(HealthDay News) — New research suggests that U.S. climate change, and the unpredictable temperature swings it can bring, may be affecting mortality rates in seniors. The findings appear in a research letter published online July 13 in Nature Climate Change.

Liuhua Shi, a graduate student in the department of environmental health at Harvard’s School of Public Health in Boston, and colleagues looked at Medicare statistics regarding 2.7 million people over the age of 65 in New England from 2000–2008. Of those, Shi told HealthDay, 30% died during the study.

The researchers found mortality rates rose when the average summer temperature rose significantly, and rates dropped when the average winter temperature rose significantly.

The researchers believe the increased risk in the summer is due to an increase in the variability of temperatures. According to Shi, “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.” On the other hand, warmer winter temperatures caused by climate change could actually reduce deaths, the researchers added.

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