Sunspots: Look at the graphs comparing sunspot activity since 1860 with global sea surface temperatures. They look like matching S curves (unlike the graphs comparing temperatures with CO2 output). Harvard astrophysicist Dr. Willie Soon notes that 2008 may have been a cold year because sunspot activity was low. The sun has been quiet in 2009, too. "If this deep solar minimum continues," Dr. Soon explains, "and our planet cools while CO2 levels continue to rise, thinking needs to change. This will be a very telling time and it's very, very useful in terms of science and society in my opinion."