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Enhanced or Impaired?
Human Health in a CO2-Enriched Warmer World

IV. A Brief History of Human Longevity


The last 150-200 years have seen a significant degree of global warming, as the earth has recovered from the global chill of the Little Ice Age and entered the Modern Warm Period.  Simultaneously, the planet has experienced a rise in its atmospheric CO2 concentration that has taken it to levels not experienced for eons.  What effects have these "twin evils" of the climate-alarmist crowd had on human health, as represented by perhaps the best integrative measure of their myriad possible influences, i.e., human lifespan?

Obviously, no one can give a precise quantitative answer to this question.  Nevertheless, there are ways to assess the relative importance of the wrongly-presumed negative health influences of global warming and atmospheric CO2 enrichment by considering the history of human longevity.

Tuljapurkar et al. (2000), for example, examined mortality over the period 1950-1994 in the G7 countries -- Canada, France, Germany (excluding the former East Germany), Italy, Japan, the United Kingdom, and the United States.  The authors found that "in every country over this period, mortality at each age has declined exponentially at a roughly constant rate."

In discussing these findings, Horiuchi (2000) notes that the average lifespan of early humans was approximately 20 years, but that in the major industrialized countries it is now about 80 years, with the bulk of this increase having come in the past 150 years.  He then notes that "it was widely expected that as life expectancy became very high and approached the 'biological limit of human longevity,' the rapid 'mortality decline' would slow down and eventually level off," but he states the now obvious fact that "such a deceleration has not occurred."

"These findings give rise to two interrelated questions," says Horiuchi: (1) "Why has mortality decline not started to slow down?" and (2) "Will it continue into the future?"

Some points to note in attempting to answer these questions are the following.  First, in Horiuchi's words, "in the second half of the nineteenth century and the first half of the twentieth century, there were large decreases in the number of deaths from infectious and parasitic diseases, and from poor nutrition and disorders associated with pregnancy and childbirth," which led to large reductions in the deaths of infants, children and young adults.  In the second half of the twentieth century, however, "mortality from degenerative diseases, most notably heart diseases and stroke, started to fall," and the reduction was most pronounced among the elderly.  Some suspected that this latter drop in mortality might have been achieved "through postponing the deaths of seriously ill people," he said; but data from the United States demonstrate that "the health of the elderly greatly improved in the 1980s and 1990s, suggesting that the extended length of life in old age is mainly due to better health [our italics] rather than prolonged survival in sickness."

Providing additional support for this conclusion is the study of Manton and Gu (2001).  With the completion of the latest of the five National Long-Term Care Surveys of disability in U.S. citizens over 65 years of age -- which began in 1982 and extended to 1999 at the time of the writing of their paper -- these researchers were able to discern two most interesting trends: (1) disabilities in this age group decreased over the entire period studied, and (2) disabilities decreased at a rate that grew ever larger with the passing of time.

Specifically, over the entire 17-year period of record, there was an amazing relative decline in chronic disability of 25%, as the percentage of the over-65-years-of-age group that was disabled dropped from 26.2% in 1982 to 19.7% in 1999.  What is more, the percentage disability decline rate per year for the periods 1982-1989, 1989-1994 and 1994-1999 was 0.26, 0.38 and 0.56% per year, respectively.  Commenting on the ever-accelerating nature of this disability decline, the authors say "it is surprising, given the low level of disability in 1994, that the rate of improvement accelerated" over the most recent five-year interval.

Finally, Oeppen and Vaupel (2002) report that "world life expectancy more than doubled over the past two centuries, from roughly 25 years to about 65 for men and 70 for women."  What is more, they note that "for 160 years, best-performance life expectancy has steadily increased by a quarter of a year per year [our italics]," and they emphasize that this phenomenal trend "is so extraordinarily linear that it may be the most remarkable regularity of mass endeavor ever observed."  They also report there are no indications of the worldwide life-extension trend leveling off anytime soon.

To summarize to this point, it appears that in countries with highly developed market economies, such as the G7 nations, where good health care is readily available, deaths of infants, children and young adults have been dramatically reduced over the last century or so, to the point where average life expectancy is now largely determined by what happens to elderly people; and it is evident that under these circumstances, the elderly are living longer and longer with the passing of time.  It is further evident that this phenomenon -- which is an observed empirical reality -- is likely due to ever-improving health in older people, which in turn is likely the result of continuing improvements in their bodily systems for repairing cellular damage caused by degenerative processes associated with old age.

What is responsible for this incredible phenomenon?  Nobody knows for sure.  But what we do know for sure is that it has operated unimpeded with unwavering consistency ever since the inception of the Industrial Revolution, concomitant with simultaneous significant increases in both air temperature and atmospheric CO2 concentration.  Hence, we can confidently conclude that the "twin evils" of the climate-alarmist crowd have had not the slightest negative influence on this most welcome development.  In fact, their general coherence in time with the 160-year linear increase in best-performance life expectancy almost leads one to suspect that one or both of them might even be partially responsible for the lengthening lifespan of mankind.