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The History of Temperature Change

Global warming is a hot topic in today's culture, with several predictions by scientists of dramatic weather conditions and changing sea levels. Yet how drastic these changes are in comparison with the history of temperature change requires a closer look at weather patterns from years past.

Peleogene Period
- Palm trees were growing in Siberia and northern Canada during this time.
  
  At the beginning of the Paleogene period, roughly 65 million years ago, the earth's temperature was very hot; on average, 18 to 27 degrees Fahrenheit warmer than it is today, according to studies by the University of California Math Department. Water temperatures also increased, killing many small marine animals about 55 million years ago. The Arctic was around 73 degrees during this time. By the Eocene Epoch, the continents were mostly where they are today, yet there were no permanent polar icecaps on Earth. Starting about 34 million years ago, however, temperatures dropped drastically and glaciers formed at the poles while sea levels dropped.
Neogene Period
- Grasslands were widespread in Africa.
  
  Grasslands became widespread by the start of the Neogene Period, about 24 million years ago. There is also evidence of cooler temperatures. They remained steady until around 1.8 million years ago. Erratic temperature changes brought about ice ages, or "glacial" periods. The latest glacial period began about 70,000 years ago, and reached as far down as the Great Lakes and covered the British Isles.
Today
- Glaciers are found only by the polar ice caps today.
  
  The average temperature of the earth was reached 10,000 years ago as the last glaciers receded to the polar caps, according to research by the University of California Math Department. There have been minor climate events, such as the Younger Dryas, but the climate has remained steady. More recently, the Earth has been the hottest it has been in the last 12,000 years.

Nature