Throughout Earth history, climate has varied greatly

Throughout Earth history, climate has varied greatly.For hundreds of millions of years,the planet had no polar ice caps.Without this ice, the sea level was 70 meters higher.At the other extreme, about 700 million years ago,Earth became almost entirely covered in ice during an event known as nowball Earth.So what causes these massive swings in the planet climate?One of the main drivers is atmospheric carbon dioxide,a greenhouse gas that traps heat.