The prevailing theory (on Dino extinction) is said to be a comet/meteor strike, evidenced in the KT Iridium layer, found worldwide. This study though suggests that even though CO2 was high during the Cretaceous, it could still turn cold abruptly. Obviously a stronger forcing of some kind operated then.
Image above: more info
From a Plymouth University Press Release
Scientists identify freezing times for Cretaceous dinosaurs
Summary
Further detail
The drop is estimated to have occurred some 137 million years ago during a time when dinosaurs roamed the Earth, and would have seen the islands fall from an average of 13 degrees centigrade (ocean temperature) to as low as four degrees.
The findings, which were published in the journal Geology and featured as a highlight in Nature Geoscience, will further contribute to the debate over climate change as they appear to contradict the common model which links high levels of Carbon Dioxide (CO2) – as recorded in the Cretaceous era – with reduced polar ice caps.
Despite being located in the Arctic Circle, Svalbard was home to numerous species of dinosaur and was typically characterised by warm, shallow seas and swamps.
But the research team, led by Dr Gregory Price of the University of Plymouth, found evidence in fossils and carbonate materials preserved in marine rocks in the region of a transient shift to cooler glacial conditions around 137 million years ago.
Dr Price said: “At certain times in the geological past, the world has been dominated by greenhouse conditions with elevated CO2 levels and warm Polar Regions, and hence, these are seen as analogues of future global climate.
“But this research suggests that for short periods of time the Earth plunged back to colder temperatures, which not only poses interesting questions in terms of how the dinosaurs might have coped, but also over the nature of climate change itself.”
Dr Price, along with Dr Elizabeth Nunn, of Johannes Gutenburg Universitat in Mainz, Germany, first visited Svalbard in 2005 to collect fossils and samples, in an area famed for a number of paleontological discoveries, including giant marine reptiles such as pliosaurs and icthyosaurs.
The samples were analysed back in Plymouth and prompted return trips to the area to gather more evidence.
“The flourishing of the dinosaurs and a range of other data indicates that the Cretaceous period was considerably warmer and boasted a high degree of CO2 in the atmosphere,” said Dr Price.
“But over a period of a few hundred or a few thousand years, ocean temperatures fell from an average of 13 degrees centigrade to between eight and four degrees.
“Although a short episode of cool polar conditions is potentially at odds with a high CO2 world, our data demonstrates the variability of climate over long timescales.”
Bajan (15:59:21) :
“I remember some Attenborough TV series years ago, in which he explained that the ambient temperature in which a reptile’s egg was incubated determined the sex of the hatchling.”
Bajan, thats quite an original idea. Never seen this as a theory on dinosaur extintion before!
Good thinking.
John H (20:21:42) :
No. Most of the Deccan volcanism was aerial. And it started long before the end of the Cretaceous, and it did not wipe out dinosaurs even in India, there are dinosaurs in the intertrappan beds that formed between eruptions.
Also there was vastly larger submarine eruptions in the mid-Cretaceous when the huge Ontong Java basalt plateau (5 million square kilometers) formed on the bottom of the Pacific in a remarkably short time. This does seem to have had large scale effects on the ocean (Ocean Anoxic Event (OAE) 1, is probably related), but there was no major extinction and the huge quantities om CO2 released into the ocean (and ultimately the atmosphere) did not cause any catastrophe.
I need to read more. What’s here is insufficient and makes the project sound like pure crap.
Mike Lorrey (14:59:45) :
“well, yes, of course. The sun was 30% dimmer back then than at present.”
What do you mean by “back then”? The sun was 30% dimmer 3-4 billion years ago, but by the Cretaceous (150-60 million years ago) its output was not much different than today.
The palaeo history of temperature and CO2 makes the idea of CO2 forcing of climate an absurdity. That AGWers snatch at a dim sun as a fig leaf, and indeed that the CO2 AGW “theory” has any credibility at all, is a sad and disturbing reflection on science, journalism and human society.
What is actually known about the demise of the dinosaurs is the following:
a) there was a large asteroid impact around 65 m y a
b) no dinosaur fossils have so far been found above the iridium layer
The conclusion that the asteroid “killed” the dinosaurs is easy to come to, but there are still many questions that have to be answered. If it did kill the dinosaurs, why did it not kill the birds, the crocodiles, the snakes, the turtles, the mammals, the fish etc.?
Maybe the large dinosaurs were already extinct when the asteroid hit? Maybe there were large dinosaurs (or small ones!) even after the event, but we just have not found any fossils yet?
The last chapter in this story has not been written yet …
Interesting research, it never fails to amaze me at the arrogance we accept as truth, when we know so little.
Doesn’t this mean 2000+ppm CO2 made really big plants and really big dinosaurs to eat them?
But further — If the AGW positive feedback theory is correct, and the climate will ‘lock up’ with too much CO2, never recover and we are all going to fry because of the mythical positive feedback, then why haven’t we and the dinosaurs all fried? CO2 was some 2000+ ppm during the Cretaceous time period, surely past the point earth will never recover from.
Yet here we are. Do you sense something is wrong with the “mythical positive feedback theory”.
If not, then this research contradicts “we are all going to fry” if one more ppm goes into the atmosphere. Someone needs to rethink their claims.
Emphasis mine …
JimBob (18:42:57)
“How do we know if they were warm-blooded or cold-blooded? How do we know they didn’t have lungs like a modern reptile?”
Edith Schachner’s article I referred to above showed convincingly that essentially all dinosaurs had the rigid avian type lung characterised by ribs branching in two at the junction with the vertebrae, and some other features. They also had extensive air sacs in bones needed for the avian style one-way air circulation (much more efficient). It was clearly not the hepatic piston type lung of the crocodile, and the fact that the lung was rigid excluded the mammalian tidal lung also.
Unlike us but again like birds (recall your last roast chicken / turkey) dinosaur ribs go all the way along the thorax, no belly-dancing for dinosaurs or six-packs. A rigid thorax with no soft regions.
BTW some rare fossils of dinosaurs e.g. in China do include soft tissue not only bone, in special circumstances of preservation in mud. Recall the Archaeopteryx in Germany, complete with feathers.
Having this hyper-efficient avian type lung also rather answers the question of thermal stragety – such a lung makes no sense in a cold-blooded animal.
Of course I agree that science is not settled. I was interested in dinosaurs in my teens and read a whole book on the question “hot or cold blooded?” Human nature sadly seems more settled – political systems including imposed belief systems have always arisen in human society with no sign of change.
Climate change is natural. Belief in human caused global warming is a mistake. Average global temperatures for at least 114 years and counting have been accurately calculated (coefficient of determination, R2 = 0.86). There was no need whatsoever to include the effects of change to the level of atmospheric carbon dioxide or any other greenhouse gas. See how and eye-opening graphics at http://climaterealists.com/attachments/database/corroborationofnaturalclimatechange.pdf
Sean Peake says:
“The inference in the PR release statement, “Despite being located in the Arctic Circle, Svalbard was home to numerous species of dinosaur and was typically characterised by warm, shallow seas and swamps” is a bit disingenuous since Svalbard thousands of miles to the south of the Arctic Circle at that time.”
Sean, I don’t think you are correct about “thousands” of miles but, if your were, wouldn’t it be that much more remarkable to have a big freeze that far south.
R. Gates says:
April 26, 2010 at 3:57 pm
“Interesting, but not sure how there is anything contradictory here, or especially revealing. It was warm, CO2 was high, and then a major global event (i.e. large comet or asteroid strike) caused a major climate change for a period of time. I don’t see must of interest of either the AGW supporter or AGW skeptics grist mill here. Barely worth my eyesight actually…”
Your eyesight might need adjustment. The big chill referred to was 137mya when CO2 was quite high and the comet was safely somewhere else. The comet hit 70million years later – there are two events here, both of which represent natural climate change.
JimBob says:
April 26, 2010 at 6:42 pm re: how we know the dinos were warm-blooded.
It was actually a French mathematician that calculated that a massive dinosaur couldn’t get his core body temperature heated up quickly enough from the outside by the sun to get him going in the morning (forgot his name).
phlogiston says:
April 26, 2010 at 2:00 pm
There was a compendium issue of palaeontology in the Anatomical Record in 2009 which included a fascinating paper…
___________________________________
Thank you for the fascinating information. The information has certainly changed since that last time I did a lot of reading on dinosaurs.
L Nettles says:
Was there a Gulf Stream 140 million years ago? Where was Svalbard?
There was no Gulf Stream ‘cos there was no American Gulf 140 million years ago. It was only forming 80 m years ago. By about 3 million years ago, an isthmus formed between North and South America. For what it’s worth, my view is that this was the cause of the earth cooling and climate variability becoming so erratic.
http://www.uwgb.edu/dutchs/platetec/plhist94.htm#150my
Sea levels fluctuated during the middle to late cretaceous indicating warming and cooling temperture changes were common. What we call dinosaurs were not cold blooded but were intolarant of the cold. Some developed feathers that allowed them to range over a wider degree of temerature zones.
Just a thought but I wondered if there is evidence that the K-T event actually set off the Deccan Traps? A major impact must have seismic consequences. If so, the K-T event set in motion effects that impacted climate for an extended age. Is this what saw off the already dwindling Dinosaur population and allowed the emergence of mamals? In any case CO2 must have had a pretty minor role. Sorry Al. Pack up your Carbon Credits and go home. We’re all waiting for Yellowstone to blow.
Gore was here in Denver yesterday.
Gore tells foundations: Climate strides in your hands
By Bruce Finley
The Denver Post
Posted: 04/27/2010 01:00:00 AM MDT
My daughter observed that as an example of natural selection, the snake in a roomful of people fails the test of common sense. I reminded her that Gore is an evangelist for his religion. Getting the Biblical reference in there allows him to hedge his bets, covering natural selection and religion all in one failed metaphor.
He got a standing ovation.
Gail Combs says:
April 27, 2010 at 11:36 am
It is Anat. Rec. vol 292 no. 9, Sept 2009. I picked it up at an orthopedic conference recently, Wiley-Blackman were giving away free copies.
“We need to find the aliens that murdered our dinosaurs and make sure we get them before they get us. It all makes sense now. They may have already started their attack, there’s four times as many polar bears as there were 20 years ago and they are going extinct! PROOF OF ALIEN ATTACK! We must protect our polar bears, ourselves, and avenge the dinosaurs!”
David, the polar bears are not going extinct, they’re increasing. Don’t you get it?? The aliens have landed and taken the form of polar bears!
“So any AGW we leaked into the past would’ve missed”
Whoa. Stand by for a lawsuit from another planet for the AGW and CO2 that we generated 137 million years ago.