In the next 50 years, human expansion is expected to encroach on over half of the Earth’s wildlife habitats, posing significant threats to biodiversity and increasing the risk of future pandemics, according to recent scientific findings.

Currently, humans have already transformed or occupied between 70% and 75% of the planet’s land.

A study published in Science Advances on Wednesday predicts that by 2070, the overlap between human and wildlife populations will grow across 57% of the Earth’s land, largely due to population growth.

“You have places such as forests where there are virtually no people, where we will start to see some more human presence and activities, and interactions with wildlife,” said Neil Carter, the principal investigator of the study and an associate professor of environment and sustainability at the University of Michigan in the US.

“People are increasing their pressures and negative impacts on … species, which is something that we’ve seen already for many years. It is part of the cause of the biodiversity-loss crisis that we’re in,” he said.

As humans and animals increasingly share crowded landscapes, the greater overlap could lead to heightened risks of disease transmission, loss of biodiversity, and conflicts such as animals being killed by people or wildlife consuming livestock and crops.

Biodiversity loss is the primary driver of infectious disease outbreaks, with about 75% of emerging diseases in humans being zoonotic—transmitted from animals to humans. Diseases of global concern, including COVID-19, mpox, avian flu, and swine flu, are likely rooted in wildlife.

Kim Gruetzmacher, a wildlife conservation veterinarian and researcher not involved in the study, emphasised the importance of understanding where human and wildlife overlap to prevent “the acceleration of viral spillover from wildlife.”

“The vast majority – up to 75% – of emerging infectious diseases (which can lead to epidemics and pandemics) stem from non-human animals, the majority of which originate in wildlife,” Gruetzmacher said. “It is not the wildlife itself which poses a risk, but our behaviour and specific contact with it.”

Researchers at the University of Michigan used projections of human population growth and land use to forecast future overlaps with the habitats of over 22,000 species.

They found that regions with already high population densities, such as India and China, will see the most significant increases in human-wildlife overlap.

Additionally, agricultural and forested regions in Africa and South America are expected to experience substantial overlap. Conversely, in some areas, like over 20% of Europe’s land, the overlap is projected to decrease.

The research can guide policymakers “to avoid the human and wildlife conflicts and focus more on the conservation of species richness,” said Deqiang Ma, the lead author of the study and a postdoctoral research fellow at the University of Michigan Institute for Global Change Biology.

Rob Cooke, an ecological modeller at the UK centre for Ecology and Hydrology, who was not involved in the study, said it gave a “broad picture overview of what’s happening and what could change”, but more research was needed into “what kinds of species and how are we going to interact, and what kind of repercussions does it have”.

 

 

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