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Marine Life Survived 8X Current CO2 Levels
Throughout Earth’s history, there is evidence of large carbon dioxide releases, greenhouse conditions, ocean acidification, and major changes in marine life. About 120 million years ago (mya), during the early part of the Cretaceous period, a series of massive volcanic eruptions pumped huge amounts of carbon dioxide into Earth’s atmosphere. During the Aptian Oceanic Anoxic Event, atmospheric CO2 content rose to about twice today’s level. Eventually, the oceans absorbed much of that CO2, which significantly increased the water’s acidity. The change reduced the amount of calcium carbonate (CaCO3) in the water, making it difficult for creatures such as some kinds of plankton to form shells. But the plankton did not die out. In fact, the geological record indicates that ocean biota can adapt to CO2 concentrations as high as 2000 to 3000 ppm—five to eight times current levels.
Read more by Doug L. Hoffman, The Resilient Earth: Marine Life Survived 8X Current CO2 Levels