Well not quite, but I thought that such a title to a blog entry would be catchy. Ergo I have deliberately mislabeled the subject matter of this blog entry. As it it, my central air conditioning went out the other day and I am sitting here writing this entry in a hot residence, next to a constantly blowing fan. The repair person shows up on Monday.
More seriously, the true subject matter of this entry comes from The Marginal Revolution. In that entry, entitled "Move South to live longer", Tyler Cowen points to a potentially important new paper recently published by the National Bureau of Economic Research which discusses the effects of extreme weather events on human mortality (a non-gated version can be found here) and as an accompanying topic discusses the effects of migration towards warmer climes.
This is the abstract of the paper:
We estimate the effect of extreme weather on life expectancy in the US. Using high frequency mortality data, we find that both extreme heat and extreme cold result in immediate increases in mortality. However, the increase in mortality following extreme heat appears entirely driven by temporal displacement, while the increase in mortality following extreme cold is long lasting. The aggregate effect of cold on mortality is quantitatively large. We estimate that the number of annual deaths attributable to cold temperature is 27,940 or 1.3% of total deaths in the US. This effect is even larger in low income areas. Because the U.S. population has been moving from cold Northeastern states to the warmer Southwestern states, our findings have implications for understanding the causes of long-term increases in life expectancy. We calculate that every year, 5,400 deaths are delayed by changes in exposure to cold temperature induced by mobility. These longevity gains associated with long term trends in geographical mobility account for 8%-15% of the total gains in life expectancy experienced by the US population over the past 30 years. Thus mobility is an important but previously overlooked determinant of increased longevity in the United States. We also find that the probability of moving to a state that has fewer days of extreme cold is higher for the age groups that are predicted to benefit more in terms of lower mortality compared to the age groups that are predicted to benefit less.
So there you have it. Speaking a bit frivolously, if you've ever wondered why those elderly snow birds show up down south every winter, there is some real academic evidence that what they are doing is good for them. Sadly, (and arguably as usual) the effects of extreme cold hit the poor the hardest.
More accurately, the authors state in the paper that both extremely hot and cold weather events cause mortality. However, the data which they collected from the 1972-1988 period indicate that there is a substantial difference between mortality which is caused by extremely hot weather events and cold weather events. In heat spells, there is a marked jump in deaths and as expected many of these deaths are of elderly people. However in the weeks afterwards, there is a substantial drop off of mortality rates. In contrast, with cold spells there are spikes in mortality, but there is no offsetting drop off in mortality rates in the weeks or months that follow (emphasis added)! The authors note that the the incidence of deaths from cold spells is greater than those leukemia, liver disease, or homicides, and that there are sizable differences in deaths from cold blasts, with the cities of Minneapolis, Detroit, Cleveland, and Chicago experiencing the highest rates.
Finally:
We calculate that each year 5,400 deaths are delayed by the changing exposure to cold temperature due to mobility. The average number of years of life gained per delayed death is 9.1 years, a sizable increase in life expectancy. As a consequence, the average individual experiences an increase in longevity of 0.02-0.03 years per calendar year as a result of the lower exposure to cold weather. We compare this figure to the annualized increase in longevity experienced in the United States over the past thirty years, which has been 0.25 years per calendar year. Thus, our estimates indicate that 8%-15% of the gains in longevity experienced by the US population over the past three decades are due to the secular movement toward warmer states in the West and the South, away from the colder states in the North. This evidence on mobility-induced changes to cold weather exposure identifies an important but previously overlooked explanation for increased longevity in the United States.
So there you have it. If you live in Chicago, then pack that U-Haul and head on down to Houston! Your life may depend on it.
Wizard
Posted by The Mighty Wizard at August 11, 2007 02:34 PM