Guy McPherson is a professor emeritus of evolutionary biology, natural resources and ecology at the University of Arizona, and has been a climate change expert for 30 years. He has also become a controversial figure, due to the fact that he does not shy away from talking about the possibility of near-term human extinction.
While McPherson's perspective might sound like the stuff of science fiction, there is historical precedent for his predictions. Fifty-five million years ago, a 5-degree Celsius rise in average global temperatures seems to have occurred in just 13 years, according to a study published in the October 2013 issue of the Proceedings of the National Academy of Sciences. A report in the August 2013 issue of Science revealed that in the near term, earth's climate will change 10 times faster than during any other moment in the last 65 million years.
Prior to that, the Permian mass extinction that occurred 250 million years ago, also known as the “Great Dying,” was triggered by a massive lava flow in an area of Siberia that led to an increase in global temperatures of 6 degrees Celsius. That, in turn, caused the melting of frozen methane deposits under the seas. Released into the atmosphere, those gases caused temperatures to skyrocket further. All of this occurred over a period of approximately 80,000 years. The change in climate is thought to be the key to what caused the extinction of most species on the planet. In that extinction episode, it is estimated that 95 percent of all species were wiped out.
Today's current scientific and observable evidence strongly suggests we are in the midst of the same process – only this time it is anthropogenic, and happening exponentially faster than even the Permian mass extinction did.
In fact, a recently published study in Science Advances states, unequivocally, that the planet has officially entered its sixth mass extinction event. The study shows that species are already being killed off at rates much faster than they were during the other five extinction events, and warns ominously that humans could very likely be among the first wave of species to go extinct.
So if some feel that McPherson's thinking is extreme, when the myriad scientific reports he cites to back his claims are looked at squarely and the dots are connected, the perceived extremism begins to dissolve into a possible, or even likely, reality.
The idea of possible human extinction, coming not just from McPherson but a growing number of scientists (as well as the aforementioned recently published report in Science), is now beginning to occasionally find its way into mainstream consciousness.
Source: Mass Extinction: It's the End of the World as We Know It