NCPA - National Center for Policy Analysis


July 15, 2004

Scientists at the Zurich-based Institute for Astronomy have discovered that the frequency of sunspot activity coincides with global warming and cooling:

  • Between 1645 and 1715, there were few sunspots observed on the Sun's surface, during a period which coincided with cold weather event referred to as the "Little Ice Age."
  • During the past few hundred years, the number of sunspots has slowly increased, coinciding with a warming trend on the Earth.
  • The Sun has been more active in the last 60 years than it has over the past 1,150 years.

Dr. Sami Solanki and researchers have examined the concentrations of beryllium, an isotope, found in ice cores in Greenland. Beryllium is created by cosmic rays, and the rays are modulated by solar wind. Since the solar winds vary over sunspot cycles, scientists can examine the amount of Beryllium in the ice to help determine the presence of Sunspots.

The research indicates that solar activity is influencing global climate change -- although the number of sunspots has remained constant over the past 20 years, even though the climate has gotten warmer.

Source: Dr. David Whitehouse, "Sunspots Reaching 1,000-year High," BBC News, July 7, 2004; and Ilya G. Usoskin, Sami K. Solanki, et. al., "Millennium-Scale Sunspot Number Reconstruction: Evidence for an Unusually Active Sun since the 1940s," Physical Review Letters 91, no. 21, November 21, 2003.

For BBC text

For study abstract:


Browse more articles on Environment Issues