September 02, 2007
Bjorn Lomborg Expects Global Warming To Increase Life Expectancies

In Europe more people are killed by cold weather than by warm weather.

How will heat and cold deaths change over the coming century with global warming? Let us for the moment assume—very unrealistically—that we will not adapt at all to the future heat. Still, the biggest cross-European cold/heat study concludes that for an increase of 3.6 degrees Fahrenheit in the average European temperatures, “our data suggest that any increases in mortality due to increased temperatures would be outweighed by much larger short-term declines in cold-related mortalities.” For Britain, it is estimated a 3.6°F increase will mean 2,000 more heat deaths but 20,000 fewer cold deaths. Likewise, another paper incorporating all studies on this issue and applying them to a broad variety of settings in both developed and developing countries found that “global warming may cause a decrease in mortality rates, especially of cardiovascular diseases.”

Mind you, this benefit of warmer weather might not be found in Africa, the Middle East, the Indian subcontinent, or other already very warm places.

In industrialized countries air conditioning appears to have decreased deaths from heat.

Yet something great happened in the decades following. Death rates in Philadelphia and around the country dropped in general because of better health care. But crucially, temperatures of 100°F today cause almost no excess deaths. However, people still die more because of cold weather. One of the main reasons for the lower heat susceptibility is most likely increased access to air-conditioning. Studies seem to indicate that over time and with sufficient resources, we actually learn to adapt to higher temperatures. Consequently we will experience fewer heat deaths even when temperatures rise.

Indeed humans live longer in warmer weather and cold weather seems to wear us out more quickly if we believe a paper by Olivier Deschenes and Enrico Moretti and published by the National Bureau of Economic Research:, Extreme Weather Events, Mortality and Migration.

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.

Global warming, by decreasing exposure to cold weather, should therefore increase life expectancies of people who now live in colder climates.

I wonder whether the real benefit of a southward migration is reduced exposure to the cold or increased exposure to the rays of the sun. Greater sunlight exposure reduces depression and also increases vitamin D production and therefore reduces incidence of cancer and other diseases. But even if life expectancy benefit comes from more sunlight exposure a warming of northern climes will get people outside sooner in springtime and hence up their vitamin D production.

Cold weather also probably reduces levels of exercise. Plus, in warmer climes locally grown vegetables and fruits are available more of the year. So diets might be better in warmer areas of industrialized countries.

Share |      Randall Parker, 2007 September 02 11:46 PM  Aging Studies

Jason Malloy said at September 4, 2007 12:25 PM:

Global warming could decrease intelligence. The reason could be the spread of biologically harmful insects.

Jason Malloy said at September 4, 2007 12:45 PM:

Life expectancies appear to increase with latitude, so while deaths directly from exposure may increase, life expectancy as a whole may increase with cold weather for a variety of reasons, e.g. less infectious agents. Also people are possibly murdered less since they appear to engage in less violence when it's cold out.

Matias said at September 5, 2007 4:13 AM:

If global warming kicks in to full effect then expect there to be water shortages and wars breaking out all over the place, which is unlikely to be very helpful for global life expectancies.

However man-made global warming may be stopping an ice age from occurring, which would be of huge detriment to life expectancy.

Tj Green said at September 7, 2007 4:50 PM:

The ability to regulate body temperature decreases as we age,for example,more strokes in winter. I like the idea of heated electric blankets,that can be left on all night during cold spells,and places where people can go to cool down during heatwaves. Cold weather is the best insecticide,but there are fabrics/nets that can kill mosquito`s for up to five years.

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