Climate Change Threatens Australia’s Ecosystems

By Oliver Milman, The Guardian

Climate change is compounding existing threats to Australia’s forests, wetlands and deserts, with several key landscapes now at risk of total collapse, a landmark series of new studies have found.

An assessment of 13 ecosystems across Australia, ranging from the wet tropics of far north Queensland to rare shrubland in Western Australia, found what researchers call a “worrying” climate change impact that adds to existing harm caused by urban development, agriculture and invasive species.

Forests perched on the mountains of Lord Howe Island are drying out because the damp clouds that envelop them are becoming sparser.
Credit: Stuart Parker/AAP/The Guardian

The research is the first of its kind to assess Australian ecosystems based on the International Union for Conservation of Nature’s benchmark Red List criteria which has, until recently, focused on the status of individual animal and plant species rather than whole landscapes.

Under the Red List criteria, eight of the studied Australian ecosystems would be classified as “endangered” or “critically endangered”, with just the Lake Eyre wetlands considered in the “least concern” category.

Professor David Keith of the University of NSW, who led the international team to expand the Red List to ecosystems, said the Australian study, which he also led, shows that climate change is leaving its imprint on vast swaths of the environment.

“The overall picture is one of increasing risk,” he told Guardian Australia. “Climate change is amplifying other threats. It’s the most pervasive threat because it cuts across everything, whereas habitat loss and diseases are specific to individual systems. It’s very worrying.”

Changes in the climate – Australia has warmed by nearly 1°C over the past 100 years – are having a variety of effects, the research published in Austral Ecology found.

A decline in rainfall in south-west Western Australia is threatening incredibly diverse but rare shrublands that require moisture during a crucial window for seedlings during the year. Meanwhile, forests perched on the mountains of Lord Howe Island are drying out because the damp clouds that envelop them are becoming sparser.

A separate study of an area of Antarctica shows that sea sponges could lose out to algae if sea ice thins, increasing the amount of sunlight that enters their marine environment.

Ecosystems face other threats – for example, the wet tropics have become fragmented due to land clearing for cane sugar farming and other industries. This means that cassowaries, which are crucial to dispersing seeds and maintaining plant diversity, have less space to roam and are increasingly being killed by cars or having their young picked off by predators.

“Our ecosystems are becoming more simple, they are losing species, which reduces these systems’ resilience to change,” Keith said.

“In some cases it’s due to changes in land use, such as the clearing of woodland, and in others it’s invasive species, such as water mould, goats, deer, cats and foxes.

“Native herbivores are being taken out, which means that ecosystem tasks such as the turning over of soils isn’t being done. This has cascading effects – species that aren’t directly impacted [on] find they can’t persist because they can’t reproduce.”

This decline has a direct impact upon humans as well as other affected species, Keith said, citing the Cumberland plain woodland system near Sydney.

“This woodland has been extensively cleared for grazing and cropping to the extent that just 10 percent of its area remains,” he said. “The native mammals have become extinct and there are sustained declines in the bird species. The system is at a point where it’s almost starting to consume itself, it’s collapsing.

“Apart from the intrinsic values of nature, urban areas need open spaces to keep populations sane and healthy. That, essentially, is what we are losing.

“The rate of decline in Australia is up there among the worst in the world. We need to turn that around. That said, the major threats have been operating for a relatively short time on a global scale, around the last 150 years, so there’s still a lot to work with.”

The research comprised of making detailed assessments over the extent of an ecosystem and then analysing the trends of key species within the area. 

Australia contains more than 5 percent of the world’s plants and animals, with 87 percent of them endemic, meaning they aren’t found anywhere else on Earth. However, Australia has one of the worst extinction records in the world, with 50 species vanishing in the past 200 years, including 27 mammal species.

Alongside climate change, habitat loss remains a challenge in Australia despite land-clearing laws slowing historical removals. WWF estimates that between 3m hectares and 6m hectares of rainforest and temperate forest, mainly stretching across New South Wales and Queensland, could be lost between 2010 and 2030 on current trends.

Reprinted from The Guardian with permission.