Program

It has been established practice in the ocean sciences for more than 50 years to report on, and formulate models of, deep-sea biogeochemical properties as functions of depth. This is misleading and it has given rise to serious misunderstanding as to the impacts of climate warming on the ocean. The confusion first arose when oceanic oxygen consumption rates in the deep sea (R) were reported as exponential functions of depth as in the formulation depth with form R= R₀e^-αZ  where z is depth in km.  This resembles, but is not an identity for, a form of the classical Arrhenius equation K = Ae^-Ea/RT where T is temperature in Kelvins, R is the gas constant (8.314 JK^-1 mol^-1), and A is a pre-exponential factor. This deceptively simple approximation appeared to yield reasonable rates since oceanic temperature profiles themselves are typically quasi-exponential functions of depth and thus a pseudo-temperature dependence was latently present. In recent work we have shown that the rate of consumption of marine organic matter can be well represented by an Arrhenius function with an activation energy of 86.5 K J mol^-1 yielding a Q₁₀ of 3.63. This is very similar to the temperature dependence of the breakdown of organic matter in soils. From this we find that ocean warming of 2°C will yield an increase in the microbial rate of consumption of organic matter in the deep sea of 30%, and for 3°C warming by 47%. While ocean oxygen declines are the most obvious manifestation of this the primary process is the temperature dependence of microbial consumption of organic matter. In the delicately balanced deep ocean competition between microbes and higher animals for the chemical energy sinking down from the surface layers of the ocean microbes will universally gain a significant advantage in a warmer ocean, and the higher animals will face a reduced supply of food.