What I'd like to know is how NASA and NOAA, founded in 1958 and 1970 respectively, can cite with any accuracy the specific global climate conditions as far back as 1880, as referenced in Greg's linked article. That's one of the main reasons for skepticism on my part - hypothetical points of reference for their measurements. Another is, as I have already alluded to, the fact that Earth has experienced a number of ice ages, each with a significant warming period between them, and it all happened without humanity dumping carbon dioxide into the air. How do we know that the cycle of ice ages has stopped? It's only been somewhere between 11 & 12 thousand years since the last one, and they are estimated to have begun as long as 2 1/2 million years ago. Why do people automatically assume that another one isn't coming in the future - that any warming trend occurring now isn't just another in a series of climatic cycles?