Bad ocean forecast of the week

Dramatic expansion of dead zones in the oceans

From the above report at PhysOrg:

A team of Danish researchers have now shown that unchecked global warming would lead to a dramatic expansion of low-oxygen areas zones in the global ocean by a factor of 10 or more.

The New Scientist version of the story adds this detail:

Under the worst-case scenario, average ocean oxygen levels will fall by up to 40%, and there will be a 20-fold expansion in the area of "dead zones", like those already discovered in the eastern Pacific and northern Indian Ocean, where there is too little oxygen for fish to survive. Even in the mid-range scenario, dead zones would expand by a factor of 3 or 4. Cold, deep waters will also be affected if warming stifles the currents that deliver oxygen to greater depths.

Shaffer's projections suggest that the oxygen content in surface layers will dip to its lowest levels during the 22nd century, and in deep water a thousand years later. Recovery to pre-industrial levels will be very slow: "Even after 100,000 years, oxygen levels will only have recovered by around 90%," he says.

Go to the links for more details. Not exactly encouraging, as it shows what is potentially at stake if the warming skeptics are wrong. (And it is an additional risk to that of ocean acidification, which of itself is a major concern for future ocean health.)