Ocean Desertification
February 13th, 2008 by SocProf and tagged Desertification, ecology, Environment, oceans
I didn’t know that was possible but apparently, this is happening thanks to global warming, according to Le Monde.
Le réchauffement de la planète entraîne une “désertification” croissante des océans
LE MONDE | 04.02.08
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Oceanic deserts are now a reality but one that is difficult to perceive, unlike land desertification which is visible to the naked eye. Oceanic desertification requires satellite technology to become visible. Specifically, oceanographers use Sea-viewing Wide Field-of-view Sensor (SeaWIFs) to map oceanic desertification and its evolution over the past ten years.
Over that period, oceanic deserts have increased 6.6 millions km2. As usual in the domain of assessing the impact of global warming, researchers had anticipated oceanic desertification but not to such an extent. Their models underestimated the phenomenon. It would also appear that the most affected areas are in the North and South Atlantic ocean, then North and South Pacific ocean whereas the Indian ocean has been relatively spared.
What explains oceanic desertification: as the surface temperature of the oceans increase, photosynthetic activity decreases. At the same time, as the surface water gets warmer, it mixes less with deeper, colder water. The problem is that it is in these mix areas that nutrients, necessary for the growth of phytoplankton are brought to the surface through marine currents.
However, because their models underestimate the expansion of oceanic desertification, the researchers are still open to the possibility of other variables at work. However, the fact that all four areas display the same trend despite different external constraints pleads in favor of the global warming as the overarching explanation.
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