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Increased Minimum Mortality Temperature in France: Data Suggest Humans Are Adapting to Climate Change.

Barrett JR - Environ. Health Perspect. (2015)

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Outdoor temperatures can influence population mortality rates, with the mortality–temperature relationship typically depicted as a U- or J-shaped curve... The lowest point of this curve defines the minimum mortality temperature (MMT)—that is, the temperature with the lowest mortality rate—while the raised ends represent increased deaths at both lower and higher temperatures... Climate change models predict higher average temperatures and more frequent and intense heat waves in the coming decades... Higher rates of heat-related deaths tend to occur with heat waves earlier in the summer, before people have acclimatized to the season’s hotter temperatures... The researchers used high-resolution climate data to superimpose a grid of 30×30-km squares over continental France... The resultant 295 squares encompassed 36,000 communes, the smallest administrative unit for which sociodemographic data were available... The researchers obtained death certificates for all people aged 65 and older who died of natural causes within continental France during 1968–2009, a total of 16,487,668 deaths. “Temperature influences many causes of deaths,” explains coauthor Alain-Jacques Valleron, emeritus professor at Université Pierre et Marie Curie. “We would have lost much of what we wanted to study—the impact of temperature on mortality—if we had only focused on deaths that were registered as directly related to temperature. ” Analyses of the temperature–mortality relationship focused on grid squares with more than 22,500 deaths during the entire 42-year period (228 squares)... Nearly all squares had U- or J-shaped temperature–mortality curves... The MMT was found to shift upward over time, from 17.5°C (63.5°F) in the first period, to 17.8°C (64.0°F) in the second period, to 18.2°C (64.8°F) in the third period... Mean summer and winter temperatures also increased over time, by 1.6°C (2.9°F) for summer and 0.8°C (1.4°F) for winter... Subsequent sensitivity analyses corroborated these results... The authors concluded that adaptation to higher temperature had occurred during the 42-year period of the study. “I was interested in their conclusions about the MMT shift in time,” says Matthew Heaton, an assistant professor of statistics at Brigham Young University who was not involved in the study. “I think it’s a nice conclusion, but I’d like to see more to justify their conclusions—for example, confidence intervals or hypothesis testing. ” Heaton also praises the length of time covered by the study, “the longest that I’ve seen,” and the fact that it covers rural areas... He points out that some of the analyses focused on locations that had more than 15,000 deaths, which cuts out the least populated areas... However, those analyses did not change the overall conclusions.

No MeSH data available.


As mean summer temperatures in France increased over time (right), so did the temperatures associated with the lowest mortality rates (left).Source: Todd and Valleron (2015)1
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f1: As mean summer temperatures in France increased over time (right), so did the temperatures associated with the lowest mortality rates (left).Source: Todd and Valleron (2015)1


Increased Minimum Mortality Temperature in France: Data Suggest Humans Are Adapting to Climate Change.

Barrett JR - Environ. Health Perspect. (2015)

As mean summer temperatures in France increased over time (right), so did the temperatures associated with the lowest mortality rates (left).Source: Todd and Valleron (2015)1
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492254&req=5

f1: As mean summer temperatures in France increased over time (right), so did the temperatures associated with the lowest mortality rates (left).Source: Todd and Valleron (2015)1

View Article: PubMed Central - PubMed

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

Outdoor temperatures can influence population mortality rates, with the mortality–temperature relationship typically depicted as a U- or J-shaped curve... The lowest point of this curve defines the minimum mortality temperature (MMT)—that is, the temperature with the lowest mortality rate—while the raised ends represent increased deaths at both lower and higher temperatures... Climate change models predict higher average temperatures and more frequent and intense heat waves in the coming decades... Higher rates of heat-related deaths tend to occur with heat waves earlier in the summer, before people have acclimatized to the season’s hotter temperatures... The researchers used high-resolution climate data to superimpose a grid of 30×30-km squares over continental France... The resultant 295 squares encompassed 36,000 communes, the smallest administrative unit for which sociodemographic data were available... The researchers obtained death certificates for all people aged 65 and older who died of natural causes within continental France during 1968–2009, a total of 16,487,668 deaths. “Temperature influences many causes of deaths,” explains coauthor Alain-Jacques Valleron, emeritus professor at Université Pierre et Marie Curie. “We would have lost much of what we wanted to study—the impact of temperature on mortality—if we had only focused on deaths that were registered as directly related to temperature. ” Analyses of the temperature–mortality relationship focused on grid squares with more than 22,500 deaths during the entire 42-year period (228 squares)... Nearly all squares had U- or J-shaped temperature–mortality curves... The MMT was found to shift upward over time, from 17.5°C (63.5°F) in the first period, to 17.8°C (64.0°F) in the second period, to 18.2°C (64.8°F) in the third period... Mean summer and winter temperatures also increased over time, by 1.6°C (2.9°F) for summer and 0.8°C (1.4°F) for winter... Subsequent sensitivity analyses corroborated these results... The authors concluded that adaptation to higher temperature had occurred during the 42-year period of the study. “I was interested in their conclusions about the MMT shift in time,” says Matthew Heaton, an assistant professor of statistics at Brigham Young University who was not involved in the study. “I think it’s a nice conclusion, but I’d like to see more to justify their conclusions—for example, confidence intervals or hypothesis testing. ” Heaton also praises the length of time covered by the study, “the longest that I’ve seen,” and the fact that it covers rural areas... He points out that some of the analyses focused on locations that had more than 15,000 deaths, which cuts out the least populated areas... However, those analyses did not change the overall conclusions.

No MeSH data available.