The ongoing Holocene extinction is often referred to as the Earth's potential sixth mass extinction, but a new study claims it would actually be the seventh if that prediction comes to fruition.
Authors of the study, published Wednesday in Science Advances, suggests the Carnian Pluvial Episode, a mysterious time of sudden climate and environmental change in the Late Triassic some 233 million, was "clearly a mass extinction," adding to the "big five" over the past 500 million years that have already been recorded. A team of scientists reviewed geological evidence and the fossil record, The Guardian reports, coming to the conclusion that enormous volcanic eruptions occurred at the same time as a global loss of plants and animals.
One of the scientists who worked on the project, Jacopo Dal Corso, said there is evidence the volcanic explosions pumped vast amounts of greenhouse gas into the air, which drove global warming and ultimately harmed much of the Earth's biosphere, although dinosaurs during that time spread out widely and became the dominant terrestrial vertebrates for reasons that still aren't clear. The paper says modern coral reefs and other recognizable ecosystems also formed in the aftermath.
Stephen Brusatte, a paleontologist at the University of Edinburgh who wasn't involved with the research, was impressed with the study and said the researchers "have set out an ambitious agenda for testing this big, bold idea that dinosaur diversification was triggered by climate and environmental change," but he also acknowledged more needs to be done to see if the two events are really linked. Still, he said, "I think the odds are good." Read more at The Guardian. Tim O'Donnell
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