Research led by HKBU predicts that humidity trends will cause widespread heat stress in China

HONG KONG, June 11, 2024 /PRNewswire/ — A study conducted by a Hong Kong-led research team Baptist University (HKBU) has found that there is a trend of increasing humidity in the northern part of the country China which is not observed in the south. This phenomenon will ultimately become a major determinant of extremely hot and humid weather and will lead to widespread heat stress across the eastern half. Chinathe most populated region of the country by the end of this century.

The research results were published in an international academic journal Nature communication.

Humidity determines the difference in thermal stress

In addition to heat, humidity also affects the degree of heat stress a person experiences because it affects our ability to control body temperature through sweating. IN ChinaWhile heat stress is reported in various parts of the country during the summer, relatively humid weather in the south is believed to have resulted in a higher incidence of heat stress with serious health and economic consequences. However, regional trends in humidity levels and their relationship to extremely hot events are not well established.

To assess how humidity affects heat stress in ChinaA research team led by Professor Gao Meng, professor of the Department of Geography at HKBU, analyzed wet bulb temperatures in the northern and southern China recorded over a 40-year period from 1979 to 2018. Wet-the bulb temperature is read using a thermometer covered with a cloth soaked in water and is a measurement of temperature combined with humidity. It is believed to be able to more accurately reflect the effects of heat stress on the human body.

The heat stress difference between north and south is decreasing

The study found that during this period, the average wet-bulb temperature in northern China increased by 0.23°C per decade, much higher than the 0.07°C per decade in southern China. China. During noon China experienced more extreme hot and humid weather in the past, the results showed that the difference in average wet bulb temperatures, and therefore heat stress, between north and south China narrows.

To understand the reason for this regional variation, the research team examined humidity trends recorded over the same period. It was found that the average level of humidity in the north Chinameasured as water vapor pressure, increased by 0.16 hPa per decade during this period, while in the southern China showed a very slight decrease. The results showed a clear distinction in trends in humidity levels between the north and south China.

This is attributed to faster warming in high-latitude regions eastern Asia as a result of global climate change that regulates large-scale features of the atmosphere. As a result, moisture is transported south China from the South China Sea is attenuated, and moisture transport from the Pacific Ocean northwards China is accelerated. In addition to atmospheric processes, reduced humidity in the south China since 1979 can be explained by the urbanization process, which has resulted in less water evaporating from rural landscapes.

Widespread heat stress expected

The research team then applied attribution analysis using climate model simulations and estimated that the projected increase in wet bulb temperatures over part of the northern part of the country China by the end of this century it may be about 2-3°C higher than in the south China. This means further narrowing of the scope of heat stress in the north and south Chinaand by the end of this century the entire eastern part Chinawhere 94 percent China population life, will likely experience widespread and uniformly increased heat stress.

Professor Gao said: “The results of this study serve as a wake-up call for policymakers, researchers and stakeholders to prioritize the development and implementation of climate change adaptation measures. By taking proactive steps now, China can better prepare for the future and protect their population from the adverse effects of heat stress.”

SOURCE Hong Kong Baptist University