Friday, June 22, 2007

The Biosphere and the missing carbon sink.

In an interesting paper in Science published this week, we see the question arising on the missing carbon sink of the atmospheric interchange of co2.We have discussed this here previously.

The global transport of carbon (partly in the form of CO2) among the large reservoirs is called the global carbon cycle. Carbon dioxide emitted into the atmosphere together with the uptake by the terrestrial sinks and oceans governs the carbon dioxide content observed by the global sampling networks. Currently 40-60% of the anthropogenically released carbon dioxide remains in the atmosphere. Our current knowledge is ambiguous whether the rest of the CO2 is being detached by oceans or by terrestrial sinks (soil or vegetation) (Baldocchi et al., 1996).Indeed the missing carbon sink around 20% of the gcc is one of the unanswered questions for the IPCC.

The rhectoric of the sustainable carbon neutral society modification experiment is indeed just that. Propaganda from lobbyists and politicians who want us to lock up forests,or reforestation programmes that which will have adverse daisyworld climatic effects in the future. Indeed increased forestry in non-tropical climates such as NZ have the effect of decreasing the albdeo (reflection of longwave radiation) and INCREASING local temperatures!

In the terrestrial biosphere vegetation accounts for 20% of the carbon sink,the vadose zone the soils and detritus materials 80%.

Here any policies that impact on the biosphere-atmosphere need to account qualitatively for the adverse effects prior to any policy that will have any equal adverse response.

As Science reports

Forests in the United States and other northern mid- and upper-latitude regions are playing a smaller role in offsetting global warming than previously thought, according to a study appearing in Science this week. The study, which sheds light on the so-called missing carbon sink, concludes that intact tropical forests are removing an unexpectedly high proportion of carbon dioxide from the atmosphere, partially offsetting carbon entering the air through industrial emissions and deforestation.

The Science article, "Weak northern and strong tropical land carbon uptake from vertical profiles of atmospheric CO2," was written by an international team of scientists led by Britton Stephens of the National Center for Atmospheric Research (NCAR).

To study the global carbon cycle, Stephens and his colleagues analyzed air samples that had been collected by aircraft across the globe for decades but never before synthesized. The team found that some 40 percent of the carbon dioxide assumed to be absorbed by northern forests is instead taken up in the tropics.

Most of the computer models produced incorrect estimates because, in relying on ground-level measurements, they failed to accurately simulate the movement of carbon dioxide vertically in the atmosphere. The models tended to move too much carbon dioxide toward ground level in the summer, when growing trees and other plants take in the gas, and not enough carbon dioxide up in the winter. As a result, scientists believed that there was relatively less carbon in the air above mid-latitude and upper-latitude forests, presumably because trees and other plants were absorbing high amounts.

This questions both the quantification of the available carbon sinks for both Kyoto and carbon taxation mechanisms(credits and penalties) it still shows how the mainstream scientists from modelworld fail to include the microbial carbon sinks which are responsible for 80% of carbon sequestion


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