A study conducted by Climate Central, an independent group of scientists and climate specialists based in the United States, has revealed that the number of nights with temperatures exceeding 25 degrees Celsius has significantly increased for approximately one-third of the global population. This rise, attributed to climate change, carries substantial health consequences.
The study compared the annual rate of warm nights between 2014 and 2023 with a hypothetical world free from human-induced climate change. This comparison was based on a peer-reviewed methodology using models that incorporated historical data. However, the data was inconsistent and incomplete in some countries, prompting researchers to create an alternative scenario where the only variable changed was the amount of carbon in the atmosphere.
The study concluded that over the past decade, about 2.4 billion people have experienced at least two additional weeks of nights with temperatures above 25 degrees Celsius compared to a world without climate change. Trinidad and Tobago in the Caribbean recorded the highest average increase, with 47 additional hot nights annually. Similarly, Mumbai, India, endured two extra months of hot nights.
Nick Obradovich, Chief Scientist at the Laureate Institute for Brain Research in the United States, highlighted that increased night-time temperatures, particularly during the hotter periods of the year, can impair sleep and reduce physical recovery following high daytime temperatures, potentially leading to cascading health effects.
Obradovich, who was not involved in the study, noted that the 25-degree Celsius threshold is not an absolute measure. While health generally remains stable below this temperature, it can deteriorate above it, with varying consequences depending on the individual. In some cases, this can lead to life-threatening conditions.
Several studies have shown that night-time temperatures exceeding 25 degrees Celsius degrade sleep quality and duration, which are vital for human functioning. These conditions increase the risk of stroke, cardiovascular disorders, and mortality, especially among the elderly.
Climate change is causing temperatures to rise during both day and night. High night-time temperatures are hazardous as they prevent the human body from cooling down and recovering from daytime heat.
The World Health Organization recommends maintaining room temperatures at or below 24 degrees Celsius at night. Exceeding this limit can make sleep uncomfortable and negatively impact the health of vulnerable individuals, such as children, the elderly, and those with chronic illnesses.
