Human activity is accelerating biodiversity loss across the planet, according to a sweeping analysis synthesising data from over 2,000 studies.

Conducted by researchers from the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and the University of Zurich, the study examined nearly 100,000 locations worldwide and found “unprecedented effects on biodiversity” caused by human influence.

According to the paper Nature, the findings make clear the extensive and far-reaching consequences of human pressures on ecosystems across all continents.

Florian Altermatt, professor of aquatic ecology at the University of Zurich and head of Eawag, said: “It is one of the largest syntheses of the human impacts on biodiversity ever conducted worldwide.”

The researchers assessed biodiversity changes across terrestrial, freshwater, and marine environments, considering all major groups of organisms—from microbes and fungi to plants, invertebrates, fish, birds, and mammals. The results revealed that human activity alters the composition of biological communities, essentially changing which species live where.

In addition, species richness—defined as the number of species in a given area—was, on average, nearly 20% lower in locations affected by human influence compared to undisturbed sites.

The most pronounced declines were noted among reptiles, amphibians, and mammals. These groups typically have smaller population sizes compared to invertebrates, making them more vulnerable to extinction.

The study identified five key drivers of biodiversity decline: habitat change, resource exploitation (like hunting and fishing), climate change, invasive species, and pollution.

François Keck, lead author and a postdoctoral researcher in Altermatt’s research group, said: “Our findings show that all five factors have a strong impact on biodiversity worldwide, in all groups of organisms and in all ecosystems.”

Habitat degradation and pollution—often the result of agricultural expansion—were found to have especially harmful effects. Intensive farming, particularly arable agriculture, relies heavily on pesticides and fertilisers, which reduce biodiversity and alter the structure of ecological communities. While the impact of climate change remains less fully understood, it is already contributing to shifts in species distributions and ecosystem dynamics.

Keck said: “It’s not just the number of species that is declining. Human pressure is also changing the composition of species communities.”

Interestingly, the study also found variability in the degree and nature of human impacts depending on the location. In mountainous regions, for instance, species adapted to higher elevations are being replaced by those from lower altitudes—a phenomenon referred to as the “elevator to extinction,” as high-altitude species have nowhere else to move. This shift may not affect the total number of species but can still reduce biodiversity by homogenising ecosystems.

Before this research, no study had attempted to integrate such a vast range of biodiversity data across multiple habitats and organism groups on a global scale. Previous studies were often limited to specific locations or types of human influence, making it difficult to draw broad conclusions. This new analysis provides a critical baseline for understanding human-driven biodiversity change.

The authors described biodiversity loss as one of the greatest challenges facing society today and hope their work will serve as a vital benchmark for shaping future conservation policies.

Lynn Dicks, a professor of ecology at the University of Cambridge, praised the study as both “useful and important,” noting that while it offers no major surprises, it reinforces the urgent need for action.

She said: “We know that humans are hugely changing biodiversity across the planet, causing new and different communities of plants, animals and microbes to form, which can cope with the sometimes very harsh conditions we create.

“A big concern for me is how to ensure that those species that can live alongside us, many of which provide key ecological functions like pollination, decomposition and seed dispersal, have large enough populations and enough genetic diversity to continue evolving.”

Prof Alexandre Antonelli, director of science at Kew Gardens, said the paper showed with “unprecedented clarity the ubiquitous negative influence of human activities on nature”.

He added: “This is an excellent piece of research that demonstrates the importance of biological inclusion – from plants and fungi to mammals and fish – in assessing the impact of humans on biodiversity at local, regional and global scales.”

 

 

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