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All of our oceans, com­prised into one Global Ocean, are in a crit­i­cal state of health, accord­ing to a multi-​disciplinary panel of sci­en­tists. And it is far worse than they pre­vi­ously sus­pected. An inter­na­tional work­shop organ­ised by the Inter­na­tional Pro­gramme on the State of the Ocean (IPSO) at the Uni­ver­sity of Oxford ear­lier this year, brought together renowned sci­en­tists from a diverse back­ground. This inter– and multi-​disciplinary meet­ing was designed to con­sider the cumu­la­tive impact of mul­ti­ple stres­sors on the ocean, includ­ing warm­ing, pol­lu­tion, acid­i­fi­ca­tion, and overfishing.

The assess­ment made by the par­tic­i­pants shows a future for the oceans which is like our worst night­mare comes true. The world’s oceans are “at high risk of enter­ing a phase of extinc­tion of marine species unprece­dented in human his­tory” if no urgent action is taken to halt fur­ther declines in ocean health. The out­come of the work­shop has been reported recently, and a sum­mary is avail­able here.

The sci­en­tists say they observe changes of which the rate is exceed­ing their expec­ta­tions. Accel­er­ated changes, like melt­ing of the Green­land and Antarc­tic ice sheets, sea level rise, and release of methane trapped in the sea bed, in ways they did not expect to see for hun­dred years. But also over­fish­ing of species already beyond their lim­its is being observed. In addi­tion there is the prob­lem of the syn­er­gis­tic effect of some of the threats to marine life. Some pol­lu­tants, for exam­ple, stick to the sur­faces of tiny plas­tic par­ti­cles found in the ocean bed. This increases the amounts of these pol­lu­tants that are con­sumed by bottom-​feeding fish.

Although the IPSO report does not draw the final con­clu­sion that we have the sixth mass extinc­tion event at hand, but it does say that we are fac­ing a glob­ally sig­nif­i­cant extinc­tion event. In other words, the report sug­gests that the sixth mass extinc­tion event is likely to hap­pen. At a far higher rate than the pre­vi­ous five, with humankind being respon­si­ble, this time. The report notes that pre­vi­ous mass extinc­tion events have been asso­ci­ated with the same trends which are being observed now — dis­tur­bances of the car­bon cycle, and acid­i­fi­ca­tion and hypoxia (deple­tion of oxy­gen) of sea­wa­ter. The acid­i­fi­ca­tion of the seas due to CO2 being absorbed by the oceans will steadily increase if we do not bring down the green­house gas emissions.

There­fore some of IPSO’s rec­om­men­da­tions for imme­di­ate actions are: stop exploita­tive fish­ing, reduce the pol­lu­tion by plas­tics, agri­cul­tural fer­tilis­ers and human waste, and dras­ti­cally reduce green­house gas emissions.

(Sources: IPSO, 20.06.2011; BBC News, 20.06.2011)