Imperiling fish, crabs, squid, sea stars, and myriad other marine creatures, climate change is sapping the oceans of oxygen, according to a new study that warns of widespread deoxygenation within decades.
Using models and maps, researchers at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, were able to quantify and differentiate between large-scale changes in oxygen in the oceans due to both natural variability and climate change.
They confirmed deoxygenated "dead zones"—which leave marine creatures struggling to breathe—caused by climate change already exist in the southern Indian Ocean and parts of the eastern tropical Pacific and Atlantic basins, and determined that more widespread detection of deoxygenation caused by climate change would be possible between 2030 and 2040.
The findings were funded by the National Science Foundation and published in the American Geophysical Union journal Global Biogeochemical Cycles.
"Loss of oxygen in the oceans is one of the serious side effects of a warming atmosphere, and a major threat to marine life," said NCAR scientist Matthew Long, lead author of the study. "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 effect from climate change to overwhelm the natural variability."
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Putting the study in context, Popular Science wrote:
Low levels of oxygen in the oceans can be devastating. Not only can they kill or slow down ocean life in the present, but if low oxygen levels persist, they can have grave impacts on the future. 'The Great Dying' is an extinction event that killed roughly 90 percent of species on Earth 250 million years ago. Researchers looking at the event found that low levels of oxygen in the oceans probably slowed down the recovery of life on Earth. After that extinction, it took five million years for the diversity of life to recover as oxygen levels in the oceans slowly rose back to normal.
On Twitter, United Nations climate chief Christiana Figueres said the findings represented the "Alarm bells...of science ringing loud & clear."
Climate change threatens the world's oceanic ecosystems on several fronts. Just last week, Common Dreams reported that climate change is the underlying cause of the coral bleaching event that has all but destroyed the Great Barrier Reef.
And as the Sydney Morning Herald wrote on Thursday, "We also know that our oceans have become about 30 percent more acidic since pre-industrial times as they absorb the billions of tonnes a year of carbon dioxide released from our burning of fossil fuels and forests, making it harder for shellfish and crabs to form shells."
"We're driving pretty massive changes in the environment—and we're not just changing one variable," Long told the paper. "We're changing a suite of variables to which marine organisms are sensitive, and basically putting significant demands on their adaptive capacities."