Satellite data shows Earth is getting ever brighter at night
Daily satellite observations have revealed a continued nighttime brightening globally due to artificial lighting, with important regional variations including a surge in sub-Saharan Africa and Southeast Asia alongside a deliberate dimming in Europe driven by concerns over energy conservation and light pollution.
Researchers documented a 16% net increase in global nighttime light from 2014 to 2022, but showed it was not a steady brightening but rather a patchwork of increasing and decreasing regional brightness shaped by numerous factors. The United States in 2022 had by far the highest total luminosity of any country, followed by China, India, Canada and Brazil.
Brightening was found to be propelled mainly by rapid urbanization, infrastructure expansion and rural electrification.
Dimming, however, had two very different drivers. Abrupt dimming was usually caused by natural disasters, power grid failures and armed conflicts. Gradual dimming was often deliberate, guided by government regulations, transitions to energy-efficient LED lights and efforts to cut light pollution.
The researchers used more than a million daily images obtained by a U.S. government Earth-observation satellite and processed by NASA. Previous global studies relied mostly on annual or monthly composite satellite images.
The most dramatic brightening occurred in emerging economies, particularly in sub-Saharan Africa and Southeast Asia. It was led by Somalia, Burundi and Cambodia, followed by several African nations including Ghana, Guinea and Rwanda.
Meanwhile, Europe experienced a 4% net decrease in nighttime light radiance, largely due to technological advances and environmental policies.
It is driven by a widespread shift from older, less-efficient streetlights like high-pressure sodium lamps to newer, directional LED systems, as well as strict national energy-efficiency mandates and dark-sky conservation efforts. Europe is fascinating because it presents a very structured dimming pattern.
Source: Reuters
