Rising solar radiation reflects China's clean air progress: study

BEIJING -- While the sun rises daily, the amount of sunlight reaching the Earth's surface has fluctuated dramatically over the decades. A new study has revealed that China has undergone a dramatic shift from atmospheric "dimming" to "brightening" as a result of its air quality improvements.

The study, led by an international team of scientists from Switzerland and China, was published in the journal Advances in Atmospheric Science on Tuesday. It revealed that periods of "dimming" and "brightening" are closely linked to air pollution levels and the adoption of clean energy solutions.

Air pollution from sustained fossil fuel use can intercept incoming solar radiation, preventing it from reaching the Earth's surface, said Martin Wild, a professor at the Swiss Federal Institute of Technology and lead author of the study.

According to the study, solar radiation levels in China dropped sharply from the 1960s through the 1990s. However, since the 2000s, those levels have rebounded as the country ramped up clean energy initiatives and strengthened emissions controls.

"The causes for these dramatic changes are thought to be primarily due to increasing air pollution in the 'dimming' phase, and due to the successful implementation of air pollution mitigation measures in the 'brightening' phase," Wild said.

"China provides a conducive environment for understanding how air pollutants impact solar radiation," Wild said. "The country's well-organized, long-term monitoring systems make it one of the most studied regions for dimming and brightening effects."

Wang Kaicun, a professor at Peking University, emphasized the importance of continued research and monitoring in this area.

"The solar energy at the Earth's surface is an important renewable energy and its availability is a critical factor for vegetation growth and food production," Wang said, calling for "sustained investment in both investigation and long-term monitoring from the surface and space."