Observation data analysis shows that global nighttime artificial brightness has increased by 16% in 8 years

According to the latest issue of Nature magazine, an international research team found through analysis of satellite observation data that the overall brightness of artificial light at night worldwide increased by 16% between 2014 and 2022. However, this trend is not universal. Some regions affected by wars and natural disasters, as well as countries implementing effective energy-saving and light pollution control policies, are actually showing a trend of "dimming".

Continuously increasing artificial light can bring a series of problems, including affecting human sleep, disrupting the biological rhythms of animals and plants, exacerbating light pollution, and weakening the visibility of the starry sky. But research shows that global nighttime brightness changes are not uniformly increasing, but rather forming a "jigsaw puzzle" pattern of fluctuations in different regions. In 2022, the total nighttime brightness of the United States ranked first in the world, followed by China, India, Canada, and Brazil.

From the perspective of driving factors, the increase in brightness mainly comes from accelerated urbanization, infrastructure expansion, and rural electrification, with the most significant growth in sub Saharan Africa and Southeast Asia. The decrease in brightness can be divided into two categories: sudden dimming is often caused by natural disasters, power grid failures, and armed conflicts; Gradual dimming is often related to energy-saving policies and measures to reduce light pollution, as seen in some parts of Europe.

The research team used imaging products from NASA's "Black Marble" night light remote sensing system. This system is based on the observation data obtained by the visible light infrared imaging radiometer group, and uses algorithms to eliminate interference factors such as moonlight, auroras, and cloud cover. Compared with previous studies that relied on annual or monthly composite data, this method can more accurately reflect changes in surface nighttime light sources.

However, current satellite sensors are not sensitive enough to the blue light band, and modern lighting widely uses white LED lights, which emit high levels of blue light. This means that the actual brightness increase in some areas may not have been fully captured.

Previous studies have shown that over the past decade, the brightness of the night sky in human settlements has been increasing at a rate of nearly 10% per year. This continuously increasing nighttime illumination is "erasing" the starry sky, having profound impacts on astronomical observations, human health, and ecosystems.