Satellite imagery used to map global poverty

Despite notable successes in reducing poverty worldwide over the past two decades, almost one billion people still live without access to affordable and reliable electricity, which negatively impacts their health and welfare, and impedes sustainable development. Knowing the precise location of these people is crucial in order to provide them the assistance and infrastructure they need. A recent study led the International Institute for Applied Systems Analysis (IIASA) has proposed a new method to estimate global economic well-being by using nighttime satellite imagery. 

For almost three decades, scientists have used such images – known as “nighttime radiance” or “nighttime lights” – to study human activity and map issues related to economic growth, poverty, or inequality, particularly in places where such data was lacking. While brightly lit areas indicate more developed regions such as capital cities, areas that are unlit at night usually indicate limited development. By contrast to previous studies that assessed data gathered from lit areas, this new study has specifically focused on unlit areas in order to estimate global economic well-being.

“Whereas previous work has focused more on the relationship between lit areas and economic development, we found that it actually also works the other way around and that unlit areas are a good indicator of poverty. By identifying those unlit areas, we can target interventions for poverty alleviation and places to focus on to improve energy access,” explained study senior author Steffen Fritz, the IISSA Strategic Initiatives Program Director.

By combining a harmonized geo-spatial wealth index for households in Africa, Asia, and the Americas (calculated by the Demographic and Health Surveys Program) with satellite images of nighttime lights in these countries, the scientists found that 19 percent of the Earth’s total settlement footprint had no detectable artificial radiance. The majority of unlit settlements were in Africa (39 percent) and Asia (23 percent). Moreover, if only rural areas were considered, these percentages rose to 65 percent for Africa and 40 percent for Asia. These results indicate a strong association between increasing percentages of unlit communities and decreasing economic well-being.

While government agencies usually prioritize the expansion of electricity access for urban rather than rural areas, the researchers stress that rural electrification is crucial for increasing economic wellbeing, health, and education. Since the United Nations Sustainable Development Goals (SDGs) specifically include “access to affordable, reliable, sustainable, and modern energy for all,” identifying all the areas where such access is lacking is crucial.

“If applied over time, the method we used in our study could provide opportunities to track well-being and progress toward the SDGs. In terms of policy, it can help better inform energy policy around the globe and can also be helpful in shaping aid policy by ensuring that we are reaching those remote rural areas that are likely energy poor. In addition, it could be useful to detect signs of sustainable and environmental management of lighting in the developed world,” concluded study co-author Shonali Pachauri, a researcher at IIASA.

The study is published in the journal Nature Communications.

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By Andrei Ionescu, Earth.com Staff Writer