Is our little blue marble of a planet actually a lot more crowded than we thought? A new study suggests we’ve been significantly undercounting populations in rural areas, because of the grid-based method typically used to count people.
The grid idea is simple: Split the world into squares, and estimate the population in each square based on census data.
But because these estimations have mostly been calibrated in urban rather than rural settings, inaccuracies in rural areas have gone undetected, according to researchers from Aalto University in Finland.
Rural regions account for 43 percent of the world’s population – estimated to be just over 8 billion, at the last count – and if the calculations in this new study are correct then the number of unaccounted-for people could potentially stretch into the billions.
“For the first time, our study provides evidence that a significant proportion of the rural population may be missing from global population datasets,” says environmental engineer Josias Láng-Ritter from Aalto University.
“We were surprised to find that the actual population living in rural areas is much higher than the global population data indicates – depending on the dataset, rural populations have been underestimated by between 53 percent to 84 percent over the period studied.”
The team analyzed population data for the period 1975-2010, looking at the effects of dam construction work on people displacement – a scenario for which there is usually verifiable, on-the-ground data for.
Crunching the statistics on 307 dam projects across 35 countries, the researchers compared the official number of displaced people in these areas against the number of people thought to be there by five different major population datasets.
The significant disparity between the population estimates and the actual number of people moved in an area is ultimately because far less granular data is available for rural areas, the researchers say: including census data, health data, and infrastructure data.
“The results are remarkable, as these datasets have been used in thousands of studies and extensively to support decision-making, yet their accuracy has not been systematically evaluated,” says Láng-Ritter.
Not everyone is convinced. Scientists who weren’t involved in the study told Chris Stokel-Walker at New Scientist that improvements in satellite imagery and the quality of data collecting in some countries would make these discrepancies smaller.
However, there’s definitely a conversation to be had. Even if the miscount is more moderate, we could still be looking at a correction encompassing hundreds of millions of people.
Population estimates are crucial in everything from providing public services to estimating the impacts of climate change, and the team behind the new research wants to see more investment in population tracking in rural areas – to make sure these people don’t miss out.
“To provide rural communities with equal access to services and other resources, we need to have a critical discussion about the past and future applications of these population maps,” says Láng-Ritter.
The research has been published in Nature Communications.
