Although there may only be satellite data of sea ice coverage going back 25 yrs, other records with global temperature proxies go back much further. Greenland ice cores go back as far as 123,000 yrs and Vostok goes 400,000 and I think another antarctic core goes back up to 800,000. The global carbonate rock record gives us another temperature proxy reaching back to ~65ma. And how is global warming a scam? The globe, currently, is warming. Global warming. And although this film was clearly not on the conservative side of the climate change debate, I don't agree that it appeared to "think it knows it all." It presented some facts (yes, facts) about warming/albedo and warming/methane release positive feedbacks, but it made no projections of earth's fate and in fact never once iterated that current climate change is anthropogenic in origin.