According to a research report published in journal Nature Climate Change on Monday, it is not just the heat waves, but temperature swings which can also accelerate death rates in the United States.
The study involved just about 3 million people who were 65 years or older.
A rise of 1 degree C in the summer temperature translated to 1% higher death rate while increased mean temperature during winter contributed to 0.6 % decreased mortality – says Joel Schwartz who is a professor of environmental health at Harvard Chan School of Public Health along with his colleagues.
Summers are getting warmer and scientists have discovered that that more people died in New England while the death rate climbed down with winters that were warmer than usual. However, warmer winter did not compensate warmer summers.
Schwartz adds that everyone who was on Medicare in the New England area was followed and studied the annual death rate along with the average temperature during summer and winter. The team also analyzed the dates of death in relation to an independent database of temperature recording for each day by the zip codes between the period 2000 and 2008. The temperature data was further analysed to determine how variations impacted the death rate in each zip code for the period that was studied.
Researchers concluded from this study that death rates increased when summer temperatures were above the average and similarly there was small drop in death rate when winter temperatures were warmer compared to the average. This study is an addition to the growing array of evidence that some changes influenced by the gradual warming of climate have real time impact on people.
Further, the researchers observed that it was not just the steady fall or rise in temperature that impacted death rates, but the variations that take the temperature outside the average range.
Schwartz went on to add that variability mattered because we do not acclimatize to temperature changes fast enough. When the variability becomes higher on a daily basis during the season, it accounted for more deaths. The finding also finds agreement with other studies which show for example that those who exercise exclusively in the heat get accustomed to that and eventually can push themselves towards more time in the heat. But, when they take an occasional break from the heat they do not get acclimatized soon enough.