Interesting article and the issues it deals with like much of what surrounds the GW debate remain uncertain.
The claim that the Amazon rain forrest is a great sink for CO2 has always bothered me as that claim is opposite to what some naturlists told me when I visited the rain forrest. They told me that the soils there were very poor and cutting the forrest to clear land for farming was in their opinion a bad idea. The concept they described was that the rain forrest quickly recycled and reused the dead plants and animals that inhabit it. Taking that a step leads me to believe that over long periods of time the rain forrests are not a sink for CO2.
For example, a big tree falls. It holds a lot of the CO2 it consumed while alive in the form of plant matter/cellouse. The now dead tree decomposes and releases that plant matter back into the environment as product of decay and that is quickly used by other plants, etc.
An interesting idea you may want to read more about is the concept of fertilizing the southern ocean so the phytoplankton will consume CO2 and when they die the carbon remains in the ocean.
A quote from this article:
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There are three major areas of the ocean where iron is a limiting factor in the growth of these plants: the sub-Arctic Pacific, the Equatorial Pacific, and the Southern Ocean. By adding iron to the ocean's surface, the tiny plants, called phytoplankton, increase in number in these locations. The plants need carbon dioxide -- an important greenhouse gas -- to live. The source of their carbon dioxide is the atmosphere, and more plants means more carbon dioxide is taken from the atmosphere. By enriching the plants with iron, carbon dioxide is transferred from the atmosphere to the ocean.
Iron was more plentiful in the atmosphere during the ice ages because the Earth was drier at that time. The dryness caused more dust to be picked up by the wind, and the dust contained iron, which then fertilized the ocean. More plant productivity in the ocean meant a reduction in carbon dioxide in the atmosphere.
Brzezinski, one of 17 principal investigators, took part in a major expedition to the Southern Ocean to test the theory. He spent 42 days at sea. With technician Janice Jones and graduate student Mark Demarest, both from UCSB, he took part in the dropping of a yellowish powder of iron sulfate, mixed with ocean water, into two areas of the Southern Ocean. The goal was to observe the growth and fate of the marine plants under such enriched conditions.
In order to simulate ice-age conditions, the scientists added iron to surface waters in two patches, each 15 kilometers on a side, so that the concentration of this micronutrient reached about 50 parts per trillion -- a 100-fold increase over ambient concentrations. Even at this low concentration, massive blooms of phytoplankton occurred at both locations. These blooms covered thousands of square kilometers, and were visible in satellite images of the area.
Each of these blooms consumed over 30,000 tons of carbon dioxide. Of particular interest to the scientists was whether this carbon dioxide would be returned to the atmosphere, or would sink into deep waters as the phytoplankton died or were consumed by grazing marine organisms.
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Here is a link to one such description of this process;
http://www.sciencedaily.com/releases/2004/04/040420013836.htm
DS
