Author Topic: New Study Shows Breaching Carbon Threshold Could Lead to Mass Extinction  (Read 794 times)

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Offline Elderberry

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SciTechDaily by Jennifer Chu 7/17/2019

When carbon emissions pass a critical threshold, it can trigger a spike-like reflex in the carbon cycle, in the form of severe ocean acidification that lasts for 10,000 years, according to a new MIT study.

In the brain, when neurons fire off electrical signals to their neighbors, this happens through an “all-or-none” response. The signal only happens once conditions in the cell breach a certain threshold.

Now an MIT researcher has observed a similar phenomenon in a completely different system: Earth’s carbon cycle.

Daniel Rothman, professor of geophysics and co-director of the Lorenz Center in MIT’s Department of Earth, Atmospheric and Planetary Sciences, has found that when the rate at which carbon dioxide enters the oceans pushes past a certain threshold — whether as the result of a sudden burst or a slow, steady influx — the Earth may respond with a runaway cascade of chemical feedbacks, leading to extreme ocean acidification that dramatically amplifies the effects of the original trigger.

This global reflex causes huge changes in the amount of carbon contained in the Earth’s oceans, and geologists can see evidence of these changes in layers of sediments preserved over hundreds of millions of years.

Rothman looked through these geologic records and observed that over the last 540 million years, the ocean’s store of carbon changed abruptly, then recovered, dozens of times in a fashion similar to the abrupt nature of a neuron spike. This “excitation” of the carbon cycle occurred most dramatically near the time of four of the five great mass extinctions in Earth’s history.

Scientists have attributed various triggers to these events, and they have assumed that the changes in ocean carbon that followed were proportional to the initial trigger — for instance, the smaller the trigger, the smaller the environmental fallout.

But Rothman says that’s not the case. It didn’t matter what initially caused the events; for roughly half the disruptions in his database, once they were set in motion, the rate at which carbon increased was essentially the same. Their characteristic rate is likely a property of the carbon cycle itself — not the triggers, because different triggers would operate at different rates.

What does this all have to do with our modern-day climate? Today’s oceans are absorbing carbon about an order of magnitude faster than the worst case in the geologic record — the end-Permian extinction. But humans have only been pumping carbon dioxide into the atmosphere for hundreds of years, versus the tens of thousands of years or more that it took for volcanic eruptions or other disturbances to trigger the great environmental disruptions of the past. Might the modern increase of carbon be too brief to excite a major disruption?

More: https://scitechdaily.com/new-study-shows-breaching-carbon-threshold-could-lead-to-mass-extinction/
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Offline Hoodat

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Warmer temperatures mean less carbon dioxide in the oceans.  Henry's Law.
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Offline Elderberry

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Don't confuse them with any facts now. Its feelings that are most important, don't you know?
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Offline Joe Wooten

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Warmer temperatures mean less carbon dioxide in the oceans.  Henry's Law.

I was about to say that too. You need a lot of sulfur dioxides to acidify the ocean...

Offline dfwgator

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And monkeys COULD fly out of my butt.

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I was about to say that too. You need a lot of sulfur dioxides to acidify the ocean...

Why would one need sulfur dioxides to acidify the ocean?

Online rustynail

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If President Obama had given us a Carbon Tax none of this would be of concern.

Offline IsailedawayfromFR

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  • Sept 11 2001 or March 6 1836
This appears as nothing more than propping up his 2017 prediction that we will be extinct at the end of the century

In 2017, Rothman made a dire prediction: By the end of this century, the planet is likely to reach a critical threshold, based on the rapid rate at which humans are adding carbon dioxide to the atmosphere. When we cross that threshold, we are likely to set in motion a freight train of consequences, potentially culminating in the Earth’s sixth mass extinction.
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