Statisticians Explain the Obvious Again

Ahh, the miracle of air conditioning:

According to news reports, the recent heat wave in California resulted in about 150 deaths. The United Nations' Intergovernmental Panel on Climate Change predicts that global warming will exacerbate the problem dramatically, doubling or tripling the number of heat-related fatalities in North American cities in the next decade. The UN is dead wrong, because it assumes what climate researchers call the "Stupid People Hypothesis": that people will simply sit around and fry to death without doing anything to beat the heat.

Global warming or not, our cities are warming, and will continue to do so. Sprawling masonry and blacktop retain heat, and the density of urban construction prevents wind from cooling it off. (Here in D.C., there's an additional warming effect: waste heat from all the money changing hands.)

But heat and heat-related deaths are not synonymous. In fact, in several refereed papers published in recent years, my Virginia colleague Robert Davis and I demonstrated that heat-related deaths have, in aggregate, declined significantly as our cities have warmed. In fact, in a statistical sense, we have completely engineered heat-related mortality out of several of our urban cores, particularly in eastern cities like Philadelphia.

Considering every decade of mortality data at once is misleading; examining it decade-by-decade is more informative. When looked at sequentially, the data reveals a remarkable adaptation: as cities have warmed, the "threshold" temperatures at which mortality begins to increase have also risen -- more than the temperatures of the cities.

An iron law of economics is that people respond rationally to market forces. The folks who brought air conditioning to market did so, as did the folks who purchased it. As more did so, prices dropped, technology improved to maintain the price point, new players entered, prices dropped again, technology improved again, and so on. The result is that almost anyone who wants to live in a cool climate in the summer heat need only lower the thermostat.

Not surprisingly, heat deaths drop accordingly.

Except in socialist republics like France, of course.

Likewise, as public education declined and people became more ignorant, a burgeoning market opened for statisticians to explain the obvious to imbeciles.