Researchers proposed that mass extinction occurs if one of two thresholds are crossed.
If Earth's oceans hit a certain carbon threshold, the sixth mass extinction could occur at the end of this century.
While many scientists argue that the sixth mass extinction has already begun, the total number of species that have disappeared from the planet comes nowhere near the most apocalyptic events of the past and the rate of species loss is comparable. Daniel Rothman, a mathematician, studied 31 times when there had been similar significant changes and discovered that four out of five previous mass extinctions took place when "threshold of catastrophe" has passed which led to the destruction of life on Earth.
"The worst took place 252 million years ago and is known as the Great Dying".
"How can you really compare these great events in the geologic past, which occur over such vast timescales, to what's going on today, which is centuries at the longest?" he said.
Researchers from Massachusetts Institute of Technology (MIT) in the United States analysed significant changes in the carbon cycle over the last 540 million years, including the five mass extinction events. The Permian extinction is thought to have been caused by huge magma pulses that belched carbon dioxide into the atmosphere, while the dinosaur-killing K-T event was thanks to an asteroid impact triggering planet-wide wild fires and volcanic eruptions. "But how that process plays out remains unknown", the paper said.
The Independent UK further quoted him saying, "By analyzing 31 carbon isotopic events during the past 542 million years, I identify the critical rate with a limit imposed by mass conservation".
Rothman has derived a mathematical formula that predicts that if the current trend in carbon emissions on Earth continues, the level of oceanic and atmospheric carbon would exceed a hypothetical threshold point by 2100.
For the modern era, the "threshold for catastrophic change" is related to the amount of carbon present rather than its rate of increase.
What It Means If A Mass Extinction Happens In 2100? The trouble was, historical carbon anomalies can take thousands of years to play out, while the clear spike we're seeing today can only be traced back a hundred years or so. The worst-case scenario would result in more than 500 gigatons, the report said.
"This is not saying that disaster occurs the next day", Rothman says. "It's saying that, if left unchecked, the carbon cycle would move into a realm which would be no longer stable, and would behave in a way that would be hard to predict".
That amount, calculated, is about 310 gigatons, which the researchers estimate to be roughly equivalent to the amount of carbon that human activities will have added to the world's oceans by the year 2100.
An analysis of data from the last 540 million years led to researchers at MIT predict the sixth mass extinction.