New Delhi: Courtesy climate change as well as human behaviour towards nature and its beings, the world may need to prepare itself for its sixth mass extinction event, which researchers have said will begin by about 2100.
The reason? The amount of carbon being pumped into the atmosphere.
The threat that the ecosystem is facing due to this, has scientists worried and going by the rate at which the world is losing out on its biodiversity, they say that the possibility of a mass extinction in the future looms larger than ever.
Scientists came to this conclusion after a comprehensive mathematical study of the five previous events in the last 540 million years.
According to a report in the Independent UK, professor Daniel Rothman, co-director of the Massachusetts Institute of Technology’s Lorenz Centre, theorised that disturbances in the natural cycle of carbon through the atmosphere, oceans, plant and animal life played a role in mass die-offs of animals and plants.
After studying such changes based on when they took place 31 times, he found that four out of the five previous mass extinctions occurred when the disruption crossed a “threshold of catastrophic change”.
The 'Great Dying', known as the worst mass extinction of all – that took place 248 million years ago when 96 percent of species died out – breached one of these thresholds by the greatest margin.
Based on his analysis of these mass extinctions, Professor Rothman developed a mathematical formula to help predict how much extra carbon could be added to the oceans – which absorb vast amounts from the atmosphere – before triggering a sixth one.
The answer came as a shock.
For the figure of 310 gigatons is just 10 gigatons above the figure expected to be emitted by 2100 under the best-case scenario forecast by the Intergovernmental Panel on Climate Change. The worst-case scenario would result in more than 500 gigatons, the report said.
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.
Professor Rothman emphasised that dramatic changes to the carbon cycle wasn't a necessary occurrence for a mass extinction to take place – as shown by the absence of this during the Late Devonian extinction more than 360 million years ago.
The study, published in the journal Science Advances, noted that events such as volcanic eruptions, climate change and other environmental factors could also play a role.
Does this mean that mass extinction will soon follow at the turn of the century? As per a report in Phys.org, Rothman says it would take some time—about 10,000 years—for such ecological disasters to play out. However, he says that by 2100 the world may have tipped into "unknown territory."
"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 difficult to predict. In the geologic past, this type of behavior is associated with mass extinction."
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.
“The modern critical size for the marine carbon cycle is roughly similar to the mass of carbon that human activities will likely have added to the oceans by the year 2100.”