Early Ice Ages

New research led by scientists from Oxford University and Exeter University has shown that the invasion of the land by plants in the Ordovician Period (488-443 million years ago) cooled the climate and may have triggered a series of ice ages. During this period sea levels are very high and at the end of the period there was a mass extinction event. At the beginning of the period, around 480 million years ago, the climate was very hot due to high levels of CO2, which gave a strong greenhouse effect. The marine waters are assumed to have been around 45°C, which restricted the diversification of complex multi-cellular organisms. But over time, the climate become cooler, and around 460 million years ago, the ocean temperatures became comparable to those of present day equatorial waters. The dramatic cooling of the planet between 300 and 200 million years ago was also the result of the evolution of large plants with large rooting systems that caused huge changes in both of these processes.