Two million species are at risk of extinction, a figure that is double previous UN estimates, new analysis has found.
While scientists have long documented the decline of species of plants and vertebrates, there has always been significant uncertainty over insects, with the UN making a “tentative estimate” of 10% threatened with extinction in 2019.
Since then, more data has been collected on insects, showing the proportion at risk of extinction is much higher than previously estimated. Because there are so many insect species, this doubles the global number of species at risk, according to the paper, published in Plos One on Wednesday.
Lead researcher, Axel Hochkirch, from the Musée National d’Histoire Naturelle in Luxembourg, said: “What our study does is really highlight that insects are as threatened as other taxa. And because they are the most species-rich group of animals on our planet, this is really something which should be addressed.”
Understanding what is happening to global insect populations has been challenging because of the lack of data – but 97% of all animals are invertebrates. Of that group, about 90% are classified as insects. They provide vital ecosystem services: pollinating crops, recycling nutrients into soils, and decomposing waste. “Without insects, our planet will not be able to survive,” Hochkirch said.
The team looked at all European species on the International Union for Conservation of Nature’s red list of threatened species. This is considered the most comprehensive source of information on species at risk. They found a fifth of European species were at risk of extinction, with 24% of invertebrates at risk, as well as 27% of all plants and 18% of vertebrates.
These numbers were then extrapolated to make a global estimate of total species at risk of extinction. Apart from insects, estimates remained more or less the same as those made by the UN’s Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (Ipbes) in 2019.
“This comprehensive analysis of 14,669 continental red list assessments for European animal and plant species suggests that 2 million plant and animal species are threatened with extinction,” researchers said.
UN representatives declined to comment on the study itself. Anne Larigauderie, executive secretary of Ipbes, said the second Ipbes Global Assessment Report is due in 2028, and it was “likely that the estimates and messages from the first Global Assessment Report will be updated and augmented”.
“It is perhaps most important to remember that whether the figure being used by policy- and decision-makers is 1 million or even more – the urgency and priority of the global biodiversity crisis remains,” Larigauderie said. “We are losing biodiversity and nature’s contributions to people at rates never before seen in human history.”
The causes of these declines are well documented, and are driven by human activity: the expansion of agriculture resulting in the loss of natural habitats is the most significant driver, followed by overexploitation of natural resources, pollution, and residential and commercial development.
The paper said: “The finding of agricultural land-use change as a major threat to biodiversity has often been reported. However, our analysis is the most comprehensive and unequivocal to date reaffirming the magnitude of the impact of this threat at a continental scale.”
Hochkirch said: “This study shows we have a very high proportion of species which are threatened with extinction, but we can do something about it.” He highlighted the effectiveness of conservation efforts, particularly the increase in large predators across Europe, such as wolves, lynx, bears and white-tailed eagles. He added: “We see whenever conservation action is taking place, these improvements happen.”