Global Cooling increased biodiversity
A new hypothesis for the Cambrian explosion

An explosion in the biodiversity on Earth occurred with the start of the Cambrian era 542 million years ago. The so-called Cambrian explosion is one of the most marked development phases in Earth's history. Scientists at the Potsdam Institute for Climate Impact Research have now proposed a new hypothesis for the cause of this abrupt biological change. Their study is published in the latest issue of Geophysical Research Letters.

According to Werner von Bloh, Christine Bounama and Siegfried Franck at the Potsdam Institute for Climate Impact Research (PIK), a gradual cooling of the climate at the beginning of the Cambrian triggered this boost in biodiversity. The global surface temperature at that time reached the critical value for the onset of complex multicellular life. This multicellular life was able to actively change the environmental conditions to maintain its own existence. This positive feedback reinforced an abrupt change in the biological world: a change from predominantly primitive to multicellular life. Almost all modern animal lines emerged at this time, with Trilobites being the most well-known fossils of this epoch.

The researchers used an Earth-system model developed at PIK for simulations of the coevolution of the geosphere and biosphere. They regarded the gradual cooling as the trigger of the Cambrian explosion and examined the stability of the Earth system with respect to a sudden decline of the global surface temperature before the Cambrian era. They found that a small temperature reduction at the end of the Precambrian could have initiated an earlier onset of the Cambrian explosion. Such cooling events could have been caused by perturbations, for example by the breakup of a supercontinent or the impact of an asteroid or comet. A final answer to the question of why the Cambrian explosion occurred 542 million years ago, cannot yet be given. The new hypothesis, however, will contribute to a deeper understanding of the complex processes interacting in the Earth system.

The Potsdam Institute for Climate Impact Research (PIK) was founded in 1992 and employs 121 scientists. Its research on climate change, climate impacts and sustainable development is of international renown. PIK is a member of the Leibniz Association.

Contact:
Dr. Werner von Bloh, werner.von.bloh@pik-potsdam.de, Tel. +49/331/288-2603
Christine Bounama, christine.bounama@pik-potsdam.de, Tel. +49/331/288-2659
Prof. Dr. Siegfried Franck, siegfried.franck@pik-potsdam.de, Tel. +49/331/288-2659

Press office:
Anja Wirsing, anja.wirsing@pik-potsdam.de, Tel. +49/331/288-2507

Original article:
Werner von Bloh, Christine Bounama, Siegfried Franck. Cambrian explosion triggered by geosphere-biosphere feedbacks. Geophysical Research Letters, doi: 10.1029/2003GL017928, 2003.

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