Late in the last century scientists published reams of data about Earth’s climate derived from ice cores taken from Greenland and Antarctic glaciers. By drilling down into the ice with hollow bits (think of using a spinning pipe as a drill) workers were able to pull columns of ice up to the surface.
Nothing about Earth history is static or unchanging. That’s particularly true of climate, and thereon hangs more than one interesting tale including recent news of a scientific advance in understanding how past climate has changed.