In the most comprehensive research of its kind to date, the team looked at the population density changes of 71,114 species across the globe. And they found the impact of human industrialization on these 5,969 mammals, 11,162 birds, 10,150 reptiles, 7,316 amphibians, 24,356 fish, and 12,161 insects is significantly more alarming than previously thought.
Birds are faring worst followed by mammals, amphibians, reptiles, fish and insects - although there are more unknowns in the latter three categories.
Catherine Finn, PhD student at Queen’s University Belfast and leading author on the research, said: “Almost half of animals on Earth for which assessments are available are currently declining.
“To make matters worse, many of the animal species that are thought to be non-threatened from extinction, are in fact progressively declining.”
Worldwide erosion of biodiversity is one of the most critical challenges facing humanity in the coming decades. It threatens the very ecosystems life depends on as well as food production, the spread of diseases and global economic stability.
According to this traditional method, 28% of life on Earth is threatened with extinction.
The academics behind this groundbreaking research adopted a new approach using a global-scale analysis of a different measure of extinction risk called “population trends” to see whether the population sizes of species are declining, remain stable or are getting better over time.
Using this approach, they found the magnitude of the extinction crisis is considerably more severe than shown by the traditional measure based on threat categories, with an alarming 48% of species declining towards extinction and only 3% showing signals of recovery.
Decreasing vs unknown(Image: QUB)
The team behind the report say the findings show the global crisis of biodiversity extinction is failing to compensate for lost species with the evolution of other species that could take their places in nature.
Their research also found 33% of species currently considered “safe” by the IUCN conservation categories are in fact declining towards risk of extinction.
Dr Daniel Pincheira-Donoso, Senior Lecturer in Evolutionary Biology and Macroecology at Queen’s University Belfast and the Principal Investigator of the project, said: “This new study method and global-scale analysis provides a clearer picture about the true extent of global erosion of biodiversity that the traditional approach cannot offer.
“Our work is a drastic alert about the current magnitude of this crisis that has already devastating impacts on the stability of nature as a whole, and on human health and wellbeing.”
Species in decline(Image: QUB)
The study was funded by the UKRI (NERC) QUADRAT Doctoral Training Programme.
“We show a widespread global erosion of species, with 48% undergoing declines, while 49% and 3% of species currently remain stable or are increasing, respectively,” the report’s abstract states.
“Geographically, we reveal an intriguing pattern similar to that of threatened species, whereby declines tend to concentrate around tropical regions, whereas stability and increases show a tendency to expand towards temperate climates.
“Importantly, we find that for species currently classed by the IUCN Red List as ‘non-threatened’, 33% are declining.
“Critically, in contrast with previous mass extinction events, our assessment shows that the Anthropocene extinction crisis is undergoing a rapid biodiversity imbalance, with levels of declines (a symptom of extinction) greatly exceeding levels of increases (a symptom of ecological expansion and potentially of evolution) for all groups.
