Geophysikalisches Kolloquium: Evaluating Climate Change Impacts from Ocean Chemistry

Climate change is driving an ocean that is warmer, more oxygen deficient, and higher in CO2; this combination can pose challenges for marine life. The O2 limit is traditionally reported as a simple mass concentration property without temperature, pressure or flow rate dependency. It may also be treated as a dynamic gas exchange problem for the animal analogous to gas exchange processes at the sea surface. A combination of temperature, salinity, hydrostatic pressure, flow rate over the respiratory surface, and oxygen concentration defines diffusive boundary layer transport at animal gas exchange surfaces and thus better defines the supply side ability of the ocean to match the demand side of an animal. As O2 levels decline an animal then at the limit an animal must either relocate or expend energy to increase flow (thin the molecular boundary layer) over its surface. From this analysis it is clear that temperature and pressure dependencies of diffusion and partial pressure create zones of greatest physical constriction on the diffusive transport in the boundary layer typically at around 1000 m depth, broadly coinciding with oxygen minimum zones. In some shallow and warm waters the enhanced diffusion and higher partial pressure from higher temperatures can slightly overcompensate for oxygen concentration decreases. However, since cold deep water regions comprise the vastly greater part of the ocean volume, the overall net effect of ocean warming and lower oxygen is expected to be negative for marine life in the mid-depth regions of the ocean.

Datum

19.04.2012

Uhrzeit

15:15 Uhr

Ort

Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg

ReferentIn

Peter Brewer, Monterey Bay Aquarium Research Institute, CA, USA

Chair

Jochem Marotzke
Tatiana Ilyina

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