New study suggests rural populations are seriously misrepresented in national censuses.

We might be sharing the planet with far more people than we think — possibly billions more. A new study, published in the journal Nature, reveals that rural populations around the world are being seriously neglected in global population estimates, raising big questions about how we plan for things like healthcare, infrastructure, and disaster response.

The United Nations estimated there were 8.2 billion people on Earth as of last summer. But new research suggests that number could be off — by hundreds of millions, or even several billion. This surprising claim comes from a team led by postdoctoral researcher Josias Láng-Ritter at Aalto University in Finland.

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The three researchers examined population data connected to 307 large dam resettlement projects across 35 countries.

These are situations where governments had solid, verified data on how many people were displaced. Using that information, the researchers tested how accurate five major global population datasets were in estimating rural populations.

The results were striking: every dataset underestimated rural populations by a wide margin—ranging from 53% to 84%. Even the most accurate dataset counted only about half the actual number of people in rural areas.

Among countries where rural population has been undercounted in higher numbers, the researchers named China, Brazil, Australia, Poland, and Colombia. In all of these countries, rural population is significantly underestimated by all five datasets.

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These gridded population maps are important tools used in everything from disaster planning to disease tracking to resource distribution. But they rely heavily on satellite imagery and models built mostly around urban populations. When it comes to rural areas — especially in low-income countries — the data just doesn’t hold up.

The study’s authors say fixing this population inaccuracy won’t be easy as it implies overhauling census management, administrative effort, and more spending.

A larger human population may be a reason for concern, due to limited resources, but while some worry about overpopulation, others argue the real danger is actually population decline.