When the lights go out: using night-time data to understand disaster impacts

When a disaster happens, one of the first questions decision-makers ask is: how severely are people affected, and where? This is where night-time light data can be surprisingly powerful.

Through the Night-Time Light Remote Sensing for SDGs (NIGHT-LIGHT) initiative, we use changes in night-time light to help assess damage, disruption, and recovery after disasters. The strength of this approach lies in its simplicity: when lights go out, it often signals power loss, infrastructure damage or population displacement.

While night-time light data does not explain everything, it offers a fast, consistent signal that complements other information sources.

During the recent GEO Open House Webinar, I shared several examples of how night-time light analysis is already being used in real operations. After the 2023 Türkiye earthquake, night-time light change maps helped reveal where power outages were most severe and persistent, providing a population-level view of impact.

Similar methods supported International Committee of the Red Cross (ICRC) ground missions in Sudan, where light-based assessments were incorporated into situation reports at headquarters to inform humanitarian planning.

Night-time light data is also valuable beyond immediate response. By combining it with daytime satellite imagery, statistics, and GIS data, we can produce thematic maps and evaluation reports that track recovery, urban development, and access to services over time.

In Africa, for example, we have developed wealth index products derived partly from night-time light patterns, supporting analysis of poverty and inequality across countries.

NIGHT-LIGHT is closely linked to user needs. We continue to work with organisations such as:

Through these partnerships, we ensure our products respond to real operational questions.

Looking ahead, we are also preparing for new satellite constellations, such as Oriental Smart Eyes, which will further enhance coverage and detail.

Our ambition is to move from a pilot initiative toward a more sustained operational role that supports disaster response, SDG monitoring and evidence-based decision-making.

All the materials from the first webinar, including PPTs are available on the GEO Knowledge Hub work package. This blog is based on Xi Li's presentation during the first GEO Open House Webinar as part of series featuring a summary and entires covering GSNL, GWIS, SlopeRiskGPT and Space and Security.