Scientists have identified the world’s first mammal species to go extinct because of human-driven climate change. The small Australian rodent known as the Bramble Cay melomys (Melomys rubicola) has disappeared from its native island in the Great Barrier Reef.
The rodent was the most isolated of any Australian mammal, for it was only known to have lived on Bramble Cay. That it was the most isolated also made it have an exceedingly restricted range. Sadly, because the melomys’ home isle stands only 10 feet above sea level, the sea rise from climate change adversely reduced the species’ habitat and decimated the mammal’s numbers.
The melomys, also called the mosaic-tailed rat, was last seen in 2009 but has not made an appearance since then. This has prompted scientists to conclude that the humble rodent has now become extinct.
The rats were first reported in 1845 by Europeans on the island. It was considered the only mammal endemic to the Great Barrier Reef region. As of 1978, several hundred melomys still existed.
Scientists theorize the animals first arrived at Bramble Cay via driftwood or sailing vessel. University of Queensland scientist Luke Leung shared, “They may have been marooned on high ground at Bramble Cay. And they were thriving there for a long time, but now they are gone.”
By 1998, the part of the island that sits above high tide shrank from 9.8 acres to just 6.2 acres, which has decreased the island’s vegetation. And, in the span of just 10 years, the melomys experienced a habitat loss of about 97 percent. Vegetation cover on the island likewise declined from 2.2 hectares in 2004 to 0.065 hectares in 2014. Scientific survey counts conducted by Queensland’s Department of Environment and Heritage Protection in partnership with the University of Queensland began to show the species as threatened when, in 1998, only 42 were captured, only 10 in 2002, 12 in 2004, none in 2011, and none again in 2014.
The shrinking habitat on the tiny island meant increased competition for food. Melomys had to contend with nesting seabirds and turtles. In March 2014 it was documented that “the island’s livable habitat – that is, the area above the high-tide mark – was the smallest ever recorded, and refuge sites for the melomys in rock caves, crevices and overhangs had begun to disappear.” By August and September 2014, no melomys tracks nor scat could be found.
Leung revealed, “The key factor responsible for the death of the Bramble Cay melomys is almost certainly high tides and surging seawater, which has traveled inland across the island. The seawater has destroyed the animal’s habitat and food source. This is the first documented extinction of a mammal because of climate change.”
University of California – Berkeley Professor Anthony D. Barnosky confirmed Leung’s conclusions. Barnosky noted that “storm surges and rising seas had wiped out a species that had no route of escape.”
Ian Gynther, who led the scientific team from Queensland’s Department of Environment and Heritage Protection, added: “The key factor responsible for the extirpation of this population was almost certainly ocean inundation of the low-lying cay, very likely on multiple occasions, during the last decade, causing dramatic habitat loss and perhaps also direct mortality of individuals.”
The Queensland team explained further, “For low-lying islands like Bramble Cay, the destructive effects of extreme water levels resulting from severe meteorological events are compounded by the impacts from anthropogenic climate change-drive-sea-level rise.”
When comparing sea levels from 1901 to 2010, evidence shows worldwide sea levels have risen on average by 8 inches, which is an unparalleled rate compared to the last 6000 years. Unfortunately, where the Bramble Cay island is located, sea level has in fact risen almost twice as much as the global average. The loss of the melomys is therefore deemed as the first identified mammal species to have gone into extinction because of the warming climate.
Lee Hannah, a senior scientist with Conservation International remarked, “We knew something had to be first, but this is still stunning news.”
Hannah projects that one in five species is at risk of extinction from climate change. He emphasizes that species on small islands and mountains are the ones most threatened, for they are unlikely to have anywhere else to go once things change.
Hannah laments, “This species could have been saved.” He thereby encourages the reduction of greenhouse gas emissions in an ongoing effort to promote changes in human behavior so that we cultivate better stewardship of the environment. Moreover, Hannah pushes for the design and construction of protected areas to accommodate changing climate so that threatened wildlife can be relocated in time.
Many in the scientific, ecological, and conservation communities are saddened by the loss of the melomys. They warn that our planet is in a crisis of biodiversity loss. Tony Juniper, author of the book What’s Really Happening to Our Planet, for instance, admonishes “how 10,000 years ago 99.9% of the vertebrate biomass of the planet was wild – now the figure is just 4%. We, and the animals grown to feed the meat eaters, make up the other 96%.”
In other words, the extinction of the melomys is only the tip of the iceberg. Ecologist John White, of Australia’s Deakin University, cautions: “I am of absolutely no doubt we will lose species due to the increasing pressures being exerted by climate change. Species restricted to small, low-lying islands or those with very tight environmental requirements are likely to be the first to go.”
On the Center for Biological Diversity’s website, it is clearly stated, “Our planet is now in the midst of its sixth mass extinction of plants and animals – the sixth wave of extinctions in the past half-billion years. We’re currently experiencing the worst spate of species die-offs since the loss of the dinosaurs 65 million years ago… Unlike past mass extinctions, caused by events like asteroid strikes, volcanic eruptions, and natural climate shifts, the current crisis is almost entirely caused by us – humans. In fact, 99 percent of currently threatened species are at risk from human activities, primarily those driving habitat loss…and global warming.”