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
Policy based science?
Social Geoscience?
tty
October 20, 2012 at 12:42 am
It is largely meaningless to try to comment on this junk press release. To take just one sentence from it:
“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.”
1. Conodonts aren’t fish, they aren’t even vertebrates.
2. Conodonts don’t have skeletons
3. Conodonts don’t have teeth.
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While I agree with the thrust of your comment, I would like to point out that condonta is generally place within vertebrata today, re: Janvier, P (1995) Conodonts Join the Club. Nature. Whether one calls them a fish is a matter of definition. Are hagfish fish? How about cephelachordata?
Popular literature calling conodont oral elements “teeth” doesn’t bother me too much as its common enough, but it does indicate that the authors are ignorant or consider their audience to stupid to handle the distinction.
I did find that line about skeletons using oxygen completely bizarre.
D. Patterson says:
October 20, 2012 at 6:15 am
Sorry I did mean the entire period from the Permian right up to the Cretaceous. With regards to long periods of ice this represents durations more than 10 million years with likely not a single thaw at any time. (I should had stated this) Antarctica only skirted the South pole during this period with around 270 degrees away from the pole still ocean. Therefore in this situation it was still prone to thaws at times. Unlike today when a large land mass is centered over the pole like Antarctica and in this position I don’t ever see a thaw until the land mass moves away. Greenland today not far from the North pole is cut off from warm ocean currents, unlike large land masses most of the time during the Permian up to Cretaceous period. Therefore this was not referring to no ice caps and no cold temperatures for shorter durations.
Conodonts are very important because they are one of very few creatures that were seemingly oblivious to the extinction devastating everything else. It has been suggested that their resilience resulted from their lack of calcerous parts. They survived the extreme seesaw of 13C excursions (which likely are far more diagnostic of the lack of recovery than temperature) in the early Triassic as well, but died out mysteriously (and unfortunately) during relatively tame times in the Late Triassic.
Imagine the polar amplification.
John Silver says:
October 19, 2012 at 6:03 am
There are places in the Atacama desert today that doesn’t even have bacteria.
How does this zone differs from the desert zone of today, Sahara, Arabian Desert and so on?
I seem to recall that the Atacam desert is very, very dry. I suggest that it is the lack of moisture rather than the heat which results in extremely low levels of biodiversity in the Atacama desert. If it is dryness, then the Atacama would be a poor anology to the situation being described in the paper.
There are many useful posts in this string that raise thoughtful issues about the paper.
My preliminary view is that the authors are addressing an important issue but that they may well have over-generalised from a very limited sample and that further work needs to be done.
None of the posters appear to have actually read the paper, which means that there is necessarily a bit of guesswork involved. Nevertheless, the guesswork is often well-informed.
OTOH, analysis demonstrates that the following posts do not add lustre to the string:
omnologos says: October 19, 2012 at 4:12 am
‘Does anybody remember when Asteroids where the culprits du-jour and the Permian extinction plus lack of new species blamed on them?’
Comment: The issues raised in the paper are not a memory test. But try looking downstring: asteroids are alive and kicking as explanations.
jgmccabe says: October 19, 2012 at 4:16 am
‘Seems like a rather bizarre claim! Do they have proof, or is this just wishful thinking?’
Comment: ‘Seems like…’has no definitive scientific meaning. There is no evidence for the charge of ‘wishful thinking’, whatever that means, scientifically.
Scuzza Man (@ScuzzaMan) says:
October 19, 2012 at 4:17 am
This is ridiculous. That 50 to 60 degrees might be uninhabitable for most mamals, doesn’t mean we should be afraid of the sunrise…
Comment: ‘Ridiculous’ has no scientific meaning. It does have emotional content but this is a scientific blog. Being, ‘afraid of the sunrise…’ has no scientific meaning. OTOH, Freudians could probably make a meal out of it.
Brian H says:
October 19, 2012 at 4:31 am
Nothing but ferns and shrubs on land? How did they survive? And why didn’t they proliferate and “take over”? I suspect logic leaps and lapses.
Comment: ‘Suspicion’ is used in the context of paranoia. Perhaps you mean ‘sceptical’?
R Taylor says: October 19, 2012 at 4:45 am
“levels of Co2 can rise unchecked, which causes temperatures to increase”
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And pain causes tumors, so we can treat cancer with aspirin. We can only pray that the curative magic of aspirin has no plateau at a relatively low level.
Comment: Analogy is a weak form of logic, particularly in scientific discussion. A false analogy, such as this, merely misleads.
TimTheToolMan says: October 19, 2012 at 4:53 am
I’d love to see the paper. My first instinct is to think…
Comment: Suggest you check the scientific definition of instinctive behaviour. You probably mean my first learned behaviour is to think…
Paul Coppin says: October 19, 2012 at 4:56 am
New science PhD degrees have apparently joined their colleagues over in Sociology as being nothing more than a bad joke at public expense. Redefining “dumb” (PhDs from the 80s through 2000s) and “dumber” (graduate students of those foementioned PhDs). A complete collapse of western rational education.
Comments: You have not read the PhD dissertations. On the basis of this comprehensive ignorance you call the degrees a ‘bad joke’ and declare that there is, ‘A complete collapse in western rational education.’ Your post does go some way to demonstrating that western rational education is imerfect.
higley7 says: October 19, 2012 at 5:26 am
“Please, sir, can we have more funding?”
Comment: This is not a scientific comment. It is personal attack.
Pamela Gray says: October 19, 2012 at 5:57 am
It concerns me that Ph.D.’s were awarded.
Comment: Absence of information is not a sound basis for concern about specific issues. It is a basis for concern about the absence of information.
Just an engineer says: October 19, 2012 at 5:33 am
Hate to have to point out the bleeding obvious, but there aren’t a lot of species living in Death Valley either!
Comments: What has ‘hate’ got to do scientific comment? What does ‘bleedin’ mean in scientific terms? Putting aside the unscientific language, the claim is incorrect.
Tom Murphy says: October 19, 2012 at 6:08 am
Anyone who is in the know on this issue accepts that it was aliens …sarc
Comment: Sarcasm may be drama but it is not science.
cui bono says: October 19, 2012 at 6:45 am
Well done Anthony. The script for Al Gore’s next science fiction movie is already written.
Comment: Sarcasm may be drama but it is not scientific.
D. Patterson says: October 19, 2012 at 6:51 am
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?
Comments: Suggest you discuss the asteroids theory with the person who raised it, upstring. ‘…smell half baked’ is not a scientific term.
Jim Clarke says: October 19, 2012 at 7:26 am
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/
Comment: Sarcasm and an ad hominem attack are not scientific.
Tim Walker says: October 19, 2012 at 7:28 am
Good job gentlemen and how many million do you say you need for a follow up study?
Comment: Sarcasm and an ad hominem attack are not scientific.
Henry Clark says: October 19, 2012 at 7:40 am
…“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….
Comment: Ad hominem attacks abound here – unscientific.
Jim Clarke says: October 19, 2012 at 8:50 am
It appears that climate science is now completely run by the Joseph Goebbels Foundation.
Comments: Reductio ad Goebbels is not scientific. It is a vicious ad hominem attack of the worst sort. It defiles the memory of the Holocaust.
Conodonts are very important because they are one of very few creatures that were seemingly oblivious to the extinction that devastated everything else. It has been suggested that their resilience resulted from their lack of calcerous parts. They survived the extreme seesaw of 13C excursions in the early Triassic which likely are far more diagnostic of the lack of recovery than temperature. I believe these swings represent biological demand for 12C which underwent a crecendo of fluctuations indicating recovery and subsequent extinction in the early Triassic before settling down. Conodonts died out mysteriously (and unfortunately) during relatively tame times in the Late Triassic.
http://wp.me/p1uHC3-5c
18O incorporation is indeed temperature dependent and is the best proxy for temperature we have. However, it is also selected against in biological processes for the same reason that the heavy isotope 13C is. During extreme extinction events it is likely that the lighter isotopes were far more abundant and that biological selection would weigh against the temperature signal.
I should have said weigh ON the temperature signal. High temperatures=low 18O incorporation. Abundant 16O preferentially incorporated would skew the temperature signal to appear hotter than it really was.
An interesting piece of experimental research, with useful new proxy data from fish teeth. However it has been shamelessly hi-jacked for AGW alarmism.
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.
No. Plants help regulate temperature by sustaining the hydrological cycle over land and thus maintaining water vapour and clouds over land. This is the way that tree evolution during the Silurian and Carboniferous brought down global temperatures ( Beerling and Berner 2005 ). The evolution and growth in size of trees, increased plant biomass and the transpiration stream, causing wetter and cooler weather over land. CO2, as always, is a responsive and following indicator, not a driver.
At the start the Earth was a paradise then the co2 levels rose and it all went wrong because of this which is typical thinking from British geologists who make no secret of their politics on the present AGW scare even in this paper.We don’t see the large temperature sensitivity to co2 , they use to generate huge temperature rises in past extinctions, in Earths climate today.I don’t think anyone knows what caused the permian mass extinction apart from todays co2/climate change advocates , they just know that co2 causes a large rise in global temperature without proof, and this enables these people to say that the global temperature today could never fall but only rise because of increases in co2.How long would world temperatures have to not follow the catastrophic rises they predict before they admit that they are wrong.