crunching

In November 2022, the UN celebrated that we were now 8 billion humans on Earth. They are estimates, of course, but beyond the figure, the really interesting thing is that in 2023 we do not reach the replacement rate and that humanity will reach its peak at the end of the century to, inevitably, start to fall. But… to what extent can we trust these accounts? It is something that has been on the table for some time and, according to a study of 2025, we have made a mistake in counting. So much so that we have left several hundred million people behind. Can we trust the numbers? “Calculating the number of people on the planet is an inexact science.” That was demographer Jakub Bijak’s comment to BBC in mid-2024, just when the World Population Prospects study. Something scientific is something exact, but the researcher also commented that the only thing you can be sure of when predicting population figures is the lack of certainty. That, be careful, does not mean that demographers take figures out of thin air. “It is a difficult thing based on our experience, knowledge and every piece of information we have access to,” said Toshiko Kanera, an expert in demographic forecasts. Demographers draw on the data and trends of each country since 1950, but… what if it had not been counted correctly? We are missing millions. In a 2025 study published in Natureresearchers at Aalto University in Finland show how the data sets handled by demographers “profoundly and systematically” underestimate population figures around the world. The serious thing is that we would be talking about hundreds of millions more people living on Earth. Example of the tools that demographers use in their analysis. Each one corresponds to a different bias Rural areas. Josias Láng-Ritter is one of the researchers in charge of the study and points to the accounts carried out in a specific segment: that of rural population. “For the first time, our study provides evidence that a significant proportion of the rural population could be missing from global population data sets,” he notes. As we say, we are not talking about a few million, but billions. “Depending on the data set used, rural populations have been underestimated between 53% and 84% in the period studied. The results are notable, since these data sets have been used in thousands of studies and have widely supported decision making, but their accuracy has not been systematically evaluated,” comments the researcher. The map shows the location of the 307 rural areas analyzed in the study. The populations reported in the graph were found to be underestimated by between 53% and 84% | Aalto University Biases. Attempts to review this data are not new, but previous research has focused on specific countries or urban areas. Researchers from Aalto University wanted to give a more global picture by comparing the five most used population data sets worldwide. They have used maps that divide the planet into high-resolution grids and have taken something very specific as a reference: resettlement figures from more than 300 rural dam projects in 35 countries. Why this bias of the dams? Because when a dam is builtthe population that lives in the area that will be flooded is relocated and accurate resettlement data is usually available. Comparing that population data from 1975 to 2010, the researchers found that the 2010 maps were more accurate, but still left out between 32% and 77% of the rural population. Between 2015 and 2020 the data sets were updated, but demographers continue to believe that underestimation of the rural population continues to exist and is a problem that persists in all regions of the world. Consequences. And we are talking about a problem whose resolution is complex. According to the researchers, no matter how much the data is reviewed, it is a structural problem. Governments do not have the resources to collect accurate data in these rural regions, there is a huge discrepancy between the real population and that reported on the population maps used to carry out demographic studies and that influences decision making. Average percentage of rural population underestimated (red and orange) and overestimated (blue) | Aalto University And it’s important. Current estimates place 43% of the 8.2 billion inhabitants of the world in rural areas -about 3,526 million people- and if we take into account that it is a percentage that has been underestimated between 53% and 84%, we are not talking about a small population, precisely. And it is essential to know exactly how many we are for a simple reason: the redistribution of resources. No data. The lack of accurate demographic records can affect political decision-making. Ritter gives the example of social decisions. “In many countries, there may not be enough data available at the national level, so they rely on global population maps to support their decisions: Do we need a paved road or a hospital? How much medicine is needed in a specific area? How many people could be affected by natural disasters like earthquakes or floods?” he says. Doing quick math, in the best scenario – that of 53% deviation in the rural population – we would be talking about 1,869 million people who would not have been counted. In the worst case, in that of the 84% not registered, we would talk about 2,962 million people. In the Nature study, they give the example of Paraguay, which in the 2012 census may have left out a quarter of the population. Reviewing the methods. In the team’s analysis, there are countries that fare better than others. They point to Finland as an example of reliable data, even in rural regions, because they began keeping digital records of the population 30 years ago. However, in countries where this thorough digital registration has taken longer to be implemented due to crises of any kind, the differences between the real population and the estimated one can be significant. “To provide rural communities … Read more