Climate change is in the news a lot today. There seems to be little doubt that it’s getting warmer and that, should present trends continue, the warming trend will have "historical" consequences. Things are going to change.
Ever thus. As John L. Brooke shows in his remarkable Climate Change and the Course of Global History: A Rough Journey (Cambridge University Press, 2014), what we might colloquially call "the weather" has been nudging, pushing, and dramatically altering the course of World history for eons. Sometimes it’s dry; sometimes it’s wet. Sometimes it’s hot; sometimes it’s cold. Sometimes the air is good; sometimes it’s bad. There are patterns, as John points out, but there’s also a good degree of unpredictability–it is, after all, the weather. What’s happening right now, though, is not in the slightest unpredictable: if we keep dumping greenhouse gases into the atmosphere, it’s going to get hot; if it gets hot, things are going to change–again.