As world leaders drag their feet on effectively curbing greenhouse gas emissions, many are left wondering how they can best brace for the effects of global warming.
Thermal comfort, also known as human comfort, is dependent upon the environment to supply conditions needed for humans to avoid feeling too hot or cold. Air temperature makes a big difference, but it is not the only factor that affects thermal comfort. Wind speeds, sunlight, and humidity are some other environmental elements that affect human satisfaction.
Humidity reduces the rate of evaporation of sweat from the skin. Sweating is needed to cool the human body, and when its benefits are reduced it causes physical discomfort.
Wind removes heat from the winter air and makes it feel colder. In China, this wind chill is intensified when the wind blows in frigid air from Siberia.
Scientists from The Institute of Atmospheric Physics of the Chinese Academy of Sciences teamed up with other researchers to establish how thermal comfort has changed in China due to global warming. The researchers used the index of effective temperature, which integrates the results of air temperature, humidity, and wind speed. Human perception of the environment was assigned classifications ranging from very cold to very hot. The classifications corresponded with values on the index of effective temperature.
The study found an increase in the effective temperature over recent decades, due in large part to warmer temperatures and decreasing wind speeds. Rising temperatures led to an increase in the days ranked as comfortable, with far more comfortable days recorded per year. These results, however, varied by both season and region. For example, the study showed a decrease in the number of comfortable days in Eastern China.
The research found an average of 255 days classified as cold or very cold, which comes as little surprise considering the highly-elevated regions of China like Tibet. Regardless, a significant decline of 15 fewer cold days were reported in the last decade compared to the 1960s. In correlation, 30 percent more days ranked as hot or very hot were recorded since the 1960’s.
The study gives insight into the changes in thermal comfort over recent decades and also provides a model by which to predict varying degrees of human comfort in the future. Gao Xuejie is an author of the study from the Institute of Atmospheric Physics. Xuejie said his research team will expand upon this study.
“We can expect further and possibly accelerating levels of change in the future under global warming and, as such, our group is currently working on high-resolution regional climate model simulations to build a clearer picture in this regard,” said Xuejie.
By Chrissy Sexton, Earth.com Staff Writer
Source: The Institute of Atmospheric Physics of the Chinese Academy of Sciences