The number of listed threatened species in Australia’s world heritage northern rainforests has increased by 25% since 2020, as ecologists say they are now clearly observing the long-predicted impacts of global heating.
The management and conservation authority for the Unesco-listed Queensland wet tropics this week handed its latest environmental report to the state government, containing “sombre but pragmatic” warnings about the declining health of some species, including the ringtail possum, that were believed robust when the area was given international protection in 1988.
“The insidious and damaging threat posed by invasive species and diseases, and the impacts of climate change, present real danger to the continuing integrity of the area’s biodiversity,” the report says.
It found a number of additional species – including endemic rainforest frogs, ringtail possums, high-altitude birds and myrtle plants – that were considered secure at the time of world heritage listing, “now face significant challenges from accumulated and compounding threats”.
Stephen Williams, a rainforest ecologist and a director of the Wet Tropics Management Authority, says his analysis showed there had been a 25% increase to the number of listed threatened vertebrate species in the area in the past three years.
Williams said previously predicted declines in some species were now being observed first-hand.
“It’s primarily climate … it’s almost entirely climate,” Williams said.
“The wet tropics as a world heritage area is in relatively good shape … but there is a rapidly increasing number of species that are either on the threatened list, or soon be on the threatened list.
“This sort of thing is happening rapidly and it takes years to get something listed as threatened. Governments tend to only want to fund or even talk about things that are officially listed.
“But whatever statistic we use, the problem is actually twice as bad as that. More species are declining than are currently listed.”
Williams said the situation had left the wet tropics “at a real risk of losing the very things it was made a world heritage area to protect”.
Many species in the wet tropics have been affected by severe heatwave or droughts. More than 23,000 spectacled flying foxes were killed – about 30% of the entire population – during a two-day heatwave in November 2018.
Williams said it was now clear that creeping average temperature increases – as opposed to short-term weather extremes – were also contributing to biodiversity stress in cool-adapted upland species like the ringtail possum, and some frog and bird species.
“Some of these are showing signatures of slow decline in increasing heat,” Williams said.
“For those particular species … it’s hard to imagine what you can do beyond climate action.”
Another increasing threat to rainforest biodiversity has come from bushfires. Previously the damp rainforest had been considered a natural fire barrier, but in recent years bushfires have caused serious damage.
“The wet tropics region can expect more frequent and more intense fires due to hotter temperatures,” the report said.
“The capacity of the area’s endemic rainforest species to regenerate after fire is poorly studied.”
In a statement, the management authority said “there remains a narrow window where we can bring threatened species back from the brink through bold new programs and partnerships”
Eastern Kuku Yalanji woman Christine Grant, the chair of the authority, said there was no “silver bullet”.
“The best available science tells us the way to protect threatened species is through long-term planning, rethinking our investments, and prioritising landscape-scale restoration to tackle climate change with better fire management and projects that reduce other threats such as invasive species,” Grant said.
“World heritage listing for the wet tropics has provided a measure of protection to save species, but invasive pests, diseases and more frequent and extensive storms and other natural disasters, particularly fires, threaten this internationally significant region.”
