Anthropogenic Global Warming and the Great Dying

New research puts current human forced climate change in the same context as some of the worst extinction events in the geological record including the End Permian Extinction.

The Permian Mass Extinction 251.9 million years ago, otherwise known as “The Great Dying," was the closest this planet has come to extinguishing all complex life on Earth. Around 90% of all species died out in this single event, a worse toll even than the Cretaceous extinction that wiped out the dinosaurs. For years the cause of the Permian Mass Extinction has been linked to massive volcanic eruptions in Siberia. Volcanic CO2 and a cocktail of noxious gasses combined with burning coal and geothermally-baked methane emissions to enact a combination of toxic effects and, most importantly, ocean acidification and global warming. It led to a world where equatorial regions and the tropics were too hot for complex life to survive. That’s a fact so astonishing it bears repeating: global warming led to a large portion of planet Earth being lethally hot on land and in the oceans! The cascading extinctions in ecosystems across the planet unfolded over 61,000 years, and it took 10 million years for the planet to recover! For comparison, our distant ancestors separated from apes only 7 million years ago. Until recently the scale of the Permian Mass Extinction was seen as just too massive, its duration far too long, and dating too imprecise for a sensible comparison to be made with today’s climate change. No longer.
Burgess et al’s paper brings the Permian into line with many other global-warming extinction events, like the Triassic, the Toarcian, the Cretaceous Ocean Anoxic Events, The PETM, and the Columbia River Basalts, whose time frames have been progressively reduced as more sophisticated dating has been applied to them. They all produced the same symptoms as today’s climate change – rapid global warming, ocean acidification, and sea level rises, together with oxygen-less ocean dead zones and extinctions. They were all (possibly excluding the PETM - see below) triggered by rare volcanic outpourings called “Large Igneous Provinces," (LIPs) that emitted massive volumes of CO2 and methane at rates comparable to today’s emissions. The PETM may also have been triggered by a LIP, although that is still debated. Can we seriously expect Earth’s climate to behave differently today than it did at all those times in the past?

Don’t overlook CO2’s other impact.

You might well wonder what the problem is with ocean acidification. After all, though the ocean’s pH is dropping, it’s still alkaline after that drop, and to actually turn it acidic (below pH 7, remember) would require a colossal amount of carbon dioxide in the atmosphere – far more than there is currently or even will be 100 years into the future. It’s a concern that the pH is dropping, sure, but is there really any consequence? Sadly, the answer is yes. The direct effects of ocean acidification may not be immediately felt by humans, but unsurprisingly by the organisms that inhabit the ocean. And effects on them could have knock on effects that impact our lives too. One of the groups of animals most affected by ocean acidification will be calcifying organisms. These are animals such as clams, oysters, and crustaceans that pull carbonate ions from seawater to form the calcium carbonate that makes up their shells. This is possible because calcium carbonate is supersaturated in ocean surface waters, meaning the calcifying organisms are able to precipitate it out as solid calcium carbonate under the right conditions. The problem lies in some of the other chemistry that carbonate ions can undergo in seawater. ...
Good article with lots of references to studies and other stories.

Seattle Times did an excellent series a couple years back

Sea Change - Vital Part of Food Web Dissolving