Cretaceous Meteor Baked the Dinosaurs

6/23 Global warming, it seems, was a big problem for late- Cretaceous animals like the dinosaurs. A study of rocks at the K-T boundary (the period which marked the extinction of the dinosaurs) shows a significant spike in carbon- dioxide levels. 

Some scientists had previously speculated that evidence for massive volcanic eruptions in India had launched huge amounts of the toxic CO₂ gas into the atmosphere, choking out life on the planet through a subsequent period of global warming. The new study measured CO₂ levels in rocks at the time and presents interesting results.

It now appears the CO₂ increase was both dramatic and immediate- not the relatively slow release expected with a longer- lasting period of volcanic activity. The researchers conclude that the CO₂ spike came from below. Probably the giant meteor that slammed into the earth at the end of the Cretaceous instantly blasted millions of tons of rock into the air, vaporizing the CO₂ they contained.

A slow release of CO₂ gas from volcanoes might have been absorbed by the oceans, but the huge gas release caused by a meteor impact would be too much, too fast, for the natural process of the seas to counteract. Instead, the CO₂ would have saturated the atmosphere and caused as much as a 45° F increase in temperatures. The instability in the Earth's climates would have contributed to the meteor impact's fallout and doomed the dinosaurs. 

The study was conducted by scientists from the United Kingdom and the US and was published in the Proceedings of the National Academy of Sciences [Abstract].

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