Environmental, Health and Safety

Is a Sixth 'Mass Extinction' on the Way?

21 September 2017

Source: CC0 Creative CommonsSource: CC0 Creative Commons

Here’s the kind of news you don’t want to hear: A mathematical analysis of significant changes in the carbon cycle over the last 540 million years points to a mass extermination of species in future millennia.

So far, the Earth has endured five “mass extinction” events, each of which involved processes that disturbed the normal cycling of carbon through the atmosphere and oceans.

Whether or not the uptick in carbon dioxide emissions—which have risen steadily since the 19th century—could tip the planet toward a sixth mass extinction has been difficult to determine. The main reason is that ancient carbon anomalies unfolded over thousands to millions of years, whereas today’s disruption has taken place over just a little more than a single century.

But Daniel Rothman, an MIT professor of geophysics and co-director of the Lorenz Center, a climate think-tank, has analyzed significant carbon cycle changes over the last 540 million years and identified “thresholds of catastrophe.” As published in Science Advances, Rothman proposes that mass extinction occurs if one of two thresholds are crossed. For changes that occur over long timescales, extinctions will follow if changes occur faster than ecosystems can adapt. For those taking place over shorter timescales, the pace becomes irrelevant; instead, the likelihood of extinction will be based on the magnitude of the change.

Given the recent rise in carbon dioxide emissions over a relatively short timescale, Rothman predicts that a sixth extinction will depend on whether a critical amount of carbon—which he calculates at approximately 310 gigatons—is added to the oceans. Taking into account the most recent report of the Intergovernmental Panel on Climate Change, he estimates that we will reach that amount by the year 2100.

Of course, this would take some time to play out—according to Rothman, around 10,000 years. But by 2100, the world may have tipped into what he calls “unknown territory.”

“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,” he says. “In the geologic past, this type of behavior is associated with mass extinction.”

To contact the author of this article, email tony.pallone@ieeeglobalspec.com


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Discussion – 7 comments

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Re: Is a Sixth 'Mass Extinction' on the Way?
#1
2017-Sep-21 3:26 PM

Yep, just a itchy-finger away on the big red button.

Re: Is a Sixth 'Mass Extinction' on the Way?
#2
2017-Sep-22 6:21 AM

And yet all geological and fossil records show that during the Carboniferous period (~4000+ PPM CO2 levels and literally named for the huge abundance of carbon that was in play at the time) the planet was more biologically diverse and plentiful than it had or has ever been.

By those standards we are dangerously low on carbon and CO2 and living in a cool biologically brown and stunted, not lush and green, time.

Re: Is a Sixth 'Mass Extinction' on the Way?
#3
2017-Sep-22 9:10 AM

i thought that meteorites were the causes for mass extinctions of the past. big meteorite hits earth, kicks up lots of dust, causes tectonic plates to move causing pressure on magma which in turn more volcanic eruptions, causing lots of gas-dust-smoke (burning vegetation from magma). all this causes nuke winter which kills vegetation and animals soon follow.

so now your telling me that this will somehow all happen with an uptick of more plant food? please explain without giving me a website to send money to pay for the energy bill to Al Gore's 10,000 sq ft. mansion.

Re: Is a Sixth 'Mass Extinction' on the Way?
#4
2017-Sep-22 10:52 AM

Bull crap is composed largely of carbon. So is Prof Rothman. Is there a strong correlation?

Re: Is a Sixth 'Mass Extinction' on the Way?
#5
2017-Sep-22 12:58 PM

The carboniferous period had very high oxygen levels (animals were larger, the few amphibians and arthropods that were), as well; global temperatures were higher, the atmosphere was thicker, winds were stronger... it wasn't just high carbon and biodiversity...

Most mass extinctions are caused by climate change-- either by CO2 Overturning Pulses in a Stratified ocean (from induced thermobaric instability), Anoxia in a Stratified Ocean, or Acidfication. Even so, these events release 0.2 gigatonnes per year, whereas anthropogenic addition is over 10 gigatonnes per year.

Otherwise, abnormal volcanic activity takes the cake on mass extinction.

Get your head in the game, dudes.

https://xkcd.com/1732/

Re: Is a Sixth 'Mass Extinction' on the Way?
#6
In reply to #5
2017-Sep-22 1:58 PM

Looked at your chart and the only problem is that the right hook at the bottom doesn't appear to be actually happening. .6 deg C drop since last year and ice inventory in the arctic increasing according to NASA.

Re: Is a Sixth 'Mass Extinction' on the Way?
#7
2017-Sep-22 3:03 PM

We can only hope it will put us out of our misery.

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