SYDNEY—The koala is under threat from climate change, according to new research which shows rising carbon dioxide levels are killing nutrients in the plants they eat.
Lab tests have revealed that global warming is stripping the goodness from eucalypt leaves, and the University of Sydney researchers behind the study say the koalas that rely on them don't have enough time to adapt to the change.
"What currently may be good koala habitat may well become, over a period of not so many years at the rate that carbon dioxide concentrations are rising, very marginal habitat," lead researcher Professor Ian Hume said.
"I'm sure we'll see koalas disappearing from their current range even though we don't see any change in tree species or structure of the forests."
Professor Hume will present new research at a major science conference in Canberra on Wednesday 7th showing that increases in CO2 decrease levels of "good" nutrients and increase toxic nutrients in eucalypt leaves.
This change will mean eucalypt species with high protein content will become unbeneficial to the koala as the so-called "anti-nutrients" such as tannins bind the protein making it unusable.
"If there is a significant rise in CO2 concentration in the atmosphere, which we're already seeing, that's going to push the ratio of nutrients to anti-nutrients even lower by increasing the concentration of these carbon-based anti-nutrients," he said.
When asked how long it would take for koalas to be affected, he said: "I would've thought a few years ago when we first did these experiments that you might see something in a hundred years."
"But at the rate at which things are going, I suspect that we might see changes within our lifetimes," Prof Hume said.
He will tell the Academy of Sciences conference that koalas had "nowhere near enough time" to adapt to the changes in nutrient content.
They may be forced to travel in search of more nutrient-rich species, increasing their risk of being hit by vehicles or eaten by predators, the researchers warned.
The team believes the eucalypt will also be affected by rising temperatures, with some so sensitive to heat that even a one-degree shift will affect their growth.
The marsupials could be left with less temperature-sensitive species that are not suitable for koala feed.
The group studied the four marsupials that eat eucalypt foliage - koalas, the greater glider, common ringtail possum, and common brushtail possum - and found koalas most sensitive to the change.
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