From Electrification to Urban Nighttime Radiance: Using VIIRS Nighttime Lights to Interpret Progress and Trade-Offs Across Sustainable Development Goals 3, 7, and 11

Nighttime light (NTL) remote sensing provides a globally consistent means of observation of human activity after dark, but its sustainability meaning is context dependent. This study analyzes annual VIIRS Day/Night Band nighttime-light radiance for 467 urban centers from 2015 to 2023 using the same 2015 Global Human Settlement Layer urban-center boundary for every year. Holding the spatial footprint constant provides an apples-to-apples longitudinal comparison: changes in Sum VNL represent changes in satellite-observed radiance within the same geographic area rather than changes caused by expanding or redefining the urban boundary. Across the 467 fixed urban areas, total Sum VNL increased from 7.43 million in 2015 to 8.51 million in 2023 (+14.49%); 374 cities increased and 93 decreased. The sample declined by 2.49% from 2019 to 2020 and increased by 5.44% from 2020 to 2021. Regional 2015–2023 changes were +27.96% in Asia, +16.17% in Africa, +14.78% in Oceania, +11.69% in Latin America and the Caribbean, +3.73% in Northern America, and −1.96% in Europe. Mean VNL is reported alongside Sum VNL to distinguish average radiance intensity from total radiance within each fixed urban footprint. The results demonstrate substantial spatial and temporal heterogeneity but do not by themselves prove energy poverty, over-illumination, electricity consumption, or health exposure. NTL is therefore interpreted as a complementary diagnostic variable for SDGs 3, 7, and 11 that requires contextual validation.