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Bunk: Gaia Originator Suggests "emergency treatment for the pathology of global warming"
ScienceDave | September 27, 2007 at 12:19 amby
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So reads a recent letter to Nature from James Lovelock, of Gaia hypothesis fame, and Chris Rapley. In essence, they propose to make use of naturally occurring phenomena to, "help the planet heal itself" since it is impossible to "'heal the planet' directly."
So, what have they suggested?
In vast areas of the ocean, there exists little primary productivity - the conversion of inorganic nutrients (plant food) into organic molecules (plant tissue) via photosynthesis. 'Primary' simply refers to the bottom rung of the classical food chain - it provides the basal level of energy (i.e. things to eat) in a region.
Furthermore, the conversion of inorganic carbon (think CO2) into organic carbon (think non-CO2), and the subsequent 'falling out' of organic carbon below what is referred to as the thermocline (the top few meters/tens of meters - think hot and cold air - fluids of different densities don't like to mix unless energy is provided to mix them). This prevents that carbon from mixing with the atmosphere.
So, imagine to boxes stacked on top of one another. The top box represents the mixed layer, the bottom the deep ocean. Depending on where you are in the ocean, much of the inorganic nutrients that are converted into organic bits is eaten up by bacteria in the water (much like the day-old sushi in the discarded take out boxes sitting on my kitchen table). As it gets eaten, its converted back into carbon dioxide (just like we do), and is available to mix with the atmosphere.
However, a small amount sink below the thermocline lower box), where the underlying water is not in contact with the atmosphere through wind-driven mixing. Thus, this carbon is effectively sequestered from the atmosphere for around 500-1000 years (the time it takes the global ocean to turn over once).
Of course, there are bacteria munching away on this carbon too - however, due to increased pressure, colder temperatures, and the unique properties of CO2, the resulting gas doesn't seep through the water column back into the atmosphere. What I have just described is often referred to as the 'biological pump' (i.e. the conversion of inorganic carbon and other nutrients into organic molecules that are exported to the deep ocean).
So why do large areas of the ocean contain little productivity? Well, one reason - phytoplankton lack a particular nutrient they require to grow. Oceanographers make use of certain scientific 'tools' - one of them is called The Redfield Ratio (so named after the scientist who pioneered this work in the late 1950's, early 1960's). This ratio defines the amount of different required nutrients present in phytoplankton: for every 106 atoms of carbon(C), there are 16 atoms of nitrogen(N), and 1 atom of phosphorus(P) (i.e. it takes 1 atom of P to 'fix' 106 atoms of carbon)
Thus, if you measure the amount of total these nutrients present in a particular region of the surface ocean, you can determine which nutrient is likely limiting primary productivity. Since carbon has never convincingly been shown to limit growth (phytoplankton have unique ways of getting around this potential limitation by converting different chemical forms of carbon into usable forms), N and P are the next most likely culprits (besides a few other unique and important instances I will come to later).
But why are they limiting? What prevents vast amounts of N and P from getting into the surface ocean? Well, for a number of reasons. First, as phytoplankton grow, sink below the mixed layer (into the lower box), die, and are degraded by bacteria, their inner contents are converted back into the inorganic forms of their once-plant food. So what you are left with is a depletion of plant food in the surface, facilitated by a lack of mixing with deeper waters that hold the 'exported' inorganic nutrients required for phytoplankton growth.
What Lovelock and Rapley have proposed is the following: help break down the restraints the bottom layer of the thermocline impose on mixing deeper, nutrient rich waters with the surface by pumping large quantities of deep water to the surface. Thus, by increasing the amount of nutrients available to the overlying phytoplankton you can facilitate the removal of more carbon dioxide.
Sounds wonderful, but there are some serious flaws in this logic.
First, when you pump nutrient-rich waters t the surface, you also pump CO2-rich waters to the surface in the 106:16:1 ratio of C:N:P. Therefore, two possible results are likely to occur:
1) You effectively remove 100% of the nutrients pumped to the surface via the biological pump. The net result: no change in carbon removal, since the out-gassing of carbon dioxide from the deep water pumped to the surface will equal the carbon "biologically pumped" into the deep ocean.
2) Assuming you do not remove 100% of the nutrients through the biological pump, you end up providing a source of CO2 to the atmosphere instead.
Simply put, they are suggesting you come up with an imbalanced inventory without changing the absolute quantities involved.
Flawed logic indeed.
What's scary is, according to Quirin Schiermeier at Nature, a Mexican company is already developing such a project.
My unprofessional advice: don't invest.
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