Andrew Douglass

Andrew Ellicott Douglass is an astronomer from Arizona who discovered a correlation between tree rings and the sunspot cycle.

"Douglass tracked this into past centuries by studying beams from old buildings as well as Sequoias and other long-lived trees. Noting that tree rings were thinner in dry years, he reported climate effects from solar variations, particularly in connection with the 17th-century dearth of sunspots that Herschel and others had noticed. Other scientists, however, found good reason to doubt that tree rings could reveal anything beyond random regional variations. The value of tree rings for climate study was not solidly established until the 1960s." [1] (http://www.aip.org/history/climate/solar.htm)