How do we know what the climate was like in the past?

In order to find out, scientists use many different methods. One is to dig down through the snow and ice of Antarctica and examine the different layers that have formed over thousands of years. With these ancient blocks of ice we can discover a lot of information about what the temperatures were year after year.

Other methods include looking at ancient coral reefs, rings in tree trunks, stalagmites, old pollen, seeds and leaves. All this data helps paint a picture of what the atmosphere and climate were like throughout history.