Beijing: According to a modeling study published in The Planetary Health of the Lancet log.
Researchers from the University of North Carolina in the United States have noted that ambient heat during the night can disrupt normal sleep physiology.
Less sleep can then lead to damage to the immune system and a higher risk of cardiovascular disease, chronic disease, inflammation and mental health problems, they said.
The study found that the average intensity of hot night events will almost double by 2090, from 20.4 degrees Celsius to 39.7 degrees Celsius in 28 cities in East Asia, increasing the burden of illness due to excessive heat that disrupts normal sleep.
The results show that the burden of mortality could be considerably higher than that estimated by the increase in mean daily temperature.
The results suggest that warming due to climate change could have a worrying impact, even under the restrictions of the Paris Climate Agreement which aims to limit global warming to well below 2 degrees Celsius, compared to pre-industrial levels.
“The risks of overnight temperature increases have often been overlooked,” said study co-author Yuqiang Zhang, a climatologist at the University of North Carolina.
“However, in our study, we found that occurrences of overnight hot excesses (HNE) are expected to occur faster than average daily temperature changes,” Zhang said.
The study shows that the frequency and the average intensity of hot nights would increase by more than 30% and 60% respectively by the year 2100, against less than 20% increase for the average daily temperature.
The researchers estimated mortality from excessive heat in 28 cities in China, South Korea and Japan between 1980 and 2015 and applied it to two climate change modeling scenarios aligned with the adapted carbon reduction scenarios by the respective national governments.
The team was able to estimate that between 2016 and 2100, the risk of death from excessively hot nights would increase almost six times. This prediction is much higher than the mortality risk from average daily warming suggested by climate change models.
“Based on our study, we emphasize that in assessing the burden of disease due to suboptimal temperature, governments and local decision-makers should consider the additional health impacts of disproportionate intraday temperature variations,” said Haidong Kan, a professor at Fudan University of China.
“A more comprehensive assessment of health risks from future climate change can help policymakers better allocate resources and set priorities,” said Kan, the study’s corresponding author.
The researchers also found that regional temperature differences explained many of the nighttime temperature discrepancies, and that areas with the lowest average temperature would have the greatest warming potential.
“To combat the health risk raised by temperature rise due to climate change, we need to devise effective ways to help people adapt,” Zhang said.
“Locally, heat during the night should be taken into account when designing the future heat wave warning system, especially for vulnerable populations and low-income communities who may not be able to afford the additional air conditioning expenses,” the scientist said.
The researchers said stronger mitigation strategies, including global collaborations, should be considered to reduce future warming impacts.