Researchers warn that more than 500 species of land animals — including the Sumatran rhino and the Española tortoise — are on the brink of extinction and will likely be lost within two decades, The Guardian reports. Land vertebrates with fewer than 1,000 individuals left were considered at risk of dying out in the near future in the new analysis published in the journal Proceedings of National Academy of Scientists.
The researchers also said because 84 percent of those species lived in the same regions their demise could create a domino effect. For example, per The Guardian, overhunting of sea otters led to the extinction of of the Steller's sea cow in the 1700s because otters were the main predator of kelp-eating sea urchings. When left unchecked, the sea urchins devastated the kelp forests upon which the sea cows grazed. "Extinctions breed extinctions," the researchers said.
Of course, a decline in biodiversity will have adverse effects for humans, as well. "When humanity exterminates other creatures, it is sawing off the limb on which it is sitting, destroying working parts of our own life-support system," said Stanford University's Paul Ehrlich, one of the researchers. "The conservation of endangered species should be elevated to a global emergency for governments and institutions, equal to the climate disruption to which it is linked."
University College London's Georgina Mace said she wasn't convinced that simply having fewer than 1,000 individuals was the best way to measure a species' extinction risk — a declining trend for the population is crucial, too — but, nevertheless, she believes the study "re-emphasizes some startling facts" and that "action is important for many reasons." Read more at The Guardian.Tim O'Donnell