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Paleoclimate Thread

Re: Paleoclimate Thread

Unread postby dissident » Wed 01 Jul 2015, 17:20:00

BTW, read the comments below the linked article. You see a bunch of amateurs using "proof by sound of plausibility" to claim the meteor triggered volcanism. These people should go and buy a clue. Any volcanism from the meteor would be in the region of its impact and not locate on the other side of the plant. Also, volcanism is a slow process and not some rapid instability which can be triggered off by a meteor impact. The Deccan traps did not need the meteor to form.
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Re: Paleoclimate Thread

Unread postby Apneaman » Wed 01 Jul 2015, 17:43:48

So what did-in the dinosaurs? A murder mystery…
Posted on 12 March 2015 by howardlee

Scientists have assembled a slew of new forensic evidence – from high-resolution dates to microscopic fossils – to prosecute the dino-killer. Their indictment has worrying implications for us.

Everyone knows that the dinosaurs were wiped out - along with about 70% of all species - by a massive asteroid slamming into Mexico, right? Well, not so fast. Like a good murder-mystery, a steady drip of evidence and some major new revelations have implicated another suspect – were they in it together or is one innocent?

http://www.skepticalscience.com/So-what ... saurs.html
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Re: Paleoclimate Thread

Unread postby Apneaman » Wed 01 Jul 2015, 17:44:32

A BC Megadrought? We've Had Them Before

What the 'xerothermic' age tells us about a drier future.

http://thetyee.ca/Opinion/2015/03/11/BC-Megadrought/
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Re: Paleoclimate Thread

Unread postby vox_mundi » Wed 01 Jul 2015, 17:51:32

dissident wrote:BTW, read the comments below the linked article. You see a bunch of amateurs using "proof by sound of plausibility" to claim the meteor triggered volcanism. These people should go and buy a clue. Any volcanism from the meteor would be in the region of its impact and not locate on the other side of the plant. Also, volcanism is a slow process and not some rapid instability which can be triggered off by a meteor impact. The Deccan traps did not need the meteor to form.

I disagree ...

The physics of Antipodal Impact Shock Dynamics has been around for over 20 years.

A good primer ...

http://www.newgeology.us/presentation35.html

http://www.princeton.edu/main/news/arch ... /90/32S94/

for what it's worth, we also see this in forensic analysis of blows to the head. The brain will show an internal injury antipodal to the original blow.

It also comes into play when you detonate the "pit" in a thermonuclear weapon.
Last edited by vox_mundi on Wed 01 Jul 2015, 18:11:40, edited 1 time in total.
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Re: Paleoclimate Thread

Unread postby dissident » Wed 01 Jul 2015, 18:07:49

vox_mundi wrote:
dissident wrote:BTW, read the comments below the linked article. You see a bunch of amateurs using "proof by sound of plausibility" to claim the meteor triggered volcanism. These people should go and buy a clue. Any volcanism from the meteor would be in the region of its impact and not locate on the other side of the plant. Also, volcanism is a slow process and not some rapid instability which can be triggered off by a meteor impact. The Deccan traps did not need the meteor to form.

I disagree ...

The physics of Antipodal Impact Shock Dynamics has been around for over 20 years.

A good primer ...

http://www.newgeology.us/presentation35.html

http://www.princeton.edu/main/news/arch ... /90/32S94/

for what it's worth, we also see this in forensic analysis of blows to the head. The brain will show an internal injury antipodal to the original blow


Shock waves will not melt rock. If they did then you are talking about a planet destroying impact. As I said, volcanism is not like earthquakes. Rock does not melt spontaneously due to some perturbation. India was plowing into Asia during that epoch giving rise to the Himalayas. That is the process responsible for the Deccan traps. Do some research first.

These rock-melting shockwaves lasted 10,000s of thousands of years did they? Please.

https://en.wikipedia.org/wiki/Deccan_Traps

No meteor theory for the Deccan traps except in the minds of random uneducated internet users who got their education via Hollywood cheese.
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Re: Paleoclimate Thread

Unread postby vox_mundi » Wed 01 Jul 2015, 18:25:10

Focused shock waves fracture rock they don't melt it. If you fracture the crust over a 100-200 mile region you've essentially created a super caldera. Magma will follow the path of least resistance.

To picture what an antipodal shock would look like imagine the ground rising 2-3000 ft over a huge region then settling back. With cracks like that you can't stop the magma from coming out.

read the link

dissident wrote: India was plowing into Asia during that epoch giving rise to the Himalayas. That is the process responsible for the Deccan traps. Do some research first.

Yes. Please do.

The India landmass hadn't reached the Eurasian plate till 30-50M bp thus the Himalayan uplift had nothing to do with the Deccan Traps by close to 30 million years.

http://www.princeton.edu/main/news/arch ... /14/62G75/

What about the Shiva crater complex? https://en.m.wikipedia.org/wiki/Shiva_crater

What about the Réunion hotspot?
https://en.m.wikipedia.org/wiki/R%C3%A9union_hotspot

There's plenty of room for everybody.
Last edited by vox_mundi on Wed 01 Jul 2015, 19:11:10, edited 1 time in total.
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Re: Paleoclimate Thread

Unread postby Synapsid » Wed 01 Jul 2015, 18:27:10

There have been three major episodes of mass extinction in the last quarter of a billion years:

end of the Permian, the most extensive, about 252 million years ago;

end of the Triassic, about 200 million years ago;

end of the Cretaceous, 65 million years ago.

Each has occurred during long periods of flow-basalt volcanism on a huge scale. The reconstructed area of the end-Permian flows is comparable to the area of the lower 48 states west of the Mississippi. Emissions, during the volcanism, of CO2 and sulfur oxides, episodically over many hundreds or thousands of years, would have caused oceanic and atmospheric changes too rapid for natural selection to enable most organisms to adapt, judging from the demise of whole ecosystems not just species, a scale of loss that is what is called a mass extinction.

Mass extinctions are recorded in the fossil record and that is contained almost entirely in sedimentary rocks. The periods of flood-basalt extrusion could last for hundreds of millennia but there were intervening times, ranging from a few years to thousands maybe tens of thousands, that allowed landscapes to develop and marine environments to stabilize, settings in which sediments could accumulate that contain the remains of organisms that lived during the pauses in volcanism. The extinction at the end of the Cretaceous is recorded in sedimentary rocks interbedded between basalts of the Deccan Traps, in India, telling us that the basalts below the extinction level preceded the extinction and the basalts above that level postdate the extinction--in other words, the mass extinction occurred long after the volcanism began, about 750 000 years after, if memory serves, and well before it ended. Had there been no asteroid impact or impacts there likely would have been extensive extinction anyway, just as there had been at the end of the Permian and of the Triassic. As to asteroid impact occurring during a major flood-basalt episode, Walter Alvarez, a leading figure in the work at Gubbio on the clay layer and one of the originators of the impact/extinction hypothesis, said "Once in a while you get a really bad day."

There is no evidence of impacts associated with the end-Permian or end-Triassic extinctions.
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Re: Paleoclimate Thread

Unread postby dohboi » Thu 09 Jul 2015, 20:52:20

Why the Earth’s past has scientists so worried about sea level rise
By Chris Mooney

http://www.washingtonpost.com/news/ener ... evel-rise/
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Re: Paleoclimate Thread

Unread postby dissident » Thu 09 Jul 2015, 22:08:09

dohboi wrote:Why the Earth’s past has scientists so worried about sea level rise
By Chris Mooney

http://www.washingtonpost.com/news/ener ... evel-rise/


So much waffle. The most obvious inference is that one gets 6 meters of sea level rise with relatively little warming. So looking at current sea level rise and thinking that "we are not committed" to six meters is total BS. We are committed for sure. The article also seems to think that global warming can be held at 1.5 C. That is must be some kind of joke. We are already guaranteed over 2 C with current CO2 levels.

In fact, the closest analogue is the mid-Pliocene with its 400 ppmv of CO2. And in this case 6 m is some lower bound and the actual sea levels were probably much much higher.
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Re: Paleoclimate Thread

Unread postby Tanada » Thu 09 Jul 2015, 23:01:20

dissident wrote:
dohboi wrote:Why the Earth’s past has scientists so worried about sea level rise
By Chris Mooney

http://www.washingtonpost.com/news/ener ... evel-rise/


So much waffle. The most obvious inference is that one gets 6 meters of sea level rise with relatively little warming. So looking at current sea level rise and thinking that "we are not committed" to six meters is total BS. We are committed for sure. The article also seems to think that global warming can be held at 1.5 C. That is must be some kind of joke. We are already guaranteed over 2 C with current CO2 levels.

In fact, the closest analogue is the mid-Pliocene with its 400 ppmv of CO2. And in this case 6 m is some lower bound and the actual sea levels were probably much much higher.


Indeed, and what is even worse IMO is they completely ignore all the other GHG emissions humans are making. IIRC we are currently at 460 ppmv CO2equivalent when you add in the methane, ammonia, tetra-fluorides, NOx, and the traces of Sulfur Hexafluoride and many other trace chemicals. Some of these would abate fairly quickly like Methane, but Sulfur Hexafluoride and Nitrogen Trifluoride are used as neutral coolants in chip manufacturing for computers. A little bit gets released for every electronic device manufactured from your cell phone on up through your 72 inch plasma TV set, and they have atmospheric lifetimes in the 10,000 year span range.
https://en.wikipedia.org/wiki/Nitrogen_ ... nhouse_gas
https://en.wikipedia.org/wiki/Sulfur_he ... nhouse_gas
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Re: Paleoclimate Thread

Unread postby dohboi » Sun 12 Jul 2015, 18:15:24

Good points, T and dis.

Now this: http://www.onearth.org/earthwire/coral- ... ocialmedia

Ghost of Climates Past
A coral skeleton reveals weather patterns from 500 years ago.


Scientists at Stanford University are channeling their inner Superman by using X-ray vision to fight bad guys climate change. Their synchrotron, one of the most powerful X-ray machines in the world, can reveal chemicals deep within coral skeletons that illustrate what the weather was doing at different points in the animal’s long life. The new technique can show ocean temperatures and precipitation patterns from 500 years ago.

For comparison, detailed written weather records only go back about 150 years. That’s why paleoclimatologists (who study the climate of way back when) are taking clues from nature that’s been around for a while, like tree rings, volcanic ash, ice cores, and, now, coral. By reconstructing the climate of the past, they hope to prepare us for the one in our future.
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Re: Paleoclimate Thread

Unread postby Keith_McClary » Fri 24 Jul 2015, 00:10:56

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Re: Paleoclimate Thread

Unread postby dohboi » Fri 24 Jul 2015, 07:34:28

https://www.newscientist.com/article/dn ... te-change/

[b]Megafauna extinction: DNA evidence pins blame on climate change[/b]

“Climate is the thing that is constantly sending these species out through time without humans even being involved,” says Cooper. “That’s the bit that is really completely new.”

The team were surprised by another finding that emerged: it wasn’t the long cold periods that wiped out megafauna, as some have suggested – it was warming.

“What we found, which we were staggered by: no matter how we analysed the data, abrupt warmings drove the extinctions or the replacements,” says team member Chris Turney of the University of New South Wales in Sydney, Australia.

It is most likely that warming was such a killer because it arrives rapidly – temperatures change far more abruptly than they do at the onset of a cooling period, says Cooper.
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Re: Paleoclimate Thread

Unread postby Keith_McClary » Sat 05 Dec 2015, 02:41:52

Study undercuts idea that 'medieval warm period' was global
December 4, 2015
Gifford Miller, a paleoclimatologist at the University of Colorado, called the paper "a coup de grace on the Medieval Warm Period." Miller said it shows "with great clarity of evidence" that "the idea of a consistently warm Medieval period is certainly an oversimplification and of little utility."
Astrid Ogilvie, a climate historian currently based at Iceland's Akureyri University, said the study "shows that the climate is clearly more complicated and variable than people earlier assumed." As for the Vikings, the climate story has been dimming for some time, she said. "I do not like the simplistic argument that the Greenland people went there when it was warm, and then 'it got cold and they died'," she said. "I think the Medieval Warm Period has been built on many false premises, but it still clings to the popular imagination."
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Re: Paleoclimate Thread

Unread postby Tanada » Sat 05 Dec 2015, 11:28:00

I don't know if I would classify the MWP as PALEO, but I can't think of a better thread to move it to either.

The problem is scientific research is divided on the MWP, some far flung places on the globe were all effected during that time, but many others were not. It is as if the MWP was not a Global phenomenon, but it also wasn't just a European effect either.
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Re: Paleoclimate Thread

Unread postby Keith_McClary » Sat 05 Dec 2015, 17:43:48

Tanada wrote:I don't know if I would classify the MWP as PALEO, but I can't think of a better thread to move it to either.

Paleoclimatology data are derived from natural sources such as tree rings, ice cores, corals, and ocean and lake sediments. These proxy climate data extend the archive of weather and climate information hundreds to millions of years. The data include geophysical or biological measurement time series and some reconstructed climate variables such as temperature and precipitation.

https://www.ncdc.noaa.gov/data-access/p ... ology-data
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Re: Paleoclimate Thread

Unread postby Keith_McClary » Wed 06 Jan 2016, 23:29:47

Current pace of environmental change is unprecedented in Earth's history
January 5, 2016
University of Bristol Cabot Institute researchers and their colleagues today published research that further documents the unprecedented rate of environmental change occurring today, compared to that which occurred during natural events in Earth's history.
The research, published online on 4 January in Nature Geosciences reconstructs the changes in atmospheric carbon dioxide (pCO2) during a global environmental change event that occurred about 120 Million years ago. New geochemical data provide evidence that pCO2 increased in response to volcanic outgassing and remained high for around 1.5-2 million years, until enhanced organic matter burial in an oxygen-poor ocean caused areturn to original levels.
Lead author Dr David Naafs explained: 'Past records of climate change must be well characterised if we want to understand how it affected or will affect ecosystems. It has been suggested that the event we studied is a suitable analogue to what is happening today due to human activity and that a rapid increase in pCO2 caused ocean acidification and a biological crisis amongst a group of calcifying marine algae. Our work confirms that there was a large increase in pCO2. The change, however, appears to have been far slower than that of today, taking place over hundreds of thousands of years, rather than the centuries over which human activity is increasing atmospheric carbon dioxide levels. So despite earlier claims, our research indicates that it is extremely unlikely that widespread surface ocean acidification occurred during this event.'
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Re: Paleoclimate Thread

Unread postby PrestonSturges » Thu 07 Jan 2016, 13:28:31

This wikipedia article discusses the Eemian interglacial period from 130,000 to 115,000 years ago. Temperatures were about 2 degrees C warmer, there were hippos in the Thames, and trees grew nearly to the shore of the Arctic. It sounds pretty mellow, except that sea levels were 20 to 30 feet higher, which today (and the next 50+ years) will displace billions of people. Evidence of these higher sea levels are everywhere, such as the coral reefs that created the Bahamas before the water fell again during the last Ice Age.

https://en.wikipedia.org/wiki/Eemian
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Re: Paleoclimate Thread

Unread postby dohboi » Thu 07 Jan 2016, 16:31:48

First, we are not going to stop at 2 degrees.

Second, it is the pace of change, fastest in the history of complex life on the planet, that is going to be the real killer. The only difference between someone gently handing you a bowling ball and putting the same ball in a cannon and blasting a whole through your torso is rate of change. That is what we are doing to the earth now.

Also, displacing billions of people is, I would say, kind of a big deal. And in the mean time, disruptions from desertification and inundation will certainly prompt wars and deeply disruptive mass migrations of humans, something we are already seeing now (but was not much of a problem for the Eemian).

Finally, fully modern humans hadn't even evolved before the end of the Eemian. Certainly civilization developed under very, very different climatic circumstances. Just because it was nice for some of the critters over 100 thousand years ago doesn't mean it will be nice for creatures and societies like ours that evolved and developed under vastly different circumstances and have never survived global temperatures of those levels.
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Re: Paleoclimate Thread

Unread postby onlooker » Mon 18 Jan 2016, 10:43:02

http://www.dailykos.com/story/2013/10/4 ... -000-Years
The Oceans are Dying: Oxygen is Depleting, Acidity Rising at Fastest Rate in 300,000,000 Years
We seem to be rapidly creating conditions by spewing so much CO2 similar to those that existed and were the catalyst for the Permian Mass Extinction event some 200 million years ago.
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