Night satellites orbiting the Earth can be a new way to identify economic inequality.
Despite the success in reducing global poverty over the last two decades, nearly one billion people continue to live without access to reliable electricity, which in turn impacts health and welfare and impedes sustainable development.
Knowing where these people are is crucial if aid and infrastructure are to reach them.
Now, a new IIASA-led study proposes a method to estimate global economic wellbeing: the use of nighttime satellite images.
Researchers have been using satellite images of Earth at night to study human activity for over 30 years, and it is well established that these images can help map issues like economic growth, poverty and inequality – especially in places where such data is lacking.
Many impoverished countries lack the resources to conduct detailed surveys into the state of their citizens and the best ways to alleviate poverty. For example, 14 African countries have been unable to conduct any poverty surveys in the last decade.
However, satellites can offer an alternative, mapping out towns and villages while assessing economic conditions more cheaply and effectively than governments can. In developing countries, areas that are unlit at night generally indicate limited development, while brightly lit areas indicate more developed areas like capital cities where infrastructure is abundant.
In their study, which was published in Nature Communications, IIASA researchers and others from various institutions specifically focused on the data from unlit areas to estimate economic wellbeing.
“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,” explains study author and IIASA Strategic Initiatives Program Director, Steffen Fritz.
“By identifying those unlit areas we can target interventions for poverty alleviation and places to focus on to improve energy access.”
Researchers used a harmonised geospatial wealth index for households in various countries across Africa, Asia, and the Americas calculated by the Demographic and Health Surveys (DHS) program, which places individual households on a continuous scale of relative wealth from poorer to richer.
They combined that data with satellite image data of global nighttime lights in countries and found that 19 percent of the planet’s total settlement footprint had no detectable artificial radiance associated with it.
The majority of unlit settlement footprints were found in Africa with 39 percent and Asia with 23 percent. If only rural unlit infrastructure is considered, those numbers rise to 65 percent for Africa and 40 percent for Asia.
“We were able to map and predict the wealth class of around 2.4 million households for 49 countries spread across Africa, Asia, and the Americas based on the percentage of unlit settlements detected using nighttime light satellite images with an overall accuracy of 87%,” says IIASA Novel Data Ecosystems for Sustainability Research Group lead, Ian McCallum, who led the study.
The researchers note that government agencies typically prioritise expanding electricity access for urban, rather than rural areas.
Rural electrification however holds great promise for increasing wellbeing and can also have significant positive impacts in terms of household income, expenditure, health and education.
“If applied over time, the method we used in our study could provide opportunities to track wellbeing and progress towards the SDGs [The UN Sustainable Development Goals]. 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,” says Transformative Institutional and Social Solutions Research Group leader, Shonali Pachauri.
The use of satellites can go further than just fighting poverty, too.
India has used its satellite program to better predict rainfall, storms and other weather phenomena. With its system of weather satellites, the Indian government can give farmers recommendations on what foods to plant, and when and where to plant them for optimum results.