Calculating the tipping point in climate change

Twenty million years ago at the start of the Miocene period carbon dioxide levels in the atmosphere were about 400 parts per million, which is virtually where they are today. At that stage sea levels were twenty to forty metres higher than they are today and there was no polar ice. The high emissions twenty million years ago were caused by carbon dioxide form many volcanic eruptions when the earth was younger. Over the next fourteen million years the planet slowly recycled the carbon dioxide injected into the atmosphere by the volcanoes and levels then fell to a range between 180 parts per million and 280 parts per million. As the carbon dioxide levels fell, so did the sea level, and polar ice was formed. The climate changed from colder to warmer very slowly, but it changed slowly enough to allow life on earth to adapt to those changes. Continue reading