Nearly half of the world’s species are in rapid population decline, study finds
New research has found that “sustained population declines” among animal populations are more alarming than previously thought.
The loss of wildlife is ‘one of the most alarming syndromes of human impacts’, according to a new study published in Biological Reviews.
The researchers found that of the more than 71,000 species they analyzed – mammals, birds, amphibians, reptiles and fish – 48% are experiencing population declines, while 49% are stable and only 3% growing.
The findings painted “a considerably more alarming picture” than conservation estimates by the International Union for Conservation of Nature (IUCN) Red Listindicates the report.
Populations of “non-threatened” species are declining
The conservation status of wildlife is traditionally monitored by the IUCN Red List which classifies species according to their degree of danger, such as Near Threatened, Vulnerable, Endangered and others.
The latest study found that 33% of species deemed ‘not threatened’ are suffering from population decline, which it says is ‘a symptom of extinction’.
While the IUCN indicates that 28% of species are threatened, this red list is not the only indicator of risk of extinction.
The species may be considered “non-threatened”, but the fact that their population is declining may mean that they are heading towards extinction, the report warns.
While echoing concerns expressed in the study, IUCN Red List Manager Craig Hilton-Taylor said CNN his results could “overstate the situation”, since the data is collected on a wide range of animal groups, including those for which data is lacking.
He insists this is a less robust measure than that of the IUCN which looks at “species trends over much longer time periods”.
Biodiversity “on the brink of an extinction crisis”
The study points out that amphibians are particularly affected, highlighting “major gaps in our knowledge of population trends, especially for fish and insects”.
When a species’ population drops too low, it cannot contribute as much as it could to the ecosystem, the report says.
For example, overhunting of sea otters enabled a boom in kelp-eating sea urchins that decimated kelp forests in the Bering Sea, driving the kelp-eating Steller’s sea cow to extinction.
The reduction of one species is enough to throw the whole ecosystem out of balance, which has a ripple effect on other populations that can snowball into large-scale disruption.
The transformation of wild landscapes into urban areas or agricultural land is considered by scientists to be one of the main factors in the loss of wildlife because it destroys their natural habitat. But climate change is also a major driver of species decline, and its impact is worsening as the planet warms.
Declines revealed in the study tend to be concentrated around tropical areas, while stability and increases are more likely to affect temperate climates.
Politicians aim for ‘minimum goal’
Aimed at habitat preservation, some initiatives such as The “30 x 30” objective of COP15which aims to protect 30% of land and oceans by 2030, have gained support.
More than 100 countries accepted this commitment last fall.
IUCN experts say this target is the minimum that politicians should be aiming for, with many studies calling for protecting up to 70% or more of wild landscapes.
Wildlife habitat is deteriorating in the EU, with 81% of natural habitat in an ‘unfavourable’ conservation status, according to a report by the European Environment Agency over the period 2013-2018.
The world currently protects around 17% of its land and inland waters and less than 8% of marine and coastal areas, according to a Report of the United Nations Environment Program released in 2021.