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What the Melomys extinction means for Australia’s ecosystem

Australian species are some of the most at risk of climate change extinction

by Tanya Pham and Ross Cordato, 18 March 2019

Three winters ago, Australian researchers discovered that the island of Bramble Cay off the coast of Queensland was officially rat free. However, the mosaic-tailed rat did not disappear due to predators or habitat loss, but rather its own climate caused its extinction.

Last month, the Australian Federal Government officially recognised that the Bramble Cay melomys (Melomys rubicola) was the first mammalian extinction resulting from human-induced climate change. The Government’s recovery plan to prevent the extinction of the Bramble Cay melomys was not enough to save the species. 

“There should be something like a coronial inquest after extinction events, [to assess] what caused he extinction or the failure to prevent it, in order to attribute responsibilities [to those who caused it],” said Professor John Woinarski, Deputy Director of the Threatened Species Recovery Hub and Professor at Charles Darwin University. The extinction of the small rodent marked the turn of a new era into what the Scientific Reportsjournal has described could be the next mass extinction and raises questions about the future survival of other species. 

A study released in 2014 by the Threatened Species Recovery Hub(TSRH) said Australia’s mammal extinction rate was the world’s highest, with more than 10 percent of species wiped out since Europeans settled the country two centuries ago. Australia is cited as one of the most vulnerable areas of species extinction due to its size, remoteness and extreme weather. 

This rate of extinction is not going to slow down anytime soon, with the TSRH now predicting that 10 Australian birds and seven mammals are likely to become extinct over the next 20 years, if current management continues. The Western Ground Parrot (Pezoporus flaviventris), a small green bird now only found in two Western Australian National Parks, make up a fraction this statistic with only 150 of its species currently in the wild.

Western Ground Parrot 
(Photo by Jennene Riggsfor ‘Secrets at Sunrise’ (2017))

The parrot population’s biggest threat is land clearing of its habitat which exposes the bird to predators. It is also threatened by wildfires in the region, with rising global temperatures creating the risk of more wildfires. “There’s a few species that are really going to be challenging to prevent the extinctions of, like the parrot,” said Woinarski. “In the tropical rainforests of Western Australia, [there is an] increased likelihood of fire due to climate change, resulting in repeatedly extremely hot days and droughts which increase the risk of fire… it will have a massive impact,” he said.

“I just think it’s incredibly sad… it’s going to take devastating and actual effects of climate change like [the melomys] to get people who need to take it seriously to take it seriously,” said Bailey Chappel, Environment Officer at the UNSW Environment Collective, a student representative council subordinate responsible for thinking ecologically on behalf of the university’s students. 

“The best solution to anything is a preventative one, and we really can’t afford to let climate change reach boiling point where species are starting to go extinct,” said Chappel. 

However, the effects of climate change aren’t limited only to terrestrial species. Research published in NatureGeosciencereveals that carbon dioxide (CO₂) is being added to the atmosphere at least ten times faster than a major warming event about 50 million years ago. With increasing CO₂levels, temperature and ocean acidification also rise, making it a concern how ecosystems are going to cope under such rapid change. 

Listed as critically endangered on the IUCN Red List, the Hawksbill Sea Turtle (Eretmochelys imbricata) is a species predominantly found in coral reefs throughout the world, including the Great Barrier Reef in Australia. While its biggest threats are wildlife trade and pollution, climate change remains a prominent threat to the turtle. 

Hawksbill Sea Turtle (Image by Andrey Armyagovvia Oceanscape Yachts

“The sex of the turtle is determined by the temperature the egg is developed in, so if you have additional warming, then you will get a preponderance of one sex over another,” said Alex Sen Gupta, oceanographer and professor at the UNSW School of Biological, Earth and Environmental Sciences. “This could have severe implications for populations.” Coral reefs are key habitats with which the Hawksbill are associated, and according to the Sea Turtle Conservancy, increased water temperatures and acidification will undermine the ability of coral polyps to survive and build reefs. 

Coral reefs of the world’s tropical and subtropical regions are habitat to about one quarter of the 500,000 animal species living in the world’s oceans. Providing shelter, spawning grounds and as nutrients to form a rich marine ecosystem, coral reefs serve an important role. Mass coral bleaching triggered by climate change has become a global problem, occurring when unnaturally warmer ocean water destroys the algae of coral reefs, leaving coral to stave. 

“We’re getting higher frequency of bleaching, and because corals take such a long time to grow, if that frequency gets too high, eventually, the coral become untenable,” said Gupta. A study published in Naturereveals that 30% of Great Barrier Reef coral died in a nine-month heatwave throughout 2016. Since then, as of 2018, half of the Great Barrier Reef has died as a result of bleaching. 

Increasing CO₂levels expose coral to major warming and acidification, causing a ripple of effects across the entire ecosystem. “Coral make their shells from calcium carbonate, which is essentially chalk. If you put chalk in acidic water, the chalk melts. Essentially, you have a situation where the shells of the coral are disintegrating at a faster rate than they can grow,” Gupta said.

Climate change is changing the dynamics of most ecosystems on Earth, and if not addressed holistically by world leaders, will continue to ripple its affects across the planet’s biodiversity. “There are big opportunities for people on the individual level to live more sustainably and reduce their personal carbon emissions… people in our society, mainly politicians, can take things more seriously and start to act on it,” said Chappel. 

Animal conservation and climate change prevention should no longer be merely a special interest, but a human interest if we want to keep the Earth’s ecosystems from collapse.