National Geographic : 1967 Feb
The warming of the 1920's, '30's, and '40's, however, proved a boon to the high-level gla ciers. Temperatures here rose during the snow iest months to around 32° F. The heaviest snowfalls occur near the freezing point, so these glaciers became exceedingly healthy. Sunspots Linked to Glacier's Health Glaciers thus periodically experience in creases and decreases of net accumulation, and so they advance, linger, and retreat as precipitation and temperature trends change. The question is: What causes these cycles? Evidence developed by Dr. Hurd C. Wil lett, Professor of Meteorology at Massachu setts Institute of Technology, suggests the 214 answer. Dr. Willett, one of our staff affiliates this year, has shown us how cyclic changes in the climate closely parallel the cyclic changes in sunspot activity-the manifestations of powerful electrical energy discharges from the sun.* We now feel confident that our investiga tions here back up the solar-climate theory of weather cycles. Sunspots have been diligently recorded for well over 200 years. We find that glacier fluctuations over these past two cen turies show a tantalizing correlation, taking into account the glaciers' flow lag, with sun storms and temperature trends. *Dr. Herbert Friedman wrote a fascinating biography of "The Sun" for the November, 1965, GEOGRAPHIC.