Africa follows the seasons. SAFARI and EXPRESSO are two measurement campaigns that have given us more information on this.
However, back to the point. There are two videos that all mice should see. The first shows CO emissions at the 500mb level in August and September of 2005. The second shows CO emissions from the huge fires in Alaska in 2004. They occured from May to Sept. Eli is not sure what the calibration is on the last one so it is hard to compare. On the other hand we can look at the CO2 readings at Barrow Alaska, and see if there is a jump in the period of the fires
Mar Apr May June July Aug SeptAnd we can do the same for Alert Station Canada which is downwind of the fires
2003 381.44 381.43 382.21 380.76 371.00 364.74 368.28
2004 382.17 383.80 383.47 380.50 371.75 366.50 367.86
Mar Apr May June July Aug SeptThe jump, if any is well within the range of natural variability which can be gauged from the Mar and Apr reading. Seasonal variability is 12-15 ppm at these high latitudes. Anyone interested in more information can go the linked cdiac site.
2003 380.90 381.39 382.38 381.02 373.78 367.97 368.55
2004 381.58 383.21 383.58 382.59 374.58 368.69 368.55
On the other paw, the issue is not so simple. Forest fires put CO2 into the air from burning, but they also can decrease CO2 emissions from soils after the fire by among other things destroying ground cover.