By the early twenty-first century, efforts to forecast the next century or so had come to focus largely on the issue of climate change or global warming. The people making these predictions ranged from skeptics who largely denied the reality of human-induced global warming to those who imagined something close to human extinction within a few decades. Between those extremes, future scenarios vary about precisely how warm the climate will become, what impacts will be associated with various temperature increases, and the extent to which human actions will be able to mitigate or adapt to these changes. Source 23.5, a brief video created in 2013 for a forthcoming United Nations Conference on Climate Change, presents one set of predictions. Titled “Last Hours,” it is presented and narrated by American journalist, radio host, and political commentator Thom Hartmann, a self-described “democratic socialist.”