Prehistoric events such as mass extinctions are difficult to predict because these events continue for a period of thousands of years. However, a new study carried out by researchers at the Massachusetts Institute of Technology (MIT) suggests that humans on Earth might experience the start of a #mass extinction event by the end of 21st century.

Mass extinction events

Earlier scientific studies have indicated the occurrence of five mass extinction events on Earth in the past 540 million years. In each of these events, about three-fourths of the marine species were killed. The most recent event was the Cretaceous-tertiary event that occurred nearly 65.5 million years ago and completely wiped out dinosaurs from Earth.

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Each of the previous five extinction events was also characterized by processes that toppled the normal #Carbon Cycle on Earth.

Daniel Rothman, a professor of geophysics at the MIT says the patterns exhibited in carbon cycle disruptions during previous mass extinctions are similar to those being observed by scientists today. He explains that while there is no fundamental change in carbon cycle on Earth, the carbon cycle disturbance has now become faster. Earlier, such disturbances used to take tens of thousands to millions of years, but now they are occurring at a timescale of centuries.

Rothman’s study proposes that a mass extinction event would occur if any one of the two "thresholds of catastrophe" in carbon cycle is crossed: (1) carbon cycle changes start occurring at a pace much faster than what global ecosystems can adapt or (2) the magnitude of the perturbation becomes too large (even if these perturbations are occurring over shorter timescales).

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Current trends of carbon emissions are likely to disturb carbon cycle

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. By that time, about 310 gigatons of carbon would have been added to the oceans. This would disturb the carbon cycle and result in a highly unstable environment. Moreover, there are chances that this cycle would also accelerate itself. Rothman’s mathematical formula is based on fundamental physical principles that relate magnitude and rate of perturbations in carbon cycle to the timescale that separates slow changes from the faster ones.

According to Rothman, these findings don’t mean that mass extinction on Earth would start immediately in the year 2100. Such geological events take some time to play out—approximately 10,000 years—although this world might have entered an “unknown territory” by the end of the century if current levels of carbon emissions are left unchecked.

The detailed findings of the study were published in Journal Science Advances. #Dinosaurs