How Do We Know About Earth's Past Climate?
Earth Holds Multiple Types of Evidence About Its Climate History
The modern thermometer was invented in 1654, and global temperature records began in 1880. So how do scientists know so much about Earth’s climate before then?
The Earth holds climate clues dating back more than 3 billion years; they are contained in rock layers, polar ice sheets, lake beds, and more. Researchers at NASA and elsewhere use these records of Earth’s past climate to help them understand our current and future climate.
This study of past climates is called paleoclimatology. A changing climate triggers many different effects, leaving multiple lines of evidence for scientists to follow. For example, the signs of the ice ages are visible in the features that glaciers carved into the landscape. These climate swings also caused changes in plant communities, sea level, and the composition of Earth’s atmosphere.
Evidence of Earth’s past is all around us. All we need to do is read the signals, such as these below.
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