I always like to consider questions of the day from the perspective of deep time. How hot is it these days? Look back 1.35 million years, and you can see it’s pretty hot. Here’s a chart, published yesterday in the Proceedings of the National Academy of Sciences (free paper here). It combines historical records with geological evidence from the West Pacific to reach back 1.35 million years (kyr= thousands of years ago). The scale is telescoped near the right end, since recent warming has been so fast that it would be hard to make out its details otherwise. Two lines mark some average recent temperatures–the lower line is from 1870 to 1900, when recent global warming was just starting