Explosion In Marine Biodiversity Explained By Climate Change
A global change in climate could explain the explosion in marine biodiversity that took place 460 million years ago. Researchers from Lyon (1) and Canberra (Australia) (2) have found evidence of a progressive ocean cooling of about 15°C over a period of 40 million years during the Ordovician (3). Until now, this geologic period had been associated with a "super greenhouse effect" on our planet.
The results from this study were published in the July 25, 2008 issue of the journal Science.
The researchers found that marine water at the beginning of the Ordovician (480 million years ago) was very warm (around 45°C), too warm for complex living organisms to develop. The temperature measurements were obtained from fossils of primitive eels called conodonts, whose geologic age was known by the researchers. They analyzed a mineral found in these eels' skeleton for changes in the ratio of two oxygen isotopes, which is dependent on the temperature of the ocean water in which the animals lived. The early Ordovician was a time when our planet's atmosphere was still very rich in CO2, causing a strong greenhouse effect and therefore very high ocean temperatures...
