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
BTW, for those who are not up on there paleogeography, during the end permian, south china was over a quarter of the way around the world, at the opposite side of the tethys, from pangea. Also most of the earths land mass was in the two belts that are always mostly desert. One probable explanation for the expansion of these deserts was global cooling.
The evidence seems to indicate the forests of Australia were devastated in an instant by the impact of at least one asteroid about 10 kilometers in size. Scientists examining oil exploration drilling cores from years earlier discovered evidence of the breccia, shocked quartz, and other indicators associated with asteroid impacts. A 125 mile wide crater was identified at the submarine drilling site. Other investigators also identified another impact site in Australia where an asteroid estimated to have been 5 kilometers in size made its impact. Other investigators identified Buckyballs and other markers in the Permian-Triassic extinction layers. These and other papers narrowed the time of the impact/s or extinction to about a 100,000 year time period. The gap in the coal bed in Australia is likely attributable to these major asteroid impact events.
The totality of the permian-Triassic extinction event is likely to have been a combination of effects including, major asteroid impact events, orbital mechanics, formation of the supercontinent, the late Carboniferous ice age and glaciations, low sea level stands due to glaciations, the Siberian Traps vulcanism, acid rain and snow, hydrogen suphides, anoxic seawaters, and more. The siberian Traps vulcanism amy be linked to the asteroid impact/s and their effects upon the Earth’s mantle.
As a geologist, I would say that this study – indeed the Permian extinction and the lead up and post-event play out – should be fertile ground for dozens or hundreds of Masters and Ph.D theses. Go for it, kiddies!
DesertYote says:
October 19, 2012 at 4:40 pm
BTW, for those who are not up on there paleogeography, during the end permian, south china was over a quarter of the way around the world, at the opposite side of the tethys, from pangea. Also most of the earths land mass was in the two belts that are always mostly desert. One probable explanation for the expansion of these deserts was global cooling.
During the Carboniferous the CO2 levels plummeted from thousands of ppm to the few hundred ppm seen during the present ice ag in which we live today. The continents were in the process of forming a new supercontinent of Pangea. Gondwana had moved astride the Antarctic circle and formed a gigantic ice cap much larger than we see today. This ammmmoth ice cap lowered the worlds sea levels, The lowered sea levels exposed vast extents of the continental shelves formerly harboring rich marine life communities in shallow waters. Their loss of habitat severely reduced their populations and biodiversity.
Off the western shores of Laurentia there was an archipelago of mountainous islands which intercepted the moisture in the winds. The dried out air masses which proceeded eastward into laurentia promoted the development of vast deserts which waxed and waned in size through the permian and into the Triassic. These vast stretches of continental deserts contrasted with the lush coal-forming vegetation on the eastern shores of Laurentia aand the Paleo-Tethys Sea.
It was during this Late Carboniferous, Permian, Triassic period that the low sea levels and formation of the Pangea supercontinent created the rare instance of the terrestrial land area approaching the same area of the Earth’s surface as the oceans. It also marked the time when the Pangea supercontinent extended all the way from the antarctic Circle to the Arctic Circle, restricting the circulation of oceanic currents.
21st Century Grimms Fairy Tales.
Yeah, right! I have Views on oxygen isotopes in fossil material as old as this.
Any such work must first demonstrate that ALL the sampled beasties have remained closed systems every since they died.
A New Zealand researcher made a simialr study made of Cretaceous belemnites a few moons back. Their tests had long recrystallised. What the researcher was seeing – but never realized at the time – was not the temperature of the original living environments but a mixed signature obtained from the rocks the fossils had been contained in throughout geologic time.
There is a famous sequence of Permian evaporates in Germany that have a simailr issue: The Zechstein formation. Their present salt assemblages can only be produced from very high water temperatures. But what we are seeing are not the original precipitation assemblages but those of a post-deposition reconstitution at elevated temps.
D. Patterson
October 19, 2012 at 5:18 pm
Off the western shores of Laurentia there was an archipelago of mountainous islands which intercepted the moisture in the winds. The dried out air masses which proceeded eastward into laurentia promoted the development of vast deserts which waxed and waned in size through the permian and into the Triassic. These vast stretches of continental deserts contrasted with the lush coal-forming vegetation on the eastern shores of Laurentia aand the Paleo-Tethys Sea.
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Thanks for this information. I am familiar with the western Laurentian archipelago (I live in the western us) but had not thought to much on its affect on rain, nor have I read any papers talking about this (though its been about 15 years since I last did a serious review). It should have been obvious to me. The last theorizing I had read talked about the deserts expansion do to cooling cause by the Siberian Traps volcanism in addition to the unique geography of the permian.
I found it interesting that the press release talked about the equatorial zone being hot and wet but too hot for life.
I just noticed something, the dipnoid order Lepidosireniformes seems to have survived the extinction event living precisely in the region the graphic calls the “Dead Zone”.
All that this proves to me is that science is as trendy as Hollywood.
Here is a Zoom-in of the highest resolution Temperature and CO2 estimates covering the Permian Extinction event (for those interested in the actual data).
What is not recognized is that the proxy evidence for Temperatures is that they fell considerably right at the event (251.4 Mya). It was hot before and after the Permian Extinction but not right at the event timeline. What is, however, right at the event, is the Siberian Traps basaltic flood event volcanoes (the largest volcanoes known about – large enough to cover the entire US in 1 km of magma).
http://s17.postimage.org/5zpwzyvcv/Permian_Extinction.png
Looks like a ‘C’ Grade sci fi story to me
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!
There are quite a few higher level animals including a snake- mostly limited by the lack of water. This study says no lack of water so what’s the problem.
I was just thinking about what I said earlier about the survival of Lepidosireniformes. One factor could have been that this order evolved to deal with anoxic conditions.
Dang, I forgot to mention that Lepidosireniformes are an order of lungfish. They originated in the early devonian and are still with us today.
The Siberian Traps vulcanism is suspected to be the consequence of one or more asteroid impacts.It is conjectured that the impact or impacts transmitted their force through the Earth’s interior and the forces were reflected and concentrated at points where the concussive waves crossed. The siberian Traps is suspected of being one of those points where the reflected concussions ruptured the continental plate on the other side of the Earth from where the impact took place.
Like a horse race, there is a keen competition underway to identify the impact or impacts responsible for the ELE (Extinction Level Event/s). There are a number of contenders.
One contender is an impactor that was 4.8 kilometers or 3 miles wide which produced a crater 75 miles or 120.7 kilometers in diameter underneath Australia.
Another contender is the Bedout Crater 150 miles wide produced by a 9-10 kilometer sized asteroid impacting off the coast of Australia. Large enough to fit from the surface of the Earth to well above the Earth’s troposphere, it hadd the force sufficient to destroy most life on the Earth.
Then you have the contender claiming to be the world’s largest asteroid impact. NASA researchers describe this monster as an Earth shattering asteroid 50 kilometers in size impacting Antarctica in the time of the Permian-Triassic extinction. They suggest the impact fractured the continental plates and the MASCON (mass concentration) caused the continent of Antarctica to rift away from Pangea and Gondwana.
As if the Antarctic impactor wasn’t sufficiently large sizeed enough, other researchers identified an impact site stretching from a point off the western coast of Cameroon in West Africa, along a circular arc around North Africa, and down Eastern Africa and through the Rift Valley. They conjecturre this impact was large enough and powerful enough to causee the breakup of Pangea supercontinent. The MASCON (Mass Concentration) is described as causing the continental plates to slide away from the mass of the intruding asteroid in the Earth’s mantle.
Complicating the search for the true culprit of the mass extinction/s is the possibility there were multiple impacts causing multiple subsidiary extinction events. It is not uncommon for asteroids and comeets to produce multiple impactors upon their approach to the Earth’s and Moon’s gravitational fields. Multiple impactors could have struck the Earth on the same day. Multiple impactors traveling along the same Solar orbital path could have struck the Earth at different times ranging from days to centuries apart.
One thing is certain, however. Such impacts result in planetary wide destruction of most species of life on the Earth. The number of such events in the past 550 million years are limited. The geology further limits the dates these impact craters could have been formed. At the rate things are going now, we are beginning to see more impacts and impactors than we have mass extinction events to math up with them. This situation does not even account for the possibility of eveen more impact craters which still remain undiscovered from the Permian-Triassic extinction period.It may not be too early to conjecture whether or not there could have been multiple impacts responsible for the Permian-Triassic mass extinction event.
In the face of so much evidence of impact craters at the time of the mass extinction, why would any credible scientist ignore their certain effects to pursue CO2 and Global Warming without an ELE impact event to explain it?
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.
Conodonts are a completely extinct group of animals, probably chordates, which did indeed superficially look something like eels. They didn’t have teeth, but they had “elements” that look somewhat tooth-like and probably had a similar function. Incidentally these almost certainly aren’t homologous to vertebrate teeth.
And, yes, in principle oxygen isotopes from conodont elements can be used to determine the temperatures of the waters where they lived. But:
– the elements must not have been diagenetically altered
– the salinity of the water must be similar to modern conditions (or separately determined)
– the oxygen isotope composition of the seawater must be similar to modern conditions (or separately determined)
– there are unexplained inter- and intra-species differences in the composition of conodont elements from the same site.
– there are differences within a single conodont element probably due to physiological factors
– laboratory protocol is very important to get consistent results
– since conodonts are extinct there is no way we can directly verify results
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!
“Death Valley’s great range of elevations and habitats support a variety of wildlife species, including 51 species of native mammals, 307 species of birds, 36 species of reptiles, three species of amphibians, and five species and one subspecies of native fishes.”
(http://www.nps.gov/deva/naturescience/animals.htm)
That is a lot more species than in any boreal forest for example. The density of most species is low due to the scarcity of water, but the general rule that hot areas have more species than cold areas holds even in Death Valley.
This paper made me think about what a marvelously ‘buffered state” the world is usually in.
Should it get warmer right now the ‘habitable zone’ move northwards as the frozen ‘dead zones’ towards the poles warm up.
But we are perhaps less buffered in the other direction: With the tropics being entirely habitable right now, any cooling will only reduce our ‘habitable zone’.
D.Paterson,
well whatever caused the conditions, it must have been a nasty place. If there we no plants to form coals, then there were no animals and insects feeding on those plants, and so on.
“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.”
That is an odd claim since the Earth today is proof it wasn’t unchecked. Do they also have a theory for what stopped it? It seems to me that the really problem assuming they’re correct, is deforestation.
Deep ocean hot springs populated by a host of organisms do not exist. During five million years this was not possible
!http://youtu.be/M_26krewDWk
Quite simply if carbon (CO2) was so powerful back then on global temperatures we would have seen it already over recent decades. The position of the continents and very warm circulation of ocean water around them was responsible for the general much higher temperatures back then. There were no land masses around the poles so no accumulation of ice could occur for long periods. Global albedo levels were much lower than today, mainly down to this different positioning of the continents. This type of warming could never happen today until land masses move from the poles. Hence, this would take many millions of years in future just for the continents to become favorable again.
You didn’t state which time period you are commenting about other than to imply the Permian-Triassic extinction. In any event, you are mistaken. There was a mammoth ice cap and cold temperatures during the Late Carboniferous. Gondwana was very much astride the Sotuh Pole and Antarctic Circle, and it was very heavily glaciated.
The Permian saw the The Siberian plate was approaching the North Pole and was entering the Arctic Circle at its northern extent. No Arctic ice cap had yet formed. During the Permian the Siberian continental plate moved closer to the North Pole and was somewhat intruding further into the Arctic Circle. Gondwana was still in the Antarctic Circle and moving northwards. The Antarctic icecap on Gondwana expanded far beyond the Antarctic Circle towards the southern tropics. Much of the Southern hemisphere was heavily glaciated.
By the time of the Late Permian and the Permian-Triassic mass extinction, the Earth had warmed enough to lose the Antarctice ice cap, but Gondwana’s huge continental land mass was still astride the Antarctic Circle and the Sotuh Pole. At the same time the super continent stretched all the way from the South Pole and well into the Northern Hemisphere. The Siberian continental plate reqached further into the Arctic Circle with its northern most tip very close to the North Pole. A small ice cap formed on the northern end of the Siberian continental plate, even though the glaciation and ice cap on Gondwana had disappeared.
The Triassic warming brought warm temperate climates to the Antarctic and Arctic Circles. The ice caps became a distant memory.Gondwana was still astride the Antarctic Circle. The continental landmasses stretched from the South Pole to the Arctic Circle and nearby the North Pole.
jmotivator says:
Indeed. In South Africa there are extensive fossil beds wherein the fungi went rampant. It appears the forests were felled in a continental sizeed catastrophe, and the fungi spores feasted on the unprecedented banquet of rotting trees.
Professor Lynn Rothschild discusses what extremophiles are, why they are important, and how they are applicable to the evolution of life, what else might be out there, and the future of life.
http://youtu.be/wjHEHjTP8PY
“The Permian Extinction, happened later when temperatures fell by up to 8.0C and it was caused by the Siberian Traps volcanoes. A new study published recently shows this point.”
…and the lack of sunlight caused vegetation to collapse, and the warm seas had boiled off gases such as CO2, O2, CH4, and so forth. The result being large gaps in the food chain and extinctions.