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https://www.sciencedaily.com/releases/2017/09/170920182116.htm


170920182116_1_540x360.jpg
Coral bleaching.
Credit: © Richard Carey / Fotolia
 
 

In the past 540 million years, the Earth has endured five mass extinction events, each involving processes that upended the normal cycling of carbon through the atmosphere and oceans. These globally fatal perturbations in carbon each unfolded over thousands to millions of years, and are coincident with the widespread extermination of marine species around the world.

The question for many scientists is whether the carbon cycle is now experiencing a significant jolt that could tip the planet toward a sixth mass extinction. In the modern era, carbon dioxide emissions have risen steadily since the 19th century, but deciphering whether this recent spike in carbon could lead to mass extinction has been challenging. That's mainly because it's difficult to relate ancient carbon anomalies, occurring over thousands to millions of years, to today's disruptions, which have taken place over just a little more than a century.

Now Daniel Rothman, professor of geophysics in the MIT Department of Earth, Atmospheric and Planetary Sciences and co-director of MIT's Lorenz Center, has analyzed significant changes in the carbon cycle over the last 540 million years, including the five mass extinction events. He has identified "thresholds of catastrophe" in the carbon cycle that, if exceeded, would lead to an unstable environment, and ultimately, mass extinction.

In a paper published in Science Advances, he proposes that mass extinction occurs if one of two thresholds are crossed: For changes in the carbon cycle that occur over long timescales, extinctions will follow if those changes occur at rates faster than global ecosystems can adapt. For carbon perturbations that take place over shorter timescales, the pace of carbon-cycle changes will not matter; instead, the size or magnitude of the change will determine the likelihood of an extinction event.

Taking this reasoning forward in time, Rothman predicts that, given the recent rise in carbon dioxide emissions over a relatively short timescale, a sixth extinction will depend on whether a critical amount of carbon is added to the oceans. That amount, he calculates, is about 310 gigatons, which he estimates to be roughly equivalent to the amount of carbon that human activities will have added to the world's oceans by the year 2100.

Does this mean that mass extinction will soon follow at the turn of the century? Rothman says it would take some time -- about 10,000 years -- for such ecological disasters to play out. However, he says that by 2100 the world may have tipped into "unknown territory."

"This is not saying that disaster occurs the next day," Rothman says. "It's saying that, 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. In the geologic past, this type of behavior is associated with mass extinction."

History follows theory

Rothman had previously done work on the end-Permian extinction, the most severe extinction in Earth's history, in which a massive pulse of carbon through the Earth's system was involved in wiping out more than 95 percent of marine species worldwide. Since then, conversations with colleagues spurred him to consider the likelihood of a sixth extinction, raising an essential question:

"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?" Rothman says. "So I sat down one summer day and tried to think about how one might go about this systematically."

He eventually derived a simple mathematical formula based on basic physical principles that relates the critical rate and magnitude of change in the carbon cycle to the timescale that separates fast from slow change. He hypothesized that this formula should predict whether mass extinction, or some other sort of global catastrophe, should occur.

Rothman then asked whether history followed his hypothesis. By searching through hundreds of published geochemistry papers, he identified 31 events in the last 542 million years in which a significant change occurred in Earth's carbon cycle. For each event, including the five mass extinctions, Rothman noted the change in carbon, expressed in the geochemical record as a change in the relative abundance of two isotopes, carbon-12 and carbon-13. He also noted the duration of time over which the changes occurred.

He then devised a mathematical transformation to convert these quantities into the total mass of carbon that was added to the oceans during each event. Finally, he plotted both the mass and timescale of each event.

"It became evident that there was a characteristic rate of change that the system basically didn't like to go past," Rothman says.

In other words, he observed a common threshold that most of the 31 events appeared to stay under. While these events involved significant changes in carbon, they were relatively benign -- not enough to destabilize the system toward catastrophe. In contrast, four of the five mass extinction events lay over the threshold, with the most severe end-Permian extinction being the farthest over the line.

"Then it became a question of figuring out what it meant," Rothman says.

A hidden leak

Upon further analysis, Rothman found that the critical rate for catastrophe is related to a hidden process within the Earth's natural carbon cycle. The cycle is essentially a loop between photosynthesis and respiration. Normally, there is a "leak" in the cycle, in which a small amount of organic carbon sinks to the ocean bottom and, over time, is buried as sediment and sequestered from the rest of the carbon cycle.

Rothman found that the critical rate was equivalent to the rate of excess production of carbon dioxide that would result from plugging the leak. Any additional carbon dioxide injected into the cycle could not be described by the loop itself. One or more other processes would instead have taken the carbon cycle into unstable territory.

He then determined that the critical rate applies only beyond the timescale at which the marine carbon cycle can re-establish its equilibrium after it is disturbed. Today, this timescale is about 10,000 years. For much shorter events, the critical threshold is no longer tied to the rate at which carbon is added to the oceans but instead to the carbon's total mass. Both scenarios would leave an excess of carbon circulating through the oceans and atmosphere, likely resulting in global warming and ocean acidification.

The century's the limit

From the critical rate and the equilibrium timescale, Rothman calculated the critical mass of carbon for the modern day to be about 310 gigatons.

He then compared his prediction to the total amount of carbon added to the Earth's oceans by the year 2100, as projected in the most recent report of the Intergovernmental Panel on Climate Change. The IPCC projections consider four possible pathways for carbon dioxide emissions, ranging from one associated with stringent policies to limit carbon dioxide emissions, to another related to the high range of scenarios with no limitations.

The best-case scenario projects that humans will add 300 gigatons of carbon to the oceans by 2100, while more than 500 gigatons will be added under the worst-case scenario, far exceeding the critical threshold. In all scenarios, Rothman shows that by 2100, the carbon cycle will either be close to or well beyond the threshold for catastrophe.

"There should be ways of pulling back [emissions of carbon dioxide]," Rothman says. "But this work points out reasons why we need to be careful, and it gives more reasons for studying the past to inform the present."

Edited by iCambrian

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Each of us has a minimum time.

Each of us has a maximum time.

Only between these times can we suicide ourselves, l think.

Example, news reports about failed suicide attempts. Such as years ago the man who shot himself several times in the head with a nail gun of spikes. Nails removed at hospital and the only result was a headache ... and some counseling.

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6 hours ago, iCambrian said:

In the past 540 million years, the Earth has endured five mass extinction events, each involving processes that upended the normal cycling of carbon through the atmosphere and oceans. These globally fatal perturbations in carbon each unfolded over thousands to millions of years, and are coincident with the widespread extermination of marine species around the world.

etc.etc.

Here another couple of links confirming your post:


http://www.independent.co.uk/environment/mass-extinction-humans-causing-earth-deaths-end-times-warning-a7765856.html

https://www.nature.com/articles/nature22900.epdf?referrer_access_token=8yux8iuZblQQoIVPzikNi9RgN0jAjWel9jnR3ZoTv0O57QoCJQuad0bisgXvAUD4hxq3uUKpm4u9H0ojRjiRRNpAWJ04H9P9_mR_Qv2UPoNh5--ZWcVN-O8yxupDz5DsyMeIPOQsvkcE_L16u8lPCze7Oy3y2LRIAmR6la1dtYTbGyl_o3pqNvT2ruAG-JHb6zg8EFmkxiy3CB3YYqx1BrDQSBMTlOMDbA7NHtOe5nZl8J7m8lRFdWanFfnVjN-h00HaC47ttNXX9F8jT_BVb22OOop3cHgNhQYUVYHNmc2zAeZmcpQYwcZp7hLAZJA1&tracking_referrer=www.independent.co.uk

 

Reminds me of a Native American saying:

When all the Land is Barren 
and all the Forests are burned
When all the rivers are poisoned
and all the fish taken from the sea
people will realize they cannot eat money.

We do not inherit this earth from our ancestors,
We have it on loan from our grandchildren. 

Hope you are keeping well, all the best.

*


 

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According to one strong theory, one of  the first living things on Earth polluted their atmosphere with so much oxygen that it killed them. So if we upset the carbon cycle and add too much carbon dioxide and methane to our atmosphere, we are just making it habitable for the ones who will come next. 

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8 hours ago, notme said:

And as far as we know, there is nowhere else to go, just one tiny fragile planet in our entire vast solar system has shown the ability to support life. 

سبحان الله

قُلْ إِنَّ الْمَوْتَ الَّذِي تَفِرُّونَ مِنْهُ فَإِنَّهُ مُلَاقِيكُمْ ۖ ثُمَّ تُرَدُّونَ إِلَىٰ عَالِمِ الْغَيْبِ وَالشَّهَادَةِ فَيُنَبِّئُكُم بِمَا كُنتُمْ تَعْمَلُونَ

Say: As for the death from which you flee, that will surely overtake you, then you shall be sent back to the Knower of the unseen and the seen, and He will inform you of that which you did.

- Surah al-Jum’uah, Verse 8

Edited by Kazemi

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10 hours ago, AfricanShia said:

Those whom commit suicide are dying before their pre ordained time. 

Could death by pollution be compared to an unintentional suicide? 

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4 hours ago, AfricanShia said:

There is no such thing as an unintentional suicide. Suicide is you willingly killing yourself. 

 

If we polluted, and our pollution were to cause our death or extinction, would this be Gods decision for our end?

Edited by iCambrian

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12 minutes ago, iCambrian said:

 

If we polluted, and our pollution were to cause our death or extinction, would this be Gods decision for our end?

God ordains death for us. We are not destroying the Earth, the Earth is not running out of food, sea levels aren't rising. God is the one who decides the fate of Earth. 

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On 10/3/2017 at 11:29 PM, Gaius I. Caesar said:

Maybe @iCambrian, what do you think?

Well, hypothetically, if people did have free will. And we willingly chose resources that...hypothetically would harm us.  Then I don't see why we would attribute that harm to God's will. Unless God wanted us to harm ourselves, and made us with a mindset that we would do so.

On the article itself though, I think that, there has been billions of years worth of life before that has existed us. The vast majority, some 99% of such, has gone extinct. So, I'm not sure that we (mankind) are invincible. And, As the article points out, one thing that can make or break life on this planet, has been the earths environment.  Yes, an asteroid may have played a role in altering the environment and destroying the dinosaurs, but that extinction event is just one of a handful. Beyond that, the planet has spent hundreds of millions of years, or even billions as an uninhabitable rock. Who says that mankind isn't capable of turning it back into one? Be it intentionally or unintentionally, beyond Gods will? If any species could alter the environment in a way which would destroy us, it would be ourselves. 

Mankind i think though has a bad habit of waiting until things become a problem, before we respond.  California for example, is gradually running out of water. And they are taking precaution to lessen their water use, which is good. But, did they really need to wait until their aquifer was drying up before they began responding? And even now, they haven't solved their issue. It's as if people need to run out of water before they realize that it is not an infinite resource, or that adjustments need to be made to our actions. Regarding earth, perhaps the environment needs to hurt us, before we respond in correcting our actions.

But with earth you get positive and negative feedback cycles, and global extinction with change in the environment. Is the earths environment really something we want to mess around with? And even if changes occurred over thousands of years, someone will have to live with these changes and will have to respond to events caused by our actions.

Just some thoughts...

 

What do you think?

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13 minutes ago, iCambrian said:

Well, hypothetically, if people did have free will. And we willingly chose resources that...hypothetically would harm us.  Then I don't see why we would attribute that harm to God's will. Unless God wanted us to harm ourselves, and made us with a mindset that we would do so.

In Islam, Allah سُبْحَانَهُ وَ تَعَالَى is not attributed to the harm we cause to ourselves, so although it may look like I am disagreeing, I agree with you.

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On 10/3/2017 at 3:12 PM, notme said:

According to one strong theory, one of  the first living things on Earth polluted their atmosphere with so much oxygen that it killed them. So if we upset the carbon cycle and add too much carbon dioxide and methane to our atmosphere, we are just making it habitable for the ones who will come next. 

what theory is that?

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34 minutes ago, iCambrian said:

what theory is that?

Oh gosh you're asking me to go look stuff up? 

Ok, from memory: something about the first bacteria to photosynthesize. Oxygen is corrosive, and nothing breathed it at first but it was a by product of photosynthesis, which was so successful a life strategy, it contaminated all the air until everything died off or evolved. 

Do you need me to look up the actual details, or is by memory sufficient? 

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13 hours ago, notme said:

Oh gosh you're asking me to go look stuff up? 

Ok, from memory: something about the first bacteria to photosynthesize. Oxygen is corrosive, and nothing breathed it at first but it was a by product of photosynthesis, which was so successful a life strategy, it contaminated all the air until everything died off or evolved. 

Do you need me to look up the actual details, or is by memory sufficient? 

Well, I got the first part with cyanobacteria and banded iron formations. I was just curious regarding the second part, the extinction by oxygen. It's all Precambrian, and I'm not familiar with what fossil evidence or genetics related evidence that is tied in depicting a mass extinction.

I can google it though, unless you have some info to share.

Thanks

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6 minutes ago, iCambrian said:

Well, I got the first part with cyanobacteria and banded iron formations. I was just curious regarding the second part, the extinction by oxygen. It's all Precambrian, and I'm not familiar with what fossil evidence or genetics related evidence that is tied in depicting a mass extinction.

I can google it though, unless you have some info to share.

Thanks

I read it a while back. I don't remember whether it was a book or a MOOC. It wasn't an article or general website, but I'm sure the information is out there. I'll see what I can dig up, since I'll have an idea where to look. 

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3 hours ago, hasanhh said:

^^^^ There is another event when the atmosphere goes through methane poisoning. Release of that frozen stuff under seawater.

When was this? Care to share a source?

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