Global Temperatures During the Great Dying

About 252 million years ago, more than 90 percent of all marine species and nearly three-quarters of all land species disappeared during what is known as the Permian Extinction, sometimes called the "Great Dying."

Using the Community Climate System Model (CCSM), scientists have created detailed simulations of the Earth's climate during this period of mass-extinction. Pictured above is a computer-simulated snapshot of global temperatures in Celsius during the Permian Extinction.

The model supports the theory that an abrupt and dramatic rise in atmospheric levels of carbon dioxide was responsible for the mass-extinction.

Based on the model, this is what scientists think happened:

Widespread volcanic activity spewed large amounts of carbon dioxide and sulfur into the atmosphere, raising Earth's temperatures in the higher latitudes by roughly 18°F to 54°F (10°C to 30°C).

The warming extended deep into the ocean waters, interfering with the circulation of oxygen and nutrients that naturally occurs when cold, dense water descends into the depths and heated water warmed by ocean vents rises to the surface.

As a result, the ocean waters became stagnant and marine life quickly died off. Without marine life to help remove carbon dioxide from the atmosphere, temperatures on land warmed excessively and oxygen levels plummeted.

From an initial 30 percent during the early Permian period, oxygen levels had dropped to about 16 percent by the time of the Great Dying and soon terrestrial species began dying as well.

The research was detailed in the September issue of the journal Geology.

--Ker Than

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Credit: Courtesy Jeffrey Kiehl, NCAR