From the University of Leeds , 250 million year old certainty where there was none before, now megasized.
Tropical collapse caused by lethal heat
Extreme temperatures blamed for ‘Dead Zone’
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-Permian mass extinction, 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 Triassic period 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 extreme temperatures kept life from re-starting in Equatorial latitudes for millions of years.”
It is also the first study to show water temperatures 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 sea-surface temperatures cannot surpass 30°C. The findings may help us understand future climate change 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 marine reptiles were to be found in the tropics, only shellfish, and virtually no land animals 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 mass extinction 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 [19 October 2012] 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.
For more information:
‘Lethally hot temperatures during the early Triassic greenhouse’ by Yadong Sun (University of Leeds and China University of Geosciences), Michael Joachimski (University Erlangen-Nurnberg, Germany), Paul B. Wignall (University of Leeds), Chunbo Yan (China University of Geosciences), Yanlong Chen (University of Graz, Austria), Haishui Jiang (China University of Geosciences, Lina Wang (China University of Geosciences) and Xulong Lai (China University of Geosciences) is published in Science on 19 October 2012. For a copy please view the web page http://www.eurekalert.org/jrnls/sci/ or contact the Science press team, phone +1 202-326-6440 or email scipak@aaas.org
For interviews please contact Esther Harward, University of Leeds press office, phone +44 113 343 4196 or email e.harward@leeds.ac.uk
If great parts of Pangaea were without major vegetation after the preceding catastrophic events the heat over the continent could have risen substantially. It could also have led to diminshed cloud formation and conseqently to increased short-wave sun-radiation warming the oceans. CO2 causes infrared radiation, which can penetrate the ocean-surfaces only a few millimeters. It may have been hot at those times, but it ist not explained why CO2 should be the major culprit.
Anthony,
Is the following attribution actually stated in the paper?
“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.”
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.”
————————————————————————————————————————-
What an odd thing to say.
Well done Anthony. The script for Al Gore’s next science fiction movie is already written.
What was the temperature on the second Monday of Permian October 248M? If they cannot compute that then it is finally clear to me why they cannot get the forecast right for next Monday.
It is interesting to see how they blame the extinction on “Global Warming” and not on one or more major impactors such as the 10 kilometer diameter asteroid that created the 125 mile wide Bedout Crater off the coast of Australia. Does anything smell half baked in this paper?
The reason why modelers assume an upper limit of 30-32 degree C is evaporation, which increases almost exponentially with temperature and carries away the heat thus cooling the water. The assumption is that the incoming heat cannot keep up with the evaporation. There is only one condition in which this mechanism does not work: when the whole planet is blocked off by clouds which trap the heat and thus do raise the temperature of both atmosphere and the oceans. A cloud cover that thick would cause the surface to be seriously dark at sealevel, possibly making photosynthesis impossible.
The map seems to contradict what we currently understand about northern hemisphere heating. Ie The dead zone narrows over land when we expect it to widen. WUWT?
Pedants corner: that would be the Univ. of Erlangen-Nürnberg (or -Nuremberg in the anglicised version), not Nurnburg,
There’s no doubt that there was a mass extinction around the end of the Permian. The Paleozoic coral groups died out, their niche later being later filled by other coral groups, only distantly related. However many groups survived, such as tree ferns, and ‘sea lilies’ (sedentary marine animals, also known as crinoids). Both groups still ‘teem’ today, in suitable environments. The conodont animals (which I gather were something like modern lampreys) seem to have survived the late-Permian extinction, but later succumbed as they are no longer around today.
It looks like an interesting study, but I’d be cautious about drawing bold conclusions regarding global climate from a study of a single group of localities. As conodonts have no close modern relatives, and it seems we don’t know much about their mode of life, I’d also like to see some O2 isotope values from other co-existing organisms at the Chinese sites. However I’m not a fossil expert and I’m sure others can throw more light on this. Willis E may have something to say about prolonged ocean surface T approaching 40C.
Al right, I’ll bite. How much CO2 was there at this point in pre-history that they say coused this “super greenhouse”?
But the land and sea were differently configured back then. With water surrounding our current separated land masses the likelihood of anything similar happening for more millions of years are small. Sorry, Dr. Hansen, this would have been a godsend for you!
Anthea
40 C is 104 F. Seawater boils at a higher temperature than pure water, but this says the oceans surface was literally “boiling hot” Interesting paper. I’ll wait for another 3 or 4 that confirm it before I believe it. (Without any papers that directly contradict it).
So what killed the plants that caused the CO2, if CO2 was the culprit and how did they determine that CO2 was the culprit? And why did the tropics warm and the poles maintain more stability while present day warming is supposed to be the other way? Is it all about ocean currents?
Assuming the uncontested validity of temperature from eel’s teeth assumptions over other proxies that did not hint of this, of course. Sounds like jumping from an isoated observation into a pre-determined conclusion to me.
What seems to be missing is a description of the physics involved. How any concentration of CO2 can push temperatures that high, and why there was enough O2 available for these creatures to grow/survive. After all, you need to suck O2 out of the atmosphere to combine with the C to form CO2. Then there is the question of where the large concentrations of carbonates are which is the only reasonable explanation of how the CO2 was removed.
Isn’t it sad that these people have been taken in by the CO2-GW scam when from three directions you can prove it cannot occur.
Assuming the high temperatures were correct, the most likely explanation is that at that time, the atmosphere was much thicker and the extra tropical heating was from increased lapse rate warming, currently ~24 k on average.
This whole thing just gets weirder and weirder.
Once scientists would put things forward as ideas.
Now it seems to be all settled facts…….
….I guess they must be getting smarter.
One slight problem with their hypothesis: The Early Triassic rise in atmospheric CO2 followed behind the rise in temperature: Phanerozoic Temperature and CO2 (modified after Berner, Royer & Veizer)
The only way their findings will ever “help us understand future climate change patterns,” will be if they finally accept the fact that the carbon cycle is driven by the climate cycle.
Okay…let’s assume for the sake of argument that measurement of one proxy in the South China Sea is sufficient to conclude that the entire tropical earth was baking at 40-50 C, a quarter of a billion years ago. Can atmospheric CO2 really be the cause of that heat?
According to the image linked below (and other CO2 histories) the concentration of CO2 in the atmosphere did increase to around 2000 ppm from 270 to 250 million years ago. This increase was a return to about half the concentration of CO2 that was present when life on Earth really started to blossom. This begs the question…if 2000 ppm creates heat so intense that most life can’t survive, how did 4000 ppm create environment so nice that life began to flourish?
http://www.geocraft.com/WVFossils/PageMill_Images/image277.gif
Maybe we are just to ignorant about stuff more than 250 million years ago, so lets throw that out.
What happened after 250 million years ago? We had the ‘life explosion’ known at the Jurrasic Period. The planet was teeming with life! Oh, and look, CO2 concentrations for much of the Jurrasic were between 2200 to 2500 ppm! Again, we find a higher concentration of C02 than 250 million years ago, yet a very life-friendly Earth.
Assuming that the alleged heat of 250 million years ago was caused by increasing atmospheric CO2 doesn’t seem to make any sense at all! What could have possibly led them to that conclusion against all the available evidence?
Could it be…FUNDING?
/sarc off/
Good job gentlemen and how many million do you say you need for a follow up study?
So, without qualifying my credentials, as I understand it, there should be no Fossil or related record in the South America zone, in the upper two thirds of that zone, for that period.
As I also understand it, the fossil record for most of North America, in the same zone, for the same period should be entirely absent.
Even given the bias for reporting against the actual presence of ancient fossil, as well the well known and obvious contradictions in the geophysical, paleontological and of course the much disputed cryptozoological discrepancies, why is there well documented records that predates, post-dates and extends well-into and through this period?
One could postulate, that given the obvious evidence, that theories to the contrary, as noted above, could well be factually incorrect.
That is, providing, they are based on well researched fact. Of course, should this not be the case, then obviously any nonsense will do?
“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.”
This is merely the authors hypothesis, stated as fact. Very misleading.
The Abstract Reads: “Global warming is widely regarded to have played a contributing role in numerous past biotic crises. Here, we show that the end-Permian mass extinction coincided with a rapid temperature rise to exceptionally high values in the Early Triassic that were inimical to life in equatorial latitudes and suppressed ecosystem recovery. This was manifested in the loss of calcareous algae, the near-absence of fish in equatorial Tethys, and the dominance of small taxa of invertebrates during the thermal maxima. High temperatures drove most Early Triassic plants and animals out of equatorial terrestrial ecosystems and probably were a major cause of the end-Smithian crisis.”
Some data lots of assumptions and way to many gross generalizations to be call science. Could we call it scientific speculation? I am sure it is an interesting paper but probably not worth the cost of the pay wall.
I posted this idea some time ago but it hasn’t appeared.
It’s easy to prove from three directions that there can’t be any CO2-GW above ~200 ppmV concentration. So, the on;y logical explanation of the high temperatures was that the atmosphere was much denser than now so lapse rate heating, presently ~24 K, was much greater.
No effect of CO2 change is possible other tna this.
I’m curious as to how this paper is organized. Is the above explanation an assertion made within the paper, or is it a conclusion which is directly supported by an analysis of the evidence which examines in detail the processes by which CO2 concentrations rose “unchecked”, and the processes by which those rising CO2 concentrations might have resulted in atmospheric and ocean warming?
“It is also the first study to show water temperatures 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 sea-surface temperatures cannot surpass 30°C.”
“First study” = contradictory to every other study, to every study made before the era of politicized “science”? The author quoted at the end does a poor job of even pretending to be unbiased, giving no reason to assume honesty is more likely than dishonesty.
I’d have to look up the details, but I believe Dr. Lindzen once mentioned how there is evidence that equatorial ocean temperatures have never been more than a rather limited amount (like a degree or two, IIRC, although with much more temperature variation nearer the poles) higher than they are now.
While it would be hard to place an exact limit on the temporary temperature rise which could occur from other sources which have been considered as potential causes of the end-Permian extinction like an enormous asteroid impact and/or massive volcanic eruptions, radiation emission scales up with the fourth power of temperature (in Kelvin), making it very hard to increase temperature much further in the tropics for long. CO2 with its diminishing returns is definitely not going to do it with plausible values.*
* The atmosphere of Venus, with hundreds of thousands of times as much mass of CO2 as Earth’s atmosphere, is not an exception but rather an illustration of the limited effect of even going from 0.04% to near-100% CO2: At 1 atm, Venus temperatures are only moderately above earthlike, not much for a planet closer to the sun under double the solar irradiance, and it is only after the effect of the lapse rate going down through an ocean of atmosphere to the surface under 90 atm that far higher temperatures are reached. As http://wattsupwiththat.com/2010/05/08/venus-envy/ notes:
The amount of warming (or cooling) per unit distance is described as the “lapse rate.” On Earth the dry lapse rate is 9.760 K/km. On Venus, the dry lapse rate is similar at 10.468 K/km. This means that with each km of elevation you gain on either Earth or Venus, the temperature drops by about 10C.
It is very important to note that despite radically different compositions, both atmospheres have approximately the same dry lapse rate. This tells us that the primary factor affecting the temperature is the thickness of the atmosphere, not the composition”
“It isn’t the large amount of CO2 which makes Venus hot, rather it is the thick atmosphere being continuously heated by external sources. It isn’t the lack of CO2 on Earth which keeps Earth relatively cool, rather it is the thin atmosphere. Mars is even colder than earth despite having a 95% CO2 atmosphere, because it’s atmosphere is very thin. If greenhouse gases were responsible for the high temperatures on Venus (rather than atmospheric thickness) we would mathematically have to see a much higher lapse rate than on Earth – but we don’t.”