Humans could be heading into a chain of events that could lead to Earth's next mass extinction, according to one scientist's calculations.
Daniel Rothman, a geophysicist from the Massachusetts Institute of Technology, says he has identified "thresholds of catastrophe" in the carbon cycle that, if exceeded, would cause the environment to be unstable, eventually leading to mass extinction.
How did he arrive at this conclusion? Well, Rothman looked at and analyzed major changes in the carbon cycle over the last 540 million years, including the five past mass extinction events that happened on Earth.
Carbon Cycle
In his paper, published in Science Advances, he begins by proposing that all mass extinctions could be characterized as a significant change in Earth's carbon cycle, but there was the matter of timescale. If previous mass extinctions stretched over long periods — think up to millions of years — he wanted to determine how long it would take before another one occurs.
"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.
He started by grouping events into two: either short- and long-occurring ones that changed the carbon cycle. Then he scoured through a plethora of geochemical studies to find instances where major disruptions occurred in our planet's carbon cycle.
Ultimately, Rothman arrived at 31 events, which satisfied his criteria, the five mass extinctions included. Then came a big challenge: how was he going to separate extinction events and carbon cycle changes that weren't disruptive or catastrophic?
Threshold
Rothman created a formula able to measure the total carbon mass added to Earth's oceans for each carbon cycle-shifting event. Ultimately, Rothman saw that a certain threshold needed to be crossed.
Reading Rothman's study is a math and geophysics nerd's dream, and his paper goes into far more detail, so go ahead and view it for optimum clarity. But ultimately, he concludes that carbon changes cross the threshold if it occurred faster than the Earth's ability to adapt.
But why does that suddenly mean a mass extinction will happen in 2100? Well, it's tricky. Rothman says our current conditions will lead to crossing the threshold suppose the carbon amount in Earth's oceans hits 310 gigatons.
What It Means If A Mass Extinction Happens In 2100?
So does that mean the world will end in 2100? Not exactly. In Rothman's calculations, a mass extinction may indeed occur by 2100, but actual ecological disasters might take 10,000 years to pan out. However, he says that by 2100, it's possible Earth will have entered "unknown territory."
So no, don't expect dramatic apocalypse-like events in 2100. Rothman is simply saying that Earth's carbon cycle would move into a territory where it's no longer stable, and in turn, the planet would behave in ways that are extremely difficult to predict.
"In the geologic past, this type of behavior is associated with mass extinction."
