Matt Simon, writing for Wired:

Some 250 million years ago, the organisms of Earth were having a very bad time—the very worst time, you might say. The Permian-Triassic extinction event was unfolding, in which 70 percent of land species and 96 percent of marine species disappeared. Runaway global warming had raised equatorial ocean temperatures to 104 degrees Fahrenheit. The seas rapidly acidified, so shelled critters struggled to build their protective homes. Indeed, the fossil record shows these species got it the worst—strong evidence that the extinction’s culprit was CO2 mucking with the oceans’ pH balance, and the rest of the planet, for that matter. Every decade or so, ozone-eating gases would dissolve Earth’s protective layer in the sky, irradiating plants and animals, before the ozone layer closed up. This happened again and again, allowing periodic blasts of extreme radiation to bombard the planet.

Comparing what happened naturally in Siberia to what’s happening globally now:

But how much degassing, exactly? Elkins-Tanton and her colleagues have calculated that the Siberian eruptions that burned coal and other organic matter could have pumped 6,000 billion tons to 10,000 billion tons of carbon into the atmosphere. “The exact quantity is still hard to pin down directly by geological observations,” says Payne. “A lot of this then is a question of scaling up and making the assumption that what we see in the field is representative, and that’s a perfectly reasonable assumption.” Payne adds that he wouldn’t be surprised if the high-end figure of 10,000 billion tons of carbon is in fact low, once you factor in the potential obliteration of rock like limestone, which sequesters its own carbon.

Now for a bit of scary perspective. According to the Global Carbon Project, a consortium of climate researchers, we humans emit nearly 40 billion tons of CO2 a year, and that’s been increasing reliably by a few percent each year, throwing the Earth’s carbon cycle out of whack. Typically, the CO2 system works like filling up a bathtub with an open drain. Volcanoes and tree-burning wildfires release the gas, some of which enters the atmosphere and decays over time, some of which gets absorbed by the ocean. But we as a species are now pumping way too much extra CO2 into the atmosphere. The faucet is turned up too high, and the drain can’t keep up, so the tub is overflowing. The consequence is rapid global warming.

While what happened in Siberia was on a much larger scale than what man is doing now, it’s clear the consequences are still dire. Extinctions and rising tides are already happening, so hopefully we reverse this course sooner than later.