Human-Wildlife Overlap Projected to Surge by 2070, University of Michigan Study Finds

The world’s landscapes are entering a new ecological era. A groundbreaking study from the University of Michigan reveals that by 2070, more than half of Earth’s land could witness a dramatic rise in human-wildlife overlap, driven primarily by population growth. These findings, published in Science Advances, present significant implications for urban planners, conservationists and global environmental policies.

“We found that the overlap between populations of humans and wildlife will increase across about 57% of the global lands, but it will decrease across only about 12% of the global lands. We also found that agricultural and forest areas will experience substantial increases of overlap in the future,” Deqiang Ma, the study’s lead author and postdoctoral research fellow at the U-M Institute for Global Change Biology in the School for Environment and Sustainability, said in a news release.

The study utilized an innovative index combining human population projections with the spatial distributions of 22,374 species of terrestrial amphibians, birds, mammals and reptiles. These projections were derived from climate niche data and estimates of future human settlements based on economic development and demographic trends.

“The index we created showed that the majority of global lands will experience increases in human-wildlife overlap, and this increasing overlap is the result of the expansion of human population much more so than changes in species distributions caused by climate change,” Ma added.

Worsening Biodiversity Crisis

Regions like China and India, with already high human densities, are expected to see more intense overlaps, but new hotspots are emerging.

“[A]nother area of major concern are forests, particularly in forests in Africa and South America where we’re seeing a large increase in the overlap in the future,” Neil Carter, the study’s principal investigator and associate professor of environment and sustainability, said in the news release. “The reason that is concerning is because those areas have very high biodiversity that would experience greater pressure in the future.”

In Africa and South America, the study projects drastic declines in species richness, with mammal diversity declining by 33% and 21% respectively. This loss is troubling given the intricate ecological roles these animals play.

Complex Interactions Between Humans and Wildlife

“This means that all sorts of novel interactions, good and bad, between people and wildlife will emerge in the near future,” added Carter.

The study highlights both threats and opportunities from these interactions. While increased human-wildlife encounters can spur the emergence of new diseases, like the COVID-19 pandemic, certain species also provide invaluable ecosystem services.

“There are cases of human-wildlife interactions that are both good and bad, but we anticipate that they’re going to become more pronounced,” Carter said.

Birds that control agricultural pests may decline in areas with increased human activity, yet scavengers like hyenas can reduce disease by cleaning waste.

“Hyenas and other species that are vilified or persecuted because they are scavengers provide a lot of disease reduction benefits,” he added.

Strategizing for Future Coexistence

The findings call for adaptive and equitable conservation strategies. Traditional approaches — such as establishing protected areas — are becoming increasingly impractical.

“There’s also a significant environmental justice argument around the validity of telling communities that may have lived in a certain area for generations that they have to move,” Carter added.

Creative solutions, including habitat corridors and temporary protected areas, are crucial. Engaging local communities in these efforts is equally important.

“We care a lot about which areas can support populations of endangered species, like tigers, and how human communities interact with these species,” added Carter.