How do we know what Earth’s climate was like long ago?
Earth’s climate affects almost everything. And so when the climate changes, it leaves traces almost everywhere.
Some of those traces can be seen in the landscape — erratic rocks that have been pushed far from their origin by ancient glaciers, or relic beaches that tell us how high sea level was in the past.
Other traces are more subtle — the composition of ice in cores drilled in Greenland and Antarctica, or the geochemistry of the shells of single-celled organisms in ocean sediment that can date back hundreds of millions of years.
These efforts have led to detailed understanding of the ice ages of th
e last few million years and the hothouse climates of 50 or 100 million years ago.
They’ve given us insight into long-term changes driven by plate tectonics, shorter-term variability driven by the wobbles in the Earth’s orbit, and rapid events such as the climate response to the asteroid impact that killed the dinosaurs.
And they’ve allowed us to see that what’s happening to climate right now is unlike anything else we’ve seen.
So how do we know what Earth’s climate was like long ago? The answers are all around us if we know where to look. Learn more: https://go.nasa.gov/3NihKpm
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