For the first time since the era of the dinosaurs, there are now more species becoming extinct than new ones evolving, according to a British leading biodiversity expert.
Simon Stuart, chair of the Species Survival Commission for the International Union for the Conservation of Nature (IUCN) – the body which officially declares species threatened and extinct – said that point had now “almost certainly” been crossed.
The main reasons mentioned for that worrisome trend were the destruction of natural habitats, hunting, the spread of alien predators and disease, and climate change.
Extinction is part of the constant evolution of life, and only 2-4 percent of the species that have ever lived on Earth are thought to be alive today. However fossil records suggest that for most of the planet’s 3.5 billion year history the steady rate of loss of species is thought to be about one in every million species each year.
The IUCN calculated in 2004 that the rate of loss had risen to 100-1,000 per millions species annually, however skeptics have pointed out that those calculations are based on extrapolation and leave a huge margin for error.
Stuart’s answer is that the IUCN figure was likely to be an underestimate of the problem, because scientists are very reluctant to declare species extinct even when they have sometimes not been seen for decades, and because few of the world’s plants, fungi and invertebrates have yet been formally recorded and assessed.
The calculated increase in the extinction rate should also be compared to another study of thresholds of resilience for the natural world by Swedish scientists, who warned that anything over 10 times the background rate of extinction – 10 species in every million per year – was above the limit that could be tolerated if the world was to be safe for humans, he added.
“No one’s claiming it’s as small as 10 times. There are uncertainties all the way down; the only thing we’re certain about is the extent is way beyond what’s natural and it’s getting worse.”