From the UNIVERSITÉ DE GENÈVE
The cold exterminated all of them
Through age determinations that are using the radioactive decay of uranium, scientists have discovered that one of the greatest mass extinctions was due to an ice age and not to a warming of Earth temperature
The Earth has known several mass extinctions over the course of its history. One of the most important happened at the Permian-Triassic boundary 250 million years ago. Over 95% of marine species disappeared and, up until now, scientists have linked this extinction to a significant rise in Earth temperatures. But researchers from the University of Geneva (UNIGE), Switzerland, working alongside the University of Zurich, discovered that this extinction took place during a short ice age which preceded the global climate warming. It’s the first time that the various stages of a mass extinction have been accurately understood and that scientists have been able to assess the major role played by volcanic explosions in these climate processes. This research, which can be read in Scientific Reports, completely calls into question the scientific theories regarding these phenomena, founded on the increase of CO2 in the atmosphere, and paves the way for a new vision of the Earth’s climate history.
Teams of researchers led by Professor Urs Schaltegger from the Department of Earth and Environmental Sciences at the Faculty of Science of the UNIGE and by Hugo Bucher, from the University of Zürich, have been working on absolute dating for many years. They work on determining the age of minerals in volcanic ash, which establishes a precise and detailed chronology of the earth’s climate evolution. They became interested in the Permian-Triassic boundary, 250 million years ago, during which one of the greatest mass extinctions ever took place, responsible for the loss of 95% of marine species. How did this happen? for how long marine biodiversity stayed at very low levels ?
A technique founded on the radioactive decay of uranium
Researchers worked on sediment layers in the Nanpanjiang basin in southern China. They have the particularity of being extremely well preserved, which allowed for an accurate study of the biodiversity and the climate history of the Permian and the Triassic. “We made several cross-sections of hundreds of metres of basin sediments and we determined the exact positions of ash beds contained in these marine sediments,” explained Björn Baresel, first author of the study. They then applied a precise dating technique based on natural radioactive decay of uranium, as Urs Schaltegger added: “In the sedimentary cross-sections, we found layers of volcanic ash containing the mineral zircon which incorporates uranium. It has the specificity of decaying into lead over time at a well-known speed. This is why, by measuring the concentrations of uranium and lead, it was possible for us to date a sediment layer to an accuracy of 35,000 years, which is already fairly precise for periods over 250 million years.”
Ice is responsible for mass extinction
By dating the various sediment layers, researchers realised that the mass extinction of the Permian-Triassic boundary is represented by a gap in sedimentation, which corresponds to a period when the sea-water level decreased. The only explanation to this phenomenon is that there was ice, which stored water, and that this ice age which lasted 80,000 years was sufficient to eliminate much of marine life. Scientists from the UNIGE explain the global temperature drop by a stratospheric injection of large amounts of sulphur dioxide reducing the intensity of solar radiation reaching the surface of the earth. “We therefore have proof that the species disappeared during an ice age caused by the activity of the first volcanism in the Siberian Traps,” added Urs Schaltegger. This ice age was followed by the formation of limestone deposits through bacteria, marking the return of life on Earth at more moderate temperatures. The period of intense climate warming, related to the emplacement of large amounts of basalt of the Siberian Traps and which we previously thought was responsible for the extinction of marine species, in fact happened 500,000 years after the Permian-Triassic boundary.
This study therefore shows that climate warming is not the only explanation of global ecological disasters in the past on Earth: it is important to continue analysing ancient marine sediments to gain a deeper understanding of the earth’s climate system.
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I like explosions as much as anyone, and in the absence of a big P-T astrobleme I like Svensmark’s supernovae best.
Have any super nova remnants been found 200 to 250 million light years from the earth?
According to Svensmark’s 2012 paper (featured at WUWT), Earth gets a heavy shower of gamma-rays every 250-300 million years.
I find this very illuminating.
Nice to see scientists at work. I took the last statement to be an affirmation that science requires constant debate. Never shouting down.
Occam’s razor strikes again.
Seems some comet evidence colored the ice sheet data!?
Whenever there is a mass extinction affecting over 90% of marine species, ocean acidification from volcanic sulfates is the likely cause.
So the hypothesis they develop is that the mass extinction took place during an ice age caused by unusual volcanic activity. Most species died as a consequence of ocean acidification, acid rain, decrease in insolation, and sudden cooling, because we know that ice ages do not cause mass extinctions by themselves. This is usually describe as a volcanic winter. A very big one.
However we still don’t know the cause of the unusual volcanic activity. Could it not be due to another asteroid hitting the Earth like in the K-T extinction? Something like that could very well cause unusual volcanic activity.
And I hate it when they say:
They have discovered evidence that they interpret as due to an ice age in their hypothesis. In science the level of security displayed does not exist. Much less about something that happened 250 million years ago. New evidence could change the way we interpret this event.
Thank you, Javier, for your remarks. I was about to ask how an ice age would cause 90% of marine species to go extinct.
The putative Wilkes Land Crater was suggested as an impact that could have caused the Siberian Traps eruptions, but this conjecture has been thoroughly debunked.
That leaves mantle plume or superplume activity, as is the case with most such volcanism, if not all.
Shocking find: We really don’t know.
OR
Aliens abducted all species during this time.
I’ll go with the latter. (^_^)
An excellent article in many respects. A check on the behaviour of the trace elements from the black shales would indicate a exhalative volcanic regime. This gives rise to a toxic atmosphere. This is all pervasive. and will certainly affect life. If a short term ice age also occurs then the combination would be devastating. In that case hen both marine and terrestrial life is severely affected. It is possible that the mass extinctions at the end of the Ordovician are driven by similar mechanisms. Certainly the work I have done in this age group of black shales point to felsic volcanism as the main driver for unusual sedimentary accumulation possibly leading to mass extinctions. This highly repeatable mechanism also points to the difficulty in having a wandering comet make impact in such a manner as to be the sole cause of mass extinctions.
And if the world cooled, the feedback mechanism that assisted that cooling would have been surface albedo from ice sheets. Surface albedo feedbacks are orders of magnitude greater than CO2 feedbacks, when measured locally.
R
Especially when you remove them.
Clouds. You are assuming no influence on albedo.
Depends on where the ice is. At the poles, ice has very, very, little impact on albedo.
I have often wondered, could massive oceanic strikes produce deadly-enough concussions, to cause mass fish extinctions?
Probably not, as they would need to be mega massive and occur in all depths.
Mmm sounds like a global flood to me
Well done, Fred. For you or any other readers here, see http://creation.com/the-permian-extinction-national-geographic-comes-close-to-the-truth
A very interesting piece of work but there are a couple of points that trouble me. The fact that the report infers that the depositional gap described is stated as representing an interval of 80’000 years might be problematic. Essentially they are saying that there is a discontinuity of 80k years , but it might be more, such things being difficult to be certain of. I admire the confidence to assert intervals of 35k and 80k with accuracy at timescales of 250 my in the past.
Just a quick reading of all the comments shows how problematic the interpretation of all this is at the vast gap of time involved. IT seems that yet again the writing out of the possibility of a cometary impact is at the heart of this because as we know there is no major impact of any comet or asteroid involved in any disruptive event or extinction ever in the Earth’s history. This is because we live on a magic planet which is wholly immune to th celestial events which have left every other body in the solar system looking like it has been used as a pincushion by collisions, but the only bad things that ever happen to our planet are only ever caused by people (preferably either giving off too much CO2, Methane etc or just fornicating too much for the planets alledged sustainability).
Yeah right.
Can’t be true as I’ve been told by lots of folks the science is settled. Besides they’ve got no tree rings.
It largely depends if it’s on the A-list of settled science with politically directed imperatives for revenue reach and the extended list of funded activist groups or if it’s from the B-list of normal science process in overturning conventional understanding. Fortunately medical research is mostly on the B-list.
This direct evidence study blows away the arm waving of presumed mechanisms that typified what came before it. Next step is to study the coral reef fossils of the period with direct core samples.
Wiki says it was the heat that killed off the marine vertebrates when their thermal tolerance was exceeded. Minor discrepancy, sarc
I once attended a talk by Dr. Amy Mainzer, principal investigator on the NEOWISE asteroid-hunting program at JPL. Her talk was fascinating right up the point where she mentioned the Chicxulub meteor strike, widely regarded as the cause of the K-Pg extinction ending the dinosaurs. She said that everyone thinks the blockage of sunlight by the enormous dust cloud put in the atmosphere by the impact caused global cooling. BUT, she said, scientists have found a layer of carbon over the entire globe, all at the geologic time of the asteroid impact. That means that there was a world-wide fire in which all surface vegetation was consumed, putting enormous amounts of carbon dioxide into the atmosphere and causing huge global warming. This, she concluded, means that we need to take global warming seriously.
I almost stopped listening at that point, because that raised a red flag regarding her scientific judgement. Making the leap from a global fire to CO2 induced global warming as the reason for the K-Pg extinction just seemed bizarre to me, especially since no mechanism for warming killing the dinosaurs was put forth in the chain of argument. Before she made that leap, the first thing I thought of was that a fire that wiped out all surface vegetation immediately and completely cut off the bottom of the food chain, and death by starvation of all life depending on that food chain would be inevitable. I still think that’s more plausible than global warming.
Full disclosure: I almost stopped listening, but didn’t; not because of the talk, initially, but because Dr. Mainzer is drop-dead gorgeous. Eventually I got back into the talk, and am glad I did.
It’s appalling how the Carbonisti have polluted science.
The global fires were caused by superheated ejecta returning to earth. No need to invoke CO2 to explain extinctions. The K-P wipeout included global cooling, not warming.
The O-S mass extinction event also was caused by an ice age. No MEE, at least during the Phanerozoic Eon, has been caused by global warming.
Primary causes of the five biggies:
Ordovician-Silurian (~439 Ma): Brief but intense ice age.
Late Devonian (~364 Ma): Volcanism-induced global cooling.
Permian-Triassic (~252 Ma): Volcanism-induced global cooling, leading to a brief but intense ice age.
Triassic-Jurassic (~201 Ma): Volcanism-induced global cooling.
Cretaceous-Paleogene (~66 Ma): Impact- and volcanism-induced global cooling.
Nor do Precambrian MEEs, such as the Great Oxidation Catastrophe and Ediacaran-Cambrian extinctions, appear to have been caused by global warming. Rather, they’re associated with Snowball Earth intervals, ie the most extreme cooling possible.
I’m with you on this Michael. If there was a global fire the heat blast from the impact must have been colossal and probably would have killed off a good part of the animals that went extinct right off even before we got to tidal waves, vegetation fried, dust screening sunlight for days/weeks/months etc. The CO2 would pale into insignificance after these even assuming it was as high as was being supposed. And let’s not forget the follow on eruptions chucking out SiO2 and acid rain like battery acid.
I’d be interested in re-checking any other mass extinctions popularly ascribed to temperature increase, given the stable upper bound in geologic time and the increased prevalence of life in those warmest times versus now.
I mean, if life could barely survive at that upper bound and abounded during Ice Ages, that would be different.