Лекция: The oceans and atmospheric regulation

The atmosphere and the surface ocean waters are closely connected both in temperature and in CO2 concentrations. The atmosphere contains less than 1.7 per cent of the CO2, held by the oceans, and the amount absorbed by the surface ocean water rapidly regulates the concentration in the atmosphere. The absorption of CO2 by the oceans is greatest where the water is rich in organic matter or where it is cold. Thus the oceans are capable of regulating atmospheric CO2, of changing the greenhouse effect and of contributing to climate change. The most important aspect of carbon cycle linking atmosphere and ocean is the difference between the partial pressure of CO2 in the lower atmosphere and that in the upper oceanic layer. This results in atmospheric CO2 being dissolved in the oceans and in some of this being subsequently converted into particulate carbon, mainly through the agency of plankton, ultimately sinking to form carbon-rich deposits in the deep ocean as part of a cycle lasting hundreds of years. Thus two of the major effects of ocean surface warming would be to increase its СО2 equilibrium partial pressure and to decrease the abundance of plankton. Both of these effects would tend to decrease the oceanic uptake of CO2 and therefore to increase its atmospheric concentration, thereby producing a positive feedback (i.e. enhancing) effect on global warming. However, the operation of the atmosphere-ocean system is sufficiently complex that, for example, global warming may so increase oceanic convective mixing that the resulting imports of cooler water and plankton into the surface layers might exert a break (i.e. negative feedback) on the system warming.

 

Упражнение 11.

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Упражнение 12.

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