Mass Extinctions of the Past and Climate Change in the Present:

A reader noted on Monday's column that he or she hadn't hadn’t heard about CO2 from burning coal as a factor in the great Permian die-off: 

I have to say that it is amazing how politics leads to reporters saying things like "scientists almost unanimously agree" comments. Scientists are not a political committee voting on a position or at least they weren't until global warming. Wither the facts support or they don't. The truth is a majority of scientific reports now support the theory that a vast volcanic eruption in India destroyed the environment world wide and the asteroid simply killed off the last surviving dinos. The Permian extinction was caused by the Siberian Trapps volcanic eruption that covered most of Siberia in thousands of feet of lava. Any coal fires that existed were meaningless. Global warming due to CO2 was an ant hill compared to the Mt Everest of the volcanic eruptions. That we know and this is the first I ever heard of coal fires at that time.

Hmm. I'm not sure what's wrong with reporting a scientific consensus where it exists. There are informed people who disagree with the asteroid idea, but they are in the minority.

I would highly recommend the book “Under a Green Sky” by Peter Ward, for an interesting perspective on mass extinctions and what they tell us about our current climate situation.

Last year I interviewed Peter Ward and another interesting researcher, Lee Kump, for a column about some new work on the end Permian event, CO2, and, yes, burning coal:

New research published this month reinforces the view that this event, called the End of Permian - or "Mother of all Extinctions" - was set off not by an asteroid impact but by an internal disturbance that released a burst of carbon dioxide into the atmosphere and heated the planet.
It's not the heat itself but the resulting reordering of the living world that would cause a massive die-off, said Pennsylvania State University geoscience professor Lee Kump. Natural selection proceeds. Life extinguishes other life.

According to a theory that Kump proposed several years ago to explain the Mother of all Extinctions, excess heat hinders oxygen from dissolving into the oceans. Oxygen-starved oceans become hostile to fish, plankton, and other familiar life, but friendly to sulfur-using bacteria. They poison other species by exhaling hydrogen sulfide.

Peter Ward, a professor of biology and earth and space sciences at the University of Washington, popularized Kump's theory in his 2007 book Under a Green Sky: Global Warming, the Mass Extinctions of the Past, and What They Can Tell Us About Our Future.
In his vivid visualization: "Most of the shoreline is encrusted with rotting organic matter. Silklike swaths of bacterial slick now putrefying under the blazing sun, while in the nearby shallows mounds of similar mats can be seen growing up toward the sea's surface. . . . From shore to the horizon, there is but an unending purple color - a vast, flat, oily purple, not looking at all like water . . . no fish break its surface, no birds of any kind . . . we are under a pale green sky and it has the smell of death and poison."

Is this our future? Kump says there's no way to know, but the rise in carbon dioxide that triggered the end-Permian is comparable to modern projections if we do nothing to curtail use of fossil fuels worldwide over the next century or so.
The full effect will not appear immediately. On the other hand, it is not out of the question that such a hostile takeover could have started by 3978, the fictional year those lost movie astronauts found their planet overtaken by other apes.

Ward says the view of the end-Permian as a global-warming event represents a shift in thinking from the 1990s, when he and scientists suspected it was triggered by an asteroid. The evidence was overwhelming by then that a space rock had killed off the dinosaurs 65 million years ago. This event was one of five major mass extinctions seen in the fossil record, he said, and it seemed reasonable that a similar cause triggered some of the other four. Now, Ward says, the most widely accepted explanation for the end-Permian is that a confluence of volcanic eruptions and the ignition of enormous beds of coal liberated tons of atmospheric carbon, setting off a chain of events.
The resulting devastation illustrates "the fragility of our biosphere," said Douglas Erwin, a paleobiologist at the Smithsonian Institution and one of the authors of a paper on the end-Permian recently published in Science. "You can wipe out roughly 90 percent of everything in the oceans in 100,000 years without an impact," he said.