image: US DEP
We’ve written about the subject of ocean dead zones on a number of occasions—basically that they’re expanding because of human activity, fertilizer run-off, other factors—but new research indicates that we may be writing about them even more. Chalk it up to global warming:
Global Warming-Caused Dead Zones Could Last Thousands of Years
Danish scientists have found that because of unchecked global warming, low-oxygen areas of the ocean could increase 10 times or more. And unlike coastal dead zones caused by human activity, which could recover if the activity that’s causing the dead zone is controlled, the dead zones caused by global warming could remain for thousands of years.
Science Codex summed up the implications of this:
Extreme events of ocean oxygen depletion leading to anoxia are thought to be prime candidates for explaining some of the large extinction events in Earth history including the largest such event at the end of the Permian 250 million years ago.
Furthermore, as suboxic zones expand, essential nutrients are stripped from the ocean by the process of denitrification. This in turn would shift biological production in the lighted surface layers of the ocean toward plankton species that are able to fix free dissolved nitrogen. This would then lead to large, unpredictable changes in ocean ecosystem structure and productivity, on top of other large unpredictable changes to be expected from ocean acidification, the other great oceanic consequence of high atmospheric carbon dioxide concentrations from fossil fuel burning.
via: Science Codex
Ocean Dead Zones
Ocean ‘Dead Zones’ Increasing: 400 Oxygen-Deprived Areas Now Exist
Tropical Dead Zones Set to Expand by 50% Under Climate Change
Corn Ethanol Worsens Gulf of Mexico Dead Zone
A Primer of Global Warming-Caused Marine Dead Zones