Past climates: Slower changes

  • Image:

  • Image: Dr Ron Blakey /

  • Image: Hawaii Volcano Observatory (DAS)

  • Image: RyszardStelmachowicz

  • Image: NASA / Dave Pape

  • Image: NASA Goddard Space Flight Center

    Natural processes including changes in solar output, plant evolution, the gradual drift of the continents, slow changes in ocean currents, and long-lasting volcanic eruptions have led to past climate changes over timescales of millions of years. Changes in atmospheric carbon dioxide levels through photosynthesis or chemical weathering have often played an important part.