Note the high degree of correlation of the two search terms.
By the way, if you want to know a little secret I discovered about Ice Rocket; you can manually manipulate the "days=" section of the URL generated after a search-terms graph has been created to look at any number of days up to 270. Don't abuse it if it slows their servers down. I pick low traffic times.
Tags: global+warming, climate+change, graph, blogging, blogs