Icebox or hothouse?

  • Exhibition Text

    • By observing other stars, we think that the Sun’s luminosity has increased by 25 percent since its formation. Thus, the early Earth must have received less sunlight, and should have been covered with ice. While there is evidence of periodic Ice Ages early in the Precambrian, they were not lengthy. One possible reason why the Earth did not become an icebox is that the early atmosphere had a high concentration of greenhouse gases, particularly carbon dioxide. These served as an insulating blanket, keeping the surface warm.

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  • For Educators

    • Topic: Earth Science

      Subtopic: Atmosphere

      Keywords: Solar radiation, Greenhouse gases, Greenhouse effect, Atmospheric, Glacial epoch, Paleoclimatology

      Audience: General

In This Section

The earliest Ice Ages

The earliest Ice Ages

This 2.3-billion-year-old outcrop of the Bruce formation contains evidence of a very early Ice Age.

Debris from old glaciers

Debris from old glaciers

The broken-up rock fragments in this conglomerate from the Gowganda formation are not in contact with one another.