Droughts in North Africa, overwhelming heat waves in India, terrible air pollution in Paris and other weather-related problems in recent years are often cited as potential evidence of global warming. Large-scale environmental issues, however, could also be viewed as anomalies, but it is less obvious climates changes in the U.S. that a new study connected to higher death rates, particularly among seniors.
While scientist debate the health ramifications of global warming, a discernable impact can already be measured in changing U.S. climates, according to a new study, published in the July 13 issue of Nature Climate Change. In fact, the research shows that temperature swings may already be boosting death rates for senior citizens.
Scientists have long assumed that climate change will make people sicker and kill through extreme heat, more flooding and more polluted air like the situations in India and other spots this year. However, Liuhua Shi, a graduate student in environmental health at Harvard University’s School of Public Health and her peers, studying U.S. Medicare data and death rates, determined that short-term rises in summer temperatures resulted in an increase in death.
The researchers launched their analysis with the intention of better understanding how the weather affects death rates. Earlier studies (and news reports during heat waves) indicated there was an association between short-term changes in temperature and increases in death rates. However, as Shi noted, there had been little evidence gathered on the long-term effect of temperature.
The research team examined Medicare data from 2000 to 2008 on people over the age of 65 in the New England area. Of the 2.7 million New England seniors in the sample, approximately 30 percent died during the study period.
The group then looked at the weather patterns during the time the seniors died. They found that death rates rose during periods when the average summer temperatures increased significantly and were outside the norm. On the flip side, during winters, the Medicare death rates went down in periods when the average winter temperatures were noticeably higher. Both exemplify the impact of warmer than normal temperatures. “Climate change may affect mortality rates by making seasonal weather more unpredictable, creating temperature conditions significantly different to those to which people have become acclimatized,” Shi pointed out.
The Harvard group believes the increased summer risk of death was actually due to more variability in hotter temperatures and people’s inability to adapt. They suggested that it is more difficult for people to develop endurance when the temperature pattern is abnormal than when they are in an area with consistently hot weather (i.e., hot weather in Boston is unusual but weather even hotter in Arizona is normal, so people adapt). Conversely, warmer winter temperatures caused by climate change could actually reduce deaths by avoiding the biting impact of colder, frigid weather.
Before being taken as gospel, it should be noted that the study is geographically limited and has weaknesses. The causes of death are not included, so a bad or mild flu season or other variable is not considered along with weather. Additionally, the experience in New England would have to be compared with data from other areas to see if the results pan out or are misleading.
The research team acknowledges that this study was merely a first step in looking at whether climate changes can be connected to higher death rates in the U.S. and elsewhere. Recognizing that people could respond differently in different climate zones, the group plans to, according to Shi, conduct “a national study to examine the long-term effects of temperature on mortality in each climate zone.”
Written and edited by Dyanne Weiss
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