Lack of oxygen worsened 'Great Dying'

The biggest of Earth’s mass extinctions may have left animals gasping for air, a new study finds.

The Great Dying, as it is called, occurred some 250 million years ago. Roughly 90 percent of all marine life died, as well as nearly three-quarters of all land plants and animals. It marks the transition from the Permian geological period to the Triassic.

While fossils reveal the extinction in concrete terms, its causes are less well known.Scientists have blamed the massive die-off on an asteroid, volcanoes, global warming, and any combination thereof.

Now Raymond Huey and Peter Ward of the University of Washington have shown that a reduced supply of oxygen could explain high extinction rates that preceded the Great Dying, as well as the very slow recovery that followed.

Currently, oxygen makes up about 21 percent of our atmosphere, but in the early Permian period it was 30 percent. From this invigorating level, it fell to about 16 percent at the time of the Great Dying and over the next 10 million years continued to drop to 12 percent.

"Oxygen dropped from its highest level to its lowest level ever in only 20 million years," Huey said today.

With oxygen only 16 percent of the atmosphere, animals at sea level breathed air similar to that at the top of a 9,200-foot mountain today. At 12 percent, the corresponding elevation would be 17,400 feet. If you've ever climbed such a mountain, you know the effect.

For Subscribers

FOR SUBSCRIBERSCBP leaders cut out of Trump ad buy decision

FOR SUBSCRIBERSAmerican passenger drafted goodbye texts to her family as Flydubai plane plummeted

FOR SUBSCRIBERSCornell rape allegation pushes embattled New York prosecutor into national spotlight

FOR SUBSCRIBERSAbdul El-Sayed tries to woo MAHA voters as Democrats seek inroads with RFK’s supporters

FOR SUBSCRIBERSKratom-like substances are popping up in a typically benign supplement

FOR SUBSCRIBERSGOP super PAC increases its spending for Sen. Jon Husted in tough Ohio race

FOR SUBSCRIBERSRecords reveal tumultuous marriage between slain New York Times executive and wife

FOR SUBSCRIBERSFrom clean energy warrior to ‘wall of shame,’ James Talarico reverses on a fossil fuel money pledge

FOR SUBSCRIBERSCongressional staff planned official trip with luxury stops in Italy and France weeks before election

FOR SUBSCRIBERSA harrowing ordeal aboard an Israel-bound plane

FOR SUBSCRIBERSOpenAI CEO Sam Altman to skip congressional hearing on rogue AI agents

FOR SUBSCRIBERSKey DOJ lawyers departed Trump ‘grand conspiracy’ probe amid pressure to produce, source says

FOR SUBSCRIBERSTrump’s new AI chatbot often links to a site launched under Clinton 26 years ago

FOR SUBSCRIBERSAt MAHA summit, industry CEOs the movement once vilified take the stage

FOR SUBSCRIBERSThis Paralympian has two goals: Win medals and give away $500,000 to her teammates

"Animals that once were able to cross mountain passes quite easily suddenly had their movements severely restricted," Huey said.

For Subscribers

FOR SUBSCRIBERSCBP leaders cut out of Trump ad buy decision

FOR SUBSCRIBERSAmerican passenger drafted goodbye texts to her family as Flydubai plane plummeted

FOR SUBSCRIBERSCornell rape allegation pushes embattled New York prosecutor into national spotlight

FOR SUBSCRIBERSAbdul El-Sayed tries to woo MAHA voters as Democrats seek inroads with RFK’s supporters

FOR SUBSCRIBERSKratom-like substances are popping up in a typically benign supplement

FOR SUBSCRIBERSGOP super PAC increases its spending for Sen. Jon Husted in tough Ohio race

FOR SUBSCRIBERSRecords reveal tumultuous marriage between slain New York Times executive and wife

FOR SUBSCRIBERSFrom clean energy warrior to ‘wall of shame,’ James Talarico reverses on a fossil fuel money pledge

FOR SUBSCRIBERSCongressional staff planned official trip with luxury stops in Italy and France weeks before election

FOR SUBSCRIBERSA harrowing ordeal aboard an Israel-bound plane

FOR SUBSCRIBERSOpenAI CEO Sam Altman to skip congressional hearing on rogue AI agents

FOR SUBSCRIBERSKey DOJ lawyers departed Trump ‘grand conspiracy’ probe amid pressure to produce, source says

FOR SUBSCRIBERSTrump’s new AI chatbot often links to a site launched under Clinton 26 years ago

FOR SUBSCRIBERSAt MAHA summit, industry CEOs the movement once vilified take the stage

FOR SUBSCRIBERSThis Paralympian has two goals: Win medals and give away $500,000 to her teammates

This contradicts the prevailing view of Pangea, the super-continent that existed back then and which later broke apart to form all the modern continents. Most paleontologists considered it a "superhighway" on which species could range freely, Ward said. But with so little oxygen, high elevations would act as barriers.

Secluded populations would be more vulnerable to other environmental challenges, like severe climate change. It would also take longer for isolated organisms to bounce back.

The findings were published in the April 8 edition of the journal Science.