Skip to comments.Dinosaurs' climate shifted too, reports show
Posted on 09/25/2006 4:15:43 AM PDT by Pharmboy
Caption: IU Bloomington geochemist Simon Brassell (right), Penn State sedimentologist Michael Arthur (middle), and Tohoku Univ. sedimentologist Harumasa Kano (left) inspect an ancient shale aboard the JOIDES Resolution research vessel.
BLOOMINGTON, Ind. -- Ancient rocks from the bottom of the Pacific Ocean suggest dramatic climate changes during the dinosaur-dominated Mesozoic Era, a time once thought to have been monotonously hot and humid.
In this month's Geology, scientists from Indiana University Bloomington and the Royal Netherlands Institute for Sea Research present new evidence that ocean surface temperatures varied as much as 6 degrees Celsius (about 11 degrees Fahrenheit) during the Aptian Epoch of the Cretaceous Period 120 million years ago.
The finding is relevant to the ongoing climate change discussion, IUB geologist Simon Brassell says, because it portrays an ancient Earth whose temperatures shifted erratically due to changes in carbon cycling and did so without human input.
"Combined with data from the Atlantic, it appears clear that climate changes were taking place on a global scale during this time period," said Brassell, who led the study.
A previous study from an Atlantic Ocean site had suggested a changeable climate around the same time period. But it was not known whether the Atlantic data indicated regional climate change unique to the area or something grander.
"We had virtually no data from the middle of the largest ocean at that time period," Brassell said. "The data we collected suggest significant global fluctuations in temperature."
As part of the National Science Foundation's Ocean Drilling Project, the geoscientists voyaged in 2001 to Shatsky Rise, a study site 1,600 kilometers (1,000 miles) east of Japan and 3,100 meters below the ocean surface. Shatsky Rise is known to have formed at the end of the Jurassic Period immediately prior to the beginning of the Cretaceous, the last period of the Mesozoic Era.
The scientists' vessel, the JOIDES Resolution, is specially outfitted with a drill that can be lowered to the sea floor for the collection of rock samples.
The drill bit was driven 566 meters into Shatsky Rise. Rocks freed by the drill were transported directly to the surface for analysis. The rocks corresponding to early Aptian time were extremely rich in organic material. By analyzing the carbon and nitrogen content of the samples, the geochemists found evidence for changes in carbon cycling and in nitrogen fixation by ocean biological communities associated with changing climate. A special analysis method targeting certain complex carbon-containing molecules provided values for a measurement called TEX86 that revealed mean temperature variations between 30 deg C (86 deg F) and 36 deg C (97 deg F) with two prominent cooling episodes of approximately 4 deg C (7 deg F) in tropical surface temperatures during the early Aptian. By comparison, today's tropical sea surface temperatures typically lie between 29 and 30 deg C.
Brassell says that findings of a changeable climate during the Cretaceous, a time period dominated by dinosaurs and noted for the spread of flowering plants, could influence the current climate change debate.
"One of the key challenges for us is trying to predict climate change," Brassell said. "If there are big, inherent fluctuations in the system, as paleoclimate studies are showing, it could make determining Earth's climatic future even harder than it is. We're learning our climate, throughout time, has been a wild beast."
"Instability in tropical sea surface temperatures during the Early Aptian," Geology vol. 34, no. 10
Worth repeating. I await the MSM discussion of these findings. Al Gore: call yer office.
He can't he's busy trying to determine if his rifle is loaded.
Whenthey find a Fred Flintstone car buried alongside a dinosaur and they find out it has an internal combustion engine, then I will believe that humans cause global warming. Until then i go along with the Mother Nature cyclical theory.
I knew it. The big monsters had SUV's and huge steel plants
Actually, it was Fred Flinstone's fault.
Well, no DUH!
Very clever--nicely done!
Well, they just added some good old fashioned Hoosier common sense (expected, of course, from the only state with a State Casserole).
What happened to the asteroid strike or volcanic activity theories?
Random ping--not for you to ping your lists, just for your interest.
It happened when they elected Ook Bush.
a. Climate fluctuation had nothing to do with the dinosaurs demise and they are not making that argument.
b. The Chixculub 'asteroid strike' is not a theory, but an established fact. The crater is in Yucatan and has been conclusively dated to 65MYA, when the dinosaurs disappeared. That it caused the extinction of just about every critter we know of bigger than about 50 pounds is established by extensive and varied evidence from the geologic record and the fossil record.
To get back on topic, every time I point out to the 'global warming' nuts that the earth was so warm during the Mesozoic that BOTH Antarctica and Alaska (which were in about the same positions as they are today on the globe) supported temperate rainforests, they usually end the discussion (or, in the case of one 'green' blogger, repeatedly erase my posts on their website.....
More evidence of climate fluctuation before SUVs.
Well, duh! Dinosaurs are made out of....petroleum! Obviously they would produce climate change. There was probably even a Bush family dinosaur cabal back then.
Just can't have those pesky facts hanging around cluttering things up, now can we? LOL
What a nightmare, it would have been to be in Goron's platoon.
Of course that was no problem as he really wasn't in a platoon.
It shouldn't be a surprise that changes in carbon cycling drive climate.
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