Here's yet another alarming consequence of human-driven climate change. We're rapidly smothering the ocean, and the creatures that live in it.
A new study in Global Biogeochemical Cycles, a journal published by the American Geological Union, concludes that a reduction in amount of oxygen dissolved in the world's oceans will be evident across large regions between 2030 and 2040, and already is evident in some places.
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The study was led by scientists from the National Center for Atmospheric Research (NCAR).
"Loss of oxygen in the ocean is one of the serious side effects of a warming atmosphere, and a major threat to marine life," NCAR scientist Matthew Long, lead author of the study, said in a press release.
"Since oxygen concentrations in the ocean naturally vary depending on variations in winds and temperature at the surface, it's been challenging to attribute any deoxygenation to climate change. This new study tells us when we can expect the impact from climate change to overwhelm the natural variability."
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According to the study, which was based upon computer modeling, the decrease in dissolved oxygen already is evident in the southern Indian Ocean and parts of the eastern tropical Pacific and Atlantic basins.
The ocean gets its oxygen supply from the surface, both from the atmosphere and from phytoplankton, which release oxygen into the water. But as an article from Yale's Environment 360 explains, as ocean temperatures warm, surface seawater becomes lighter, due to the influx of freshwater from melting glaciers, icebergs and ice sheets, and from expansion. That means that surface water will be less likely to sink into the deep ocean, which will keep those waters from being oxygenated.
A decrease in dissolved oxygen - which scientists call hypnoxia – can cause vast dead zones in the ocean, which are virtually devoid of marine life.