The researches have analyzed the fossilized ocean fauna found on the seafloor off the coast of California dating 3,400 and 16,100 years ago.
Ice melt and ocean dead zone are increasing concern today.
Researchers analyzed more than 5,400 invertebrates fossils like the clams and found that they nearly disappeared when the oxygen level in the ocean was low.
Over a period of less than 100 years the oxygen level in ocean dropped by between 0.5 and 1.5 milliliters per liter.
There was “dramatic changes and reorganizations for seafloor communities” with this minor change.
Climate change could have similar effects and may take similar time to recover in future.
Lead author Sarah Moffitt, a scientist from the Bodega Marine Laboratory and Coastal and Marine Sciences Institute at the University of California, Davis, said, “There’s not a recovery we have to look forward to in my lifetime or my grandchildren’s lifetime.”
He added, “It’s a gritty reality we need to face as scientists and people who care about the natural world and who make decisions about the natural world.”