Among the many mechanisms by which humans have pushed animals to extinction, warming the planet may often have been a contributing factor. However, this is the first time that human-induced global warming, and the sea level rise that comes with it, has been identified as the primary reason for a mammal's demise.
The mosaic-tailed rat (Melomys rubicola) was always a highly vulnerable species; when first recorded in 1845, it was restricted to a 340 by 150-meter (1,100 by 500 feet) coral island called Bramble Cay. With such a tiny range, survival chances were always slim. The arrival of a competitor or changes to vegetation could easily have seen the rat joining the dodo and Tasmanian tiger. Nevertheless, reports from the 70s and 80s suggest the animals were then quite numerous.
However, it is the cause of M. rubicola's extinction that is likely to ensure the obscure rat's place in history. A report concludes that Bramble Cay has been repeatedly inundated in recent years as a consequence of rising seas, and that it is for this reason that the rat has not been seen since 2009, and is now almost certainly extinct.
Bramble Cay lies in the Torres Strait between Australia and New Guinea, and is seldom visited by humans. In August and September 2014, researchers from the University of Queensland placed small mammal traps – baited with rolled oats, peanut butter, and golden syrup – and camera traps throughout the island in the hope of finding some signs of the nocturnal mammal. Empty-handed, the researchers interviewed a fisherman who sometimes stops at the island. He said he had not seen the rat since 2009.