New satellite data has shown that artificial lighting continues to brighten the Earth at night, though the trend varies significantly by region.
While areas such as sub-Saharan Africa and Southeast Asia are becoming more illuminated, parts of Europe are intentionally reducing light levels due to energy-saving measures and concerns over light pollution.
The findings indicate a 16 percent overall rise in global nighttime brightness between 2014 and 2022. However, researchers noted that this increase has not been uniform, describing it instead as a mix of growing and declining light levels shaped by different regional influences. In 2022, the United States recorded the highest total brightness globally, followed by China, India, Canada and Brazil.
Researchers attributed increasing brightness largely to urban growth, expanding infrastructure and improved access to electricity in developing regions.
In contrast, declining light levels were linked to two distinct causes. Sudden drops were often associated with disasters, power outages or conflicts, while gradual reductions were typically the result of policy decisions, energy-efficient lighting adoption and efforts to limit light pollution.
“For decades, we’ve held a simplified view that the Earth at night is just getting steadily brighter as human population and economies grow,” said Zhe Zhu, a professor of remote sensing and director of the Global Environmental Remote Sensing Laboratory at the University of Connecticut, and senior author of the study published Wednesday in the journal Nature.
“We discovered that the Earth’s nightscape is actually highly volatile,” Zhu said. “The planet’s lighting footprint is constantly expanding, contracting and shifting.” The team analysed more than one million daily satellite images captured by a U.S. government Earth-observation satellite and processed by NASA, offering a more detailed perspective than earlier studies that relied on monthly or yearly composites.
The most notable increases in brightness were recorded in developing economies, particularly across sub-Saharan Africa and Southeast Asia. Countries such as Somalia, Burundi and Cambodia led the surge, alongside others including Ghana, Guinea and Rwanda.
“This isn’t just urbanization. It is a massive expansion of energy access,” Zhu said. “These numbers represent a profound shift as entire regions transition from near-total darkness to becoming part of the global electric network.”
Significant declines in lighting were observed in conflict-affected nations such as Lebanon, Ukraine, Yemen and Afghanistan, where infrastructure damage and instability disrupted power supply. Similar patterns were noted in Haiti and Venezuela, largely due to prolonged economic challenges and unreliable electricity systems.
“In Ukraine, we observed a sharp, sustained decrease in light that aligned perfectly with the escalation of the conflict in February 2022,” when Russia launched a large-scale invasion, Zhu said.
“We see similar abrupt darkness falling over regions in the Middle East during periods of conflict,” Zhu said.
Europe recorded an overall 4 percent reduction in nighttime brightness, driven mainly by policy and technological changes.
“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,” Zhu said. “Europe is fascinating because it presents a very structured dimming pattern.” He highlighted France as a global leader in efforts to conserve dark skies and improve energy efficiency.
Co-author Christopher Kyba of Ruhr University Bochum noted: “The dimming in France that took place because of deliberate decisions to turn streetlights off late at night when there is no longer any activity on the streets is extraordinary.
It will be very interesting to see how this develops over time, and whether this practice expands beyond France.”
During the study period, the United States saw a 6 percent increase in light output.
“Geographically, the USA offers a microcosm of this global light complexity. The West Coast largely brightened, consistent with population growth and vibrant tech economies. However, much of the East Coast and Midwest actually dimmed. This was driven by de-densification in older urban cores, the decline of certain manufacturing sectors, and aggressive adoption of smart, energy-efficient city lighting programs like those in Washington and Chicago,” Zhu said.
Artificial illumination has evolved significantly since the introduction of gas lighting in cities during the early 19th century, followed by widespread use of electric lighting later in that century. Today, urban areas glow brightly at night, often obscuring the stars once visible in the sky.
“Light pollution has profound ecological consequences, disrupting nocturnal ecosystems, animal migrations and human circadian rhythms,” Zhu said.
A satellite-generated nighttime image of Earth, compiled from daily observations over the past decade and released on April 8, 2026, illustrates global human activity through artificial lighting. In the image, areas marked in gold indicate increased brightness, purple highlights regions experiencing dimming, and white shows areas with mixed changes.
