14 - OCEAN DEOXYGENATION
Ocean deoxygenation is the expansion of oxygen minimum zones in the world's oceans as a consequence of anthropogenic emissions of carbon dioxide. The change has been fairly rapid and poses a threat to fish and other types of marine life, as well as to people who depend on marine life for nutrition or livelihood.
Oceanographers and others have discussed what phrase best describes the phenomenon to
non-specialists. Among the options considered have been ocean suffocation (which was used in a news report from May 2008), "ocean oxygen deprivation", "decline in ocean oxygen", "marine deoxygenation", "ocean oxygen depletion" and "ocean hypoxia".
Implications
Ocean deoxygenation poses implications for ocean productivity, nutrient cycling, carbon cycling, and marine habitats.
Most of the excess heat from CO2 and other greenhouse gas emissions is absorbed by the oceans. Warmer oceans cause deoxygenation both because oxygen is less soluble in warmer water, and through temperature driven stratification of the ocean which inhibits the production of oxygen from photosynthesis.
The ocean surface stratifies as the atmosphere and ocean warms causing ice melt and glacial runoff. This results in a less salty and therefore a less dense layer that floats on top. Also the warmer waters themselves are less dense. This stratification inhibits the upwelling of nutrients (the ocean constantly recycles its nutrients) into the upper layer of the ocean. This is where the majority of oceanic photosynthesis (such as by phytoplankton) occurs. (Wikipédia)
Ocean deoxygenation is the expansion of oxygen minimum zones in the world's oceans as a consequence of anthropogenic emissions of carbon dioxide. The change has been fairly rapid and poses a threat to fish and other types of marine life, as well as to people who depend on marine life for nutrition or livelihood.
Oceanographers and others have discussed what phrase best describes the phenomenon to
non-specialists. Among the options considered have been ocean suffocation (which was used in a news report from May 2008), "ocean oxygen deprivation", "decline in ocean oxygen", "marine deoxygenation", "ocean oxygen depletion" and "ocean hypoxia".
Implications
Ocean deoxygenation poses implications for ocean productivity, nutrient cycling, carbon cycling, and marine habitats.
Most of the excess heat from CO2 and other greenhouse gas emissions is absorbed by the oceans. Warmer oceans cause deoxygenation both because oxygen is less soluble in warmer water, and through temperature driven stratification of the ocean which inhibits the production of oxygen from photosynthesis.
The ocean surface stratifies as the atmosphere and ocean warms causing ice melt and glacial runoff. This results in a less salty and therefore a less dense layer that floats on top. Also the warmer waters themselves are less dense. This stratification inhibits the upwelling of nutrients (the ocean constantly recycles its nutrients) into the upper layer of the ocean. This is where the majority of oceanic photosynthesis (such as by phytoplankton) occurs. (Wikipédia)
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