Friday, February 15, 2008

'Poised for significant reorganisation'

Scientists fear 'tipping point' in Pacific Ocean - a media report on a paper titled Emergence of Anoxia in the California Current Large Marine Ecosystem.

1 comment:

Thomas Goreau said...

The lead author of this study in the latest issue of Science, Francis Chan, was my undergraduate student thesis advisee. His thesis on the economic valuation of coral reefs, which was unfortunately never published, is far superior to anything in the literature.

The data they show in the paper shows progressively decreasing oxygen. The pattern of increasing anoxia is a global one, not confined to California. But what is unstated in this paper is what the cause of the decline is.

But it is likely to be global warming, which 1) has been shown by the CALCOFI long term study to have resulted in a rise of several degrees in California surface waters, which 2) decreases the solubility of oxygen, 3) increases the warm cap of surface water, and so prevents upwelling of cold deep nutrient rich waters to the surface, thereby 4) decreasing primary production, and 5) causing a large documented decrease in zooplankton, while 6) causing an increase in micorbial utilization of oxygen in respiration and carbon decomposition, while at the same time 7) nutrient and organic carbon loading from land based sources of pollution are increasing also.

This results in different cause of anoxia in zones overloaded from the land in places like Louisiana downstream from the Mississippi River mouth or the East China Sea, versus those affected more by physical circulation changes like the California Current system.