Hundreds of millions of years ago, massive ice caps blanketed Earth’s
continents from coast to coast. More recently, lush mega-forests of swamp
cypress and dawn redwood have occupied what is now the Arctic circle.
These dramatic shifts in Earth’s climate have long fascinated geoscientists.
What caused these dramatic transitions between Icehouse and Greenhouse
Earths? How did these different climate states influence the evolution of
life on Earth? Could life itself have altered Earth’s climate?
Ultimately, periods when the Earth was fundamentally different from
today have provided key insights into the Earth’s carbon cycle, or the
planetary machinery that moderates climate over geologic time. Based on
what we currently know about the history of Earth’s carbon cycle, Earth has
never seen a geologic agent quite as rapid and relentless as humans.
