Earth's species 'on cusp of' sixth mass extinction

The world will get an update of the Red List of Threatened Species, the authoritative catalogue of how many of the planet's animal and plant species are teetering on the brink of extinction due to human activity.

Experts for the International Union for the Conservation of Nature (IUCN), which is holding a world congress in the French city of Marseille, have assessed nearly 135,000 species over the last half-century, and almost 28 percent are currently at risk of vanishing forever.

Habitat loss, overexploitation and illegal trade have hammered global wildlife populations, but scientists say they are increasingly worried about the looming threats of climate change.

Sixth mass extinction

Asked if we are on the cusp of the sixth mass extinction, Craig Hilton-Taylor, IUCN's Head of Red List Unit, told AFP news agency: "If we look at extinctions every 100 years since 1500, there is a marked inflection starting in the 1900s. The trend is showing that we are 100 to 1,000 times higher than the 'background', or normal, extinction rates. I would certainly say that the red list status shows that we're on the cusp of the sixth extinction event [in the last 500 million years]. 

"If the trends carry on going upward at that rate, we'll be facing a major crisis soon."

"There are lots of species around the world that we would almost certainly have lost. The Red List process drew attention, for example, to the plight of the Arabian oryx and led to conservation efforts –– taking the animals out of the wild, captive breeding, reintroductions," he said.

"We've seen species very nearly extinct that are thriving now."

READ MORE: Extinction, disease, heat to hit Earth sooner than feared – UN draft report

Climate crisis 

About climate crisis being rarely cited as a driver of extinction, Hilton-Taylor said: "It is obvious for the polar bears because of the direct link between sea ice cover and global warming, but with other megafauna it's a lot harder to detect the impacts of climate change."

He said, there is evidence pointing to climate crisis for the increasing frequency and intensity of wildfires, "but when experts record threats to a species they may put 'increased fire frequency', not climate change."

"The chytrid fungus is wiping out amphibians all around the world, and we are pretty sure that its emergence is very much linked to climate change. But with the evidence we have now, the category of threat is invasive species, not climate change," he said. 

READ MORE: A million species at risk of extinction - scientists