The Atlantic: "When I asked Simon Lee, an atmospheric scientist at Columbia University, just how unusual this heat is, he explained that the question is, in one sense at least, all but impossible to answer. Compared with the past? Clearly unusual. In the context of our present climate? To establish the baseline we’re measuring against, Lee said, we would ideally rely on years of somewhat consistent observational data. But the climate is simply changing too rapidly. How do you ascertain what is unusual when you can’t even get a grip on what is usual?"