Human activities are causing a decline in global biodiversity, according to a synthesis study published in the journal Nature. Researchers compiled data from around 2,100 studies, comparing biodiversity at nearly 50,000 human-affected locations with an equal number of unaffected reference sites. The dataset of 3,667 independent comparisons spans all major organismal groups and habitats.
According to The Guardian, the study reveals that humans are having a highly detrimental impact on biodiversity worldwide, with negative effects observed across all groups of organisms and ecosystems.
"Our findings show that all five factors have a strong impact on biodiversity worldwide, in all groups of organisms and in all ecosystems," said François Keck at the Swiss Federal Institute of Aquatic Science and Technology (Eawag) in Switzerland. This underscores the pervasive influence of human pressures on natural environments.
The study identifies five main drivers of biodiversity decline: habitat change, direct exploitation of resources such as hunting or fishing, climate change, pollution, and invasive species. All five of these human pressures shift the composition of biological communities, leading to effects on biodiversity.
Vertebrates, such as reptiles, amphibians, and mammals, are particularly vulnerable to species loss in all biogeographic regions, experiencing declines. The populations of vertebrates tend to be smaller compared to those of invertebrates, increasing the risk of extinction—a trend also observed in affected areas.
The most marked changes in species communities are observed among microbes and fungi, probably due to their short life cycles and high dispersal rates, which allow them to respond quickly to environmental changes. These groups exhibit higher rates of community composition change, reflecting their rapid adaptation to altered environments.
"It is one of the world's largest syntheses ever conducted on the effects of humans on biodiversity," said Florian Altermatt, a professor of aquatic ecology at the University of Zurich and Eawag, in a press release about the study published in the journal Nature. This comprehensive analysis provides a detailed picture of human impacts on ecosystems.
The researchers report that the number of species in sites affected by human activity is, on average, nearly 20% lower compared to those not influenced. Both the number and composition of species have been affected globally by human activity, resulting in biodiversity loss and changes in species communities.
Environmental pollution and habitat changes, such as deforestation or the leveling of meadows, have a particularly negative impact on species numbers and the composition of species communities. Pollution introduces new substances into habitats that destroy or weaken the organisms living there, whether accidental, like oil spills, or deliberate, such as pesticide use.
"The human influence that we find is sometimes so strong that there are even signs that could indicate a complete collapse of the species communities," explained Altermatt. This illustrates the severe consequences of unchecked human activities on ecological balance.
In mountainous regions, specialized plants are at risk of being displaced by species from lower altitudes as the climate continues to warm. This process is known as the elevator to extinction, as high-altitude plants have nowhere else to go, exacerbating the risk of their extinction.
The findings, with their distinct character and global validity, indicate the global threats to biological diversity. The researchers stated, "Bending the curve of contemporary biodiversity loss and change is one of the greatest challenges facing our society," emphasizing the need for ambitious targets to reverse biodiversity change.
"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," commented Professor Alexandre Antonelli, director of science at Kew Gardens. His remarks underscore the value of the study's comprehensive approach.
"This is a useful and important analysis, but the findings reveal no great surprises," said Lynn Dicks, professor of ecology at Cambridge University. She added, "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."
The article was written with the assistance of a news analysis system.