Understanding Global Dimming

  • By Susan K. Lewis
  • Posted 04.18.06
  • NOVA

Like enormous clouds of volcanic ash, some forms of air pollution can significantly reduce the amount of sunlight reaching Earth's surface and lower temperatures. Climate researcher James Hansen estimates that "global dimming" is cooling our planet by more than a degree Celsius (1.8°F) and fears that as we curb these types of air pollution, global warming may escalate to a point of no return. Here, trace the historic events that lead to our understanding of global dimming.

Launch Interactive Printable Version

What is "global dimming" and how can it counter global warming? See how this critical phenomenon was discovered.

This feature originally appeared on the site for the NOVA program Dimming the Sun.

Thanks to Spencer Weart of the American Institute of Physics, whose book The Discovery of Global Warming made this feature possible. A hypertext version of the book can be found at www.aip.org/history/climate/



© Yann Arthus-Bertrand/CORBIS
(mushroom cloud)
(cloud seeding)
Courtesy National Archives of Australia
(Hollywood sign)
Public domain/Courtesy pdphoto.org
(ice coring)
© Greenpeace/Morgan
(surface air temperature increase)
Courtesy NASA
(asteroid impact)
Courtesy NASA/Don Davis
(shipping lane clouds)
Courtesy Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC
(Mount Pinatubo eruption)
Courtesy USGS
(aerosol haze over South Asia)
Courtesy Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC
(Aqua satellite launch)
Courtesy Reto Stí¶ckli, NASA Earth Observatory

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