- 25 Sep 2017 19:22
#14846398
Unlike the comet striking the Yucatan, this will likely be a slow-motion (at least in human terms) mass extinction.
http://www.newsweek.com/meade-prophecy- ... sor-669892
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. It's a homeostatic system that is able to absorb a lot of changes in its input factors and remain stable...but there are limits.
Rothman noted that every previous mass extinction event was preceded by a disruption in the carbon cycle. The problem with this indicator, however, is that not every disruption in the carbon cycle led to an extinction event. Rothman's study was designed to separate what carbon cycle disruptions that lead to extinctions from those that don't. The object, of course, is a more robust indicator for predicting mass extinction events.
He hypothesized that the rate of change of carbon addition was the differentiating factor. If true, then a mass extinction event would be triggered by 1) adding a threshold amount of carbon, and 2) doing so in a short amount of time. So there would be two actual trigger thresholds to pass: absolute amounts of carbon, and rate of change of carbon addition.
Using the formula he developed by backtesting against historical data, he concluded that 310 extra gigatons of carbon in the oceans by 2100 would be a valid trigger.
He also noted that it would take a period of 10,000 years for all these changes to unwind fully. It's unclear if this process can be reversed, once it is triggered.
http://www.newsweek.com/meade-prophecy- ... sor-669892
Daniel Rothman, a geophysict at the Massachusetts Institute of Technology, compiled a database of information about previous mass extinctions and major environmental changes. After analyzing the data, he boiled it down to a (deceptively) simple equation and a number: the amount of carbon that would be required—if added over a short period of time—to throw the carbon cycle out of whack.
That threshold is about 310 gigatons of extra carbon in the oceans. Earth will likely hit that critical amount by 2100...
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. It's a homeostatic system that is able to absorb a lot of changes in its input factors and remain stable...but there are limits.
Rothman noted that every previous mass extinction event was preceded by a disruption in the carbon cycle. The problem with this indicator, however, is that not every disruption in the carbon cycle led to an extinction event. Rothman's study was designed to separate what carbon cycle disruptions that lead to extinctions from those that don't. The object, of course, is a more robust indicator for predicting mass extinction events.
He hypothesized that the rate of change of carbon addition was the differentiating factor. If true, then a mass extinction event would be triggered by 1) adding a threshold amount of carbon, and 2) doing so in a short amount of time. So there would be two actual trigger thresholds to pass: absolute amounts of carbon, and rate of change of carbon addition.
Using the formula he developed by backtesting against historical data, he concluded that 310 extra gigatons of carbon in the oceans by 2100 would be a valid trigger.
There are some major caveats to the paper. The paper doesn't identify any mechanisms for how reaching that threshold would lead to a mass extinction event; the carbon cycle could just be a related indicator, not a cause, of a mass extinction. And the data came from records gathered from many other sources, which introduces some imperfections and forms of bias.
He also noted that it would take a period of 10,000 years for all these changes to unwind fully. It's unclear if this process can be reversed, once it is triggered.
The old world is dying, and the new world struggles to be born: now is the time of monsters. -Antonio Gramsci