Question: Why do you want to know what the earth was 3 million years ago?

James Pope answered on 26 Jun 2012:

Hey kcsully98

I want to know and understand about the climate of the Earth 3 million years ago, because it was about 3°C warmer than the present day, which is the level or warming expected for us to reach by 2100. We hope that if we can understand this past climate better we can make better predictions of what the climate will be like in 2100.

Because it has happened, there are fossils of microscopic plankton called foramifera, which when the live build a shell out of elements such as magnesium and calcium in the water. We can measure how much of each they have and from this work out the temperature of the water they lived in, which is some really clever chemistry. We can repeat this all over the planet, so that for the time period 3million years ago, we have just over 100 points where we have temperature data. We can also do this with fossil pollen on land to recreate the vegetation.

I can use this data, which was collected together by the US Geological Survey and working with them we can test how our models do against the data points and when we know where they are doing well, we can join the dots as such and recreate the climate.

Hopefully from this we’ll have a better idea of what global warming will do if we get warming of 3°C by 2100.