Climate is a phenomenon that is not always the same.The Climate changes, there was the ice age and then there is the climate now.
But, Can we look into the past and see “How Earth’s climate was in the past?”
Tree Rings, Ice cores, and coral reefs acts as our agents here.
Each year trees add a new layer of growth between the older wood and the bark. Tree ring tells us about the speed of growth and reflects environmental conditions and tree rings usually grow wide during warm periods and narrower during cold period.
Ice cores has inter-glacial contain information about past temperature, and environment. The ice encloses small bubbles of air that contain a sample of the atmosphere including carbon dioxide and methane) in the atmosphere and using this we can predict the climate.
Bleaching on coral reefs give us an idea about the temperatures. Higher the temperature more the bleaching.