Long Ago Climates
The climate has been changing for billions of years! It warmed and cooled
many times long before humans were on the planet to influence it.
How do we know what the climate was like a thousand years ago, a million
years ago, or even a billion years ago? That’s long before there
were people keeping track of the weather!
To figure out what climates used to be like, scientists work like detectives
and look for clues around the planet to solve the mystery. These scientists
are called paleoclimatologists. They find clues in the sediments at the
bottoms of lakes and oceans, in the ice of glaciers, in fossils, and inside
trees and corals.
- Thin layers of mud and sand that form in lakes are clues to past climates.
- Fossils of tiny plankton that once floated through the seas contain
clues to ancient ocean temperatures.
- Bubbles trapped inside the ice of old glaciers hold air from many
thousands of years ago.
- Tree rings show what climate was like for each year of a tree’s
life.
- The skeletons of corals contain clues to changing ocean temperatures.
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