Tropical collapse caused by lethal heat: Extreme temperatures blamed for 'dead zone'

Oct 18, 2012
A paleogeographic reconstruction of the Early Triassic world (Smithian substage) around 252-247 million years ago, showing a ‘dead zone’ in the tropics. Marine reptiles (ichthyosaurs), terrestrial tetrapods and fish almost exclusively occurred in higher latitudes (>30 °N and >40 °S) with rare exceptions. Credit: Yadong Sun, University of Leeds

Scientists have discovered why the 'broken world' following the worst extinction of all time lasted so long – it was simply too hot to survive.

The end-, which occurred around 250 million years ago in the pre-dinosaur era, wiped out nearly all the world's species. Typically, a mass extinction is followed by a 'dead zone' during which new species are not seen for tens of thousands of years. In this case, the dead zone, during the Early which followed, lasted for a perplexingly long period: five million years.

A study jointly led by the University of Leeds and China University of Geosciences (Wuhan), in collaboration with the University of Erlangen-Nurnburg (Germany), shows the cause of this lengthy devastation was a temperature rise to lethal levels in the tropics: around 50-60°C on land, and 40°C at the sea-surface.

Lead author Yadong Sun, who is based in Leeds while completing a joint PhD in geology, says: "Global warming has long been linked to the end-Permian mass extinction, but this study is the first to show kept life from re-starting in Equatorial latitudes for millions of years."

Scanning electron microscope image that shows an Early Triassic conodont, a fossil from an eel-like marine animal, that is used for oxygen isotope measurement and past temperature reconstruction. Credit: Yadong Sun

It is also the first study to show close to the ocean's surface can reach 40°C – a near-lethal value at which marine life dies and photosynthesis stops. Until now, climate modellers have assumed cannot surpass 30°C. The findings may help us understand future patterns.

The dead zone would have been a strange world – very wet in the tropics but with almost nothing growing. No forests grew, only shrubs and ferns. No fish or were to be found in the tropics, only shellfish, and virtually no existed because their high metabolic rate made it impossible to deal with the extreme temperatures. Only the polar regions provided a refuge from the baking heat.

Before the end-Permian the Earth had teemed with plants and animals including primitive reptiles and amphibians, and a wide variety of sea creatures including coral and sea lillies.

This broken world scenario was caused by a breakdown in global carbon cycling. In normal circumstances, plants help regulate temperature by absorbing Co2 and burying it as dead plant matter. Without plants, levels of Co2 can rise unchecked, which causes temperatures to increase.

The study, published today in the journal Science, is the most detailed temperature record of this study period (252-247 million years ago) to date.

Sun and his colleagues collected data from 15,000 ancient conodonts (tiny teeth of extinct eel-like fishes) extracted from two tonnes of rocks from South China. Conodonts form a skeleton using oxygen. The isotopes of oxygen in skeletons are temperature controlled, so by studying the ratio of oxygen isotopes in the conodonts he was able to detect temperature levels hundreds of millions of years ago.

Professor Paul Wignall from the School of Earth and Environment at the University of Leeds, one of the study's co-authors, said: "Nobody has ever dared say that past climates attained these levels of heat. Hopefully future global warming won't get anywhere near temperatures of 250 million years ago, but if it does we have shown that it may take millions of years to recover."

The study is the latest collaboration in a 20-year research partnership between the University of Leeds and China University of Geosciences in Wuhan. It was funded by the Chinese Science Foundation.

Explore further: NASA radar system surveys Napa Valley quake area

More information: 'Lethally hot temperatures during the early Triassic greenhouse' by Yadong Sun et al. is published in Science on 19 October 2012.

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gmurphy
5 / 5 (11) Oct 18, 2012
Kudos to these researchers for shedding insight on the climate so long ago. It's truly incredible how much we can deduce from fossilised remains
hemitite
4.2 / 5 (5) Oct 18, 2012
The 40°C may be an average; if the sea temp got up to 47°C in some areas then there may have been hypercanes:

http://en.wikiped...ypercane
Oysteroid
1.7 / 5 (18) Oct 18, 2012
Wonder who those eel-like creature blamed for the Global Warming?
PinkElephant
3.4 / 5 (10) Oct 18, 2012
@Oysteroid,

Please go to http://www.skepti...dnum.php
and once there, check out the details on the following items:

#2
#45

You might want to take a look at the others, also -- prophylactically speaking.

Happy de-programming...
mountain_team_guy
1.7 / 5 (17) Oct 18, 2012
OK. I get it. AGW is nothing less than an inevitable and impending death of all humanity, oh and also there is no God or heaven. I guess the only thing to do is.... carry on as always.
NotParker
1.8 / 5 (24) Oct 18, 2012
More likely the dead zone was caused by the fact all the continents were in one big mass and oceans did not properly circulate.

I'm sure when all the continents collide again similar things will happen.

It had nothing to do with Co2.
Allex
4.3 / 5 (11) Oct 18, 2012
there is no God or heaven

Why would you care about the Earth if the good heavenly father has prepared something much more pleasant in afterlife for his devoted worshippers? Why would you care about this life, the planet or anything at all? You just wait for the paradise to come. Do us all a favour and go there as fast as you can. Leave this ungodly place to us sinners.
VendicarD
2.8 / 5 (13) Oct 18, 2012
More likely the dead zone was caused by the fact all the continents were in one big mass and oceans did not properly circulate.

Poor ParkerTard. That continent existed for tens of millions of years, and yet he supposes that only during that key heating event did the ocean "not circulate properly".

It's like Magic to him. Much like his claim that wind caused the Arctic ice to melt, or that a non-existant change in "sunshine hours" causes the earth to warm.

He is of course, mentally diseased.
PinkElephant
3.7 / 5 (9) Oct 19, 2012
That continent existed for tens of millions of years, and yet he supposes that only during that key heating event did the ocean "not circulate properly".
Excellent point. To put specific numbers on it:

http://www.britan...1/Pangea

Pangea was fully assembled by the Early Permian Period, some 270 million years ago. It began to break apart about 200 million years ago, during the Early Jurassic Period


So, not only was Pangea fully formed at least 20 million years prior to the end-Permian extinction, it also lasted for at least another 40 million years after the "dead zone" had passed.
Oysteroid
1.6 / 5 (14) Oct 19, 2012
PinkElephant:

Please go to http://www.skepti...dnum.php
and once there, check out the details on the following items:

#2
#45


You know Pinkie, your reply reminds me of Mao and his little red book of quotes. Supposedly, they contained the wisdom sufficient for everything. All you ever needed to do was to quote a quote and bingo - you are automatically right!

Guesd what, it's just not so. Where is that book now? Same place yours is heading. Same place those ancient creatures went. But the Earth's still here and is still warming and cooling and will still be doing that after we are fossils too.

De-program yourself, flush that ROM you use for brain.
Oysteroid
1.9 / 5 (14) Oct 19, 2012
Interestingly, my original comment was more or less tongue in cheek, not intended to be taken too seriously (that's why it was so short). Yet, the religious AGW zealots as represented by the Pinkie just had to briddle at the mere hint of someone making fun of their cherished beliefs. Oh well, fanatics are like that.
PinkElephant
3.4 / 5 (10) Oct 19, 2012
Well it's that, or you're merely regurgitating the same tired and debunked talking points that all the so-called "skeptics" keep on echoing off each other in one grand industry-sponsored circle-jerk. The reason that site (I linked to) even exists, is because you robots are so well-programmed and so predictable. Rather than expend energy repeatedly answering and debunking the same points over and over, why not just write the response down once and point to it each time the same old lies and misconceptions pop up. I call it efficiency.
NotParker
1.8 / 5 (10) Oct 19, 2012

So, not only was Pangea fully formed at least 20 million years prior to the end-Permian extinction, it also lasted for at least another 40 million years after the "dead zone" had passed.


Sure. But this reconsturction was for a sepcific period:

"A paleogeographic reconstruction of the Early Triassic world (Smithian substage) around 252-247 million years ago"

" The formation of Pangea itself choked off cool oceans that had formerly surrounded smaller continents that now lay with much of their land mass lodged in the hot, dry interiors."

http://www.wisege...ying.htm

And don't forget the biggest volcanic eruption of all time "about 251 to 250 million years ago."

http://en.wikiped...an_Traps
PinkElephant
5 / 5 (7) Oct 19, 2012
And don't forget the biggest volcanic eruption of all time "about 251 to 250 million years ago
Exactly. Current thinking goes that this volcanic eruption (i.e. the Siberian Traps, which spewed lava over a huge area of land pretty much continuously for about a million years), wound up belching so much CO2 into the atmosphere that the climate overheated. It's what pushed Pangea over the edge from mostly tolerable to mostly uninhabitable. At the same time, warm oceans became anoxic (and because they were so warm, couldn't scrub all that extra CO2 out of the atmosphere quickly enough), causing blooms of SO2-producing bacteria, which both poisoned the oceans and emitted enough SO2 to poison the air over much of the nearby land as well.

Anyway, it was the volcanoes that made the difference, explaining the timing of the extinction event (whereas the continent-ocean configuration was present both long before and long after the extinction event.)
Osiris1
2.7 / 5 (6) Oct 19, 2012
There is a Dr Michael Ramfino from City University of NYC with a theory of another event that may be applicable here. In this other event, the Chixculob Crater off yucatan, about 130Km diam., was caused by a meteor strike. Dr Ramfino postulates that this strike rang the earth like a bell, with the shock waves through and around the earth meeting at the other side of the world and rupturing the crust there as well..and more. At the time of Chixculob, this point was in the the continent of India which was on its way to its meeting with Asia. Due to this, the Deccan Traps, a lava pile up to 8000 ft deep was erupted by open crack or slit volcanism. The Siberian traps may have similar origin. Need to find where the other side of the world was when THAT meteor hit. The drawing above says it would appear to be off of Antarctica. Look for a huge crater there...maybe over 200km wide and 230MY old! Possibly under Ross Ice shelf.that is circular!
PinkElephant
5 / 5 (5) Oct 19, 2012
@Osiris1,

The major difficulty with a Permian impact hypothesis (even as a mere trigger for the Siberian Traps) is not absence of a known crater, but absence of all the other typical impact correlates in the applicable rock strata. That is, one would expect elevated levels of rare earth metals, breccia, glass beads or nanodiamonds, maybe a layer of carbon ash from world-wide fires, etc. -- NONE of which are observed.
chromosome2
2.3 / 5 (6) Oct 19, 2012
Global warming deniers in politics make me feel like I'm strapped to a seat in a bus being driven through the mountains by a paranoid schizophrenic who thinks satan is chasing him.
JoeBlue
1 / 5 (11) Oct 19, 2012
Of course there is no real way to prove any of this.
Torbjorn_Larsson_OM
4.4 / 5 (7) Oct 19, 2012
There is, IIRC, other work that puts the prolonged doldrum down to repeated new environmental changes. But the temperature record is certainly convincing.

@ Osteroyid: No one "blames" climate on the process or its forcing factors. CO2 can be a dominant driver, as seen then and as seen today.

@ mtg: These results point to a risk, greater than earlier predicted, if CO2 rises. No more, no less.

@ NotParker: Not enough driving force, I take it. (Haven't checked the paper yet.) Only the GW as such, and especially a GW gas increased forcing, or they wouldn't propose it. It is peer reviewed you know.

@ Osiris1: No one else believes in such a cockamamie theory though. It was believed to have happened on Mars, the Tharsis bulge, but regular hot spots is enough for the prediction.

@ JoeBlue: Except that the paper just did, predicted and tested. Your alternative, no theory at all, does nothing of that and is a generic non-starter in science. You may want to read up on how science is done.
Osiris1
1 / 5 (1) Oct 19, 2012
Good point Pink Elephant, no one has found a world-wide tell-tale layer of rare earths such as the iridium rich layer from Chixcolub, nor has the smoking gun of a large crater been either found. It would not hurt to take a look at this area around Antarctica with remote sensing, satellites, etc.; this as long as the graphic showing Pangea at the conjectured time of this tragedy was in its actual place.

There is however the P-T boundary...just no rare-earth layer. Could it be we got slammed by a different kind of asteroid, or some other external event, the conjecture of which maybe someone else here can shed maybe his own real light on...constructive and not negative if you please. Ramfino's idea seems to have an eerie ring of truth and if it happened once, why now twice. Question, like our own resident pachyderm said, why no layer? Chixcolub did not affect the drift of ancient India into EurAsia; neither this event affect global continental drift either...impacts too small?
PhotonX
5 / 5 (1) Oct 19, 2012
Osiris:
Dr Ramfino postulates that this strike rang the earth like a bell, with the shock waves through and around the earth meeting at the other side of the world and rupturing the crust there as well...


Torbjorn:

@ Osiris1: No one else believes in such a cockamamie theory though. It was believed to have happened on Mars, the Tharsis bulge, but regular hot spots is enough for the prediction.


Maybe this isn't what you meant, but human anatomy allows for contracoup fractures that occur on the side of the cranium oppisite the impact. I.E. A right(or left)-sided blunt force trauma travels in shock waves around the skull until they meet on the other side and cause a fracture there. I don't have any trouble visualizing a similar process on a planet.
Osiris1
1 / 5 (2) Oct 20, 2012
Correction, look for a crater in New South Wales, Australia along the Great Dividing range, or hidden under it. May be in rock strata 250MYA if exposed. This is very generally approximate and IS a guess from the projection of the map.
mountain_team_guy
1 / 5 (9) Oct 22, 2012
there is no God or heaven

Why would you care about the Earth if the good heavenly father has prepared something much more pleasant in afterlife for his devoted worshippers? Why would you care about this life, the planet or anything at all? You just wait for the paradise to come. Do us all a favour and go there as fast as you can. Leave this ungodly place to us sinners.


You got it backwards, just as I expected. I'm the sinner and I would be damn suprised if you thought you fell into that category. BTW, if you really want to save the Earth from the threat of AGW, don't YOU think the only really significant and lasting contribution YOU can make is to trim your family tree? Unless of course you have a plan to eliminate your personal emissions of greenhouse gases, you seem to be all talk.
Allex
1 / 5 (2) Oct 22, 2012
Unless of course you have a plan to eliminate your personal emissions of greenhouse gases

Don't bother your sweet spiritual head with my plans. Come up with some of your own. Or would you rather wait for a divine revelation? Well, that seems like the proper way to act - wait until you get a sign from THE BOSS. Until then, everything is O.K.
you seem to be all talk

Go pray. That is, and always has been, the easiest solution and it seems you are projecting it onto others. And while you at it, sacrifice a goat.