03-21-2016, 11:03 AM
Quote:Re: Temperature Dependence of Ocean pH shows CO2 may not be driver of ‘ocean acidification’, 3/21/2016.
Professor Barrante writes,
… ocean pH has decreased from approximately 8.2 pH units to 8.1 pH units in the last 150 years. One explanation is that the increase in atmospheric carbon dioxide from the burning of fossil fuels is responsible. This is based on a law of physical chemistry, known as Henry’s Law, that states: if the partial pressure of a gas over a solution is increased, the concentration of the dissolved gas in the solution will increase. Since dissolved CO2 is a weak acid, one would expect the pH of the oceans to decrease. [¶] Describing Henry’s Law in this simple manner, however, is a very narrow interpretation of the boundaries of the system. For example, the above statement of Henry’s Law is only valid, if the temperature of the solution is constant.
This statement of Henry’s Law is about as weak a statement as possible, but nonetheless still valid. A stronger statement is that the concentration of a gas in a liquid is proportional to the partial pressure of the gas above the liquid, the proportionality being called Henry’s coefficient, which depends on the gas and liquid. But instead of Henry’s Law being “only valid if the temperature of the solution is constant”, Henry’s coefficient declines steadily with increasing temperature of the solution for most atmospheric gases in water, (N and H2 being exceptional). This behavior of Henry’s Law is what accounts for the ocean outgassing and absorption of CO2. This is what accounts for the natural carbon pump, driven by the inadequately named thermohaline circulation. IPCC calls the process both the solution pump and the solubility pump without ever mentioning Henry’s Law or its coupling into the THC. IPCC misses the massive carbon pump that regulates the concentration of atmospheric CO2 because it overwhelms all anthropogenic effects.
Henry’s coefficients are known to depend slightly on salinity of the liquid, but any dependence on pH is unknown. Prof. Barrante says imprecisely and ambiguously, Thermodynamic equilibrium constants are a sensitive function of temperature. This follows his introduction of the pH of the solution, suggesting he is not referring to Henry’s coefficients, but to the constants in his subsequent equations of marine carbon chemistry. See also IPCC, AR4, Box 7.3, Eqs. 7.1, 7.2, p. 529. Barrante can be applauded for introducing the phrase thermodynamic equilibrium, but in neither case, Henry’s Law nor carbonate chemistry, are these constants or coefficients properly called thermodynamic equilibrium constants. He then continues, saying
Ocean chemistry is complex, involving a number of important equilibria, that include the dissociation of carbonic acid (dissolved CO2), the buffering equilibria due to the presents of dissolved salts of bicarbonate and carbonate, the solubility of the sparingly soluble salt CaCO3, and the equilibrium between dissolved CO2 and the partial pressure of carbon dioxide in the atmosphere.
Thermodynamic equilibrium, which is defined as simultaneous thermal, mechanical, and chemical equilibrium, exists nowhere in the climate system, and that includes the hydrosphere. Thermodynamic equilibrium is the state of death and complete decay. Henry’s coefficients and the carbonate equations, including their constants, are only defined for thermodynamic equilibrium, a state that can only be approximated in laboratory experiments.
Acidification and the carbon pump are phenomena of the ocean surface layer, which IPCC, following the work of contributing author, computational oceanographer, Prof. David Archer, assumes to be in equilibrium. Imagine! The surface layer in equilibrium, when it is mixed with entrained air, churned by the wind, warmed by the Sun, cooled by IR radiation, and teaming with life to nominal depths between 100 and 300m, and far deeper at either pole where the THC plunges to the ocean bottom in winter!
By assuming some unnamed equilibrium exists at the surface of the ocean, IPCC manages to create a bottleneck to block dissolution of CO2 in the ocean. It even goes so far as restricting this bottleneck to anthropogenic CO2, ignoring the natural carbon cycle. Its misuse of carbonate equations causes ACO2 to remain in the atmosphere for about 30-35Kyrs (Archer (2005)) or many thousands of years (IPCC), waiting for CaCO3 precipitation to make room for new CO2. This bottleneck causes (anthropogenic) CO2 to accumulate in the atmosphere, essential to the story because man doesn’t emit enough CO2 to make even GCMs create alarming warming. This, in turn, is necessary to convert Keeling’s famous CO2 measurements at MLO from the effects of sitting in a seasonal wind-modulated branch of the plume of maximal outgassing at the outlet of ancient THC waters in the Eastern Equatorial Pacific into the contemporary master time series for determining the changing composition of the atmosphere in the story attributing CO2 and global warming to man. This equilibrium conjecture makes Henry’s Law newly dependent on the pH of the solvent with no experimental evidence. The consequence of acidification is merely a bonus bugaboo.
The atmosphere is not the imagined buffer reservoir for excess CO2, whether natural or anthropogenic. The mixed layer is the buffer, holding both aqueous and gaseous CO2, and allowing Henry’s Law to proceed apace, whatever the estimate might be for the effective coefficient for CO2.
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.
–William O. Douglas, U.S. Supreme Court Justice, 1952
–William O. Douglas, U.S. Supreme Court Justice, 1952