Scientists think they have discovered the falling domino that has led to the largest mass extinction of the Earth, and fears that man-made climate change will bring the planet to a vaguely similar path.
Approximately 250 million years ago, about 90 percent of marine life and 70 percent of the earth life in the so-called "Great Dying" disappeared.
Scientists have long speculated that massive volcanic eruptions have caused a cataclysmic event, but how it worked was a little unclear.
It was not the lava itself. A new study in Science on Thursday used a comprehensive computer simulation to plot what happened after volcanoes exploded: they led to an increase in ocean temperatures of around 11 degrees Celsius, which then exhausted seawater oxygen.
This hot oxygen level caused the accumulation of seas, especially from the equator.
After the volcano erupted, the carbon dioxide level was more than 12 times higher than today, said study director Justin Penn, a scientist at Earth Sciences at Washington University.
The water loses oxygen when it gets warm, just like a warm roll of cola melts, said Mr. Penn.
Scientists looked at dozens of modern species to see what had happened to them in warmer, oxygenated water, and that helped them understand the extinction of the past.
One key in the research is that more species died away from the equator. This is because tropical species have been more acclimated to low oxygen levels, said Mr. Penn.
While people are not warming the Earth anywhere other than what happened naturally 250 million years ago, "it gives us our future as a category of aspiring real disaster," said study co-author Curtis Deutsch, a scientist on Earth, University of Washington.
Ancient dead "shows almost exactly what lies at the end of the way," said Mr. Deutsch. "We do the same thing with the Earth and ocean climate."
The study predicts that if carbon dioxide emissions capture heat at current levels, by the year 2300, the globe will experience 35 to 50 percent of the level of extinction that has manifested itself in the Great Dying.
Palaeontologist Paul Weigle of the University of Leeds said that no current global warming scenario represents 20 degrees of warming in the next few centuries, so it could be a millennium.
Even an event of 10 percent as bad as Big Dying would be terrible, "said Wignall, who was not part of the study.
Others outside the scientists said the study provides a spooky look at the possible future of Earth.
"Because we are rapidly accelerating on Earth, the results of this study may prove to be very useful in understanding what will happen to life in future oceans," said University Professor David Bottjer in an e-mail.