Volcanic Warming Eyed in 'Great Dying'

gollum123 writes "AP writes on an article in the journal Science where an ancient version of global warming may have been to blame for the greatest mass extinction in Earth's history. 'In an event known as the "Great Dying," some 250 million years ago, 90 percent of all marine life and nearly three-quarters of land-based plants and animals went extinct. Researchers think the answer is Massive volcanic flows in what is now Siberia, and believe the extinctions were caused by global warming and oxygen deprivation over long periods of time."

Proves once again

[hsmith]

No one can agree on anything in the science field when it comes to this planet. Earth is more complex than anyone can comprehend or understand, it will outlast humans by a long shot, nothing we will do will kill it.

"mini" Ice Age

[georgep77]

I liked it better in the 70's when all of "pop" science was preaching that we were headed for a mini ice age. This global warming "religeon" is just a little much; espicially since there seems to be so much politic-ing involved.

ho hum
_GP_

Re:Money and Power

[sam_handelman]

The dinosaurs died out 65 million years ago, you twit.

We're talking about the Permian Extinction - which, by the way, no-one actually calls the "Great Dying".

I could tell y'all about it but it would be a duplication of effort. Do yourself a favor and read something:

http://www.bbc.co.uk/education/darwin/exfiles/perm ian.htm [bbc.co.uk]

http://en.wikipedia.org/wiki/Permian_extinction [wikipedia.org]

Full Story

[sandstorming]

FROM: http://story.news.yahoo.com/news?tmpl=story&cid=62 4&ncid=753&e=1&u=/ap/20050121/ap_on_sc/great_dying ----- WASHINGTON - An ancient version of global warming may have been to blame for the greatest mass extinction in Earth's history. In an event known as the "Great Dying," some 250 million years ago, 90 percent of all marine life and nearly three-quarters of land-based plants and animals went extinct. Scientists have long debated the cause of this calamity -- which occurred before the era of dinosaurs -- with possibilities including such disasters as meteor impacts. Researchers led by Peter Ward of the University of Washington now think the answer is global warming caused by volcanic activity. Their findings are reported in Thursday's online edition of the journal Science. They studied the Karoo Basin of South Africa, using chemical, biological and other evidence to relate layers of sediment there to similar layers in China that previous research has tied to the marine extinction at the same period. Studying a 1,000-foot thick section of exposed sediment, Ward's team found evidence of a gradual extinction over about 10 million years followed by a sharp increase in extinction rate that lasted another 5 million years. Ward's team believes the extinctions were caused by global warming and oxygen deprivation over long periods of time. Massive volcanic flows in what is now Siberia brought on the warming while, at the same time, geologic action caused global sea levels to drop, Ward explained in a telephone interview. "Once you expose a huge amount of underwater sediment to the atmosphere, two very bad things happen -- a huge amount of carbon in the sediments is released and also methane. Once (methane) hits the atmosphere it's the most efficient greenhouse gas on the planet," he said. That provided a one-two punch of warming and a decline in oxygen levels, he said. "Some of us have been toying with the idea that dinosaurs evolved to be a low-oxygen adaptation," resulting from this era, Ward said. "We know birds can live at much lower oxygen concentrations than we do, and we and think there were similar lung adaptations in dinosaurs." Currently the atmosphere consists of about 21 percent oxygen, but the addition of gases at that time could have lowered levels to 16 percent or less, Ward said. "If you didn't live on the sea level you didn't live," he commented, reflecting the fact that oxygen concentrations decline with altitude. The result would have been to eliminate half the living space on the planet, said Ward. The more recent mass extinction that killed the dinosaurs -- 65 million years ago -- has been linked to an impact by a large asteroid or comet that struck in an area off the coast of what is now Mexico and left a distinctive layer of dust worldwide. Some researchers have argued that the Great Dying might also have resulted from such an impact, but Ward's team said it could find no evidence for such an event. That doesn't mean there wasn't one, argues Luann Becker of the University of California at Santa Barbara, commenting that "the absence of evidence isn't evidence for absence." Becker, who was not part of Ward's research team, said "they did a nice job of presenting the paleontological data and the stratigraphy, which seem to show some indication of an evolutionary change going on for a prolonged period of time." However, she added, she doesn't believe that addresses the subject of cause and effect. "I think that this is an ongoing discussion," said Becker, who previously reported on a crater off the northwest coast of Australia that shows evidence of a large meteor impact at about the time of the early extinction. Ward's research was funded by the NASA (news - web sites) Astrobiology Institute, the National Science Foundation (news - web sites) and the National Research Foundation of South Africa. ___ On the Net: Science: http://www.sciencemag.org

Vulcanism

[Atrax]

It's certainly not the first time Vulcanism* has been implicated in a mass extinction - the Deccan Traps [nodak.edu], for instance, have been implicated in the KT event that is thought to have wiped out the dinosaurs 65 Million Years ago. There's even a school of thought that says the Chicxulub [arizona.edu] event may have triggered a major convulsion in the Traps - double jeopardy, if you will.

Except that the earth is only about 4000 years old and fossils were put there to test our faith, right?

* I nearly typed 'vulvanism', but that's a different story.

Re:16% oxygen?

[Headw1nd]

You didn't read the article carefully, the great dying happened before the dinosaurs. The researchers are suggesting that the dinosaurs might have come to power specifically because they were adapted to cope with the lower oxygen levels.

Sounds like Yellowstone

[InterStellaArtois]

This is interesting, as just last night I was reading about something similar in Bill Bryson's "A Short History of Nearly Everything" ...

To summarise, Nebraska is well known for its ash deposits - mined for cleaning products like Ajax - but no-one knew where it all came from.

Then in 1971, Mike Voorhies found a mass grave of prehistoric bones - sabre-toothed deer, zebra-like horses etc. - all killed by something big 12 million years ago. They were all buried under volcanic ash up to 3 metres deep.

One problem - no-one knew where all the ash came from.

Now Yellowstone was known to be pretty active, with its geysers, boiling mud-pools etc. but they couldn't find a caldera, ie. an actual volcano cone anywhere in the park.

But fortunately NASA were testing some high altitude photography techniques and decided to take some pictures of Yellowstone, thoughtfully dropping some copies off at the Visitor Centre. It was then that they realised that in fact Yellowstone is ONE BIG CALDERA - i.e. a 'superplume', 9000 square kilometres of crater left from some humungous explosion a long time back.

In Bill Bryson's words, "imagine a pile of TNT about the size of an English county and reaching 13 kilometres into the sky, to about the height of the highest cirrus clouds, and you have some idea of what visitors to Yellowstone are shuffling about on top of".

He goes on, "The Yellowstone eruption of two million years ago put out enough ash to bury New York State to a depth of 20 metres ..."

And then there's the last supervolcano eruption in Toba, in northern Sumatra, 74,000 years ago. Studies of ice cores in Greenland show that at least 6 years of 'volcanic winter' followed, and that humans probably were at the brink of extinction, with maybe only several thousand of us at any one time for thousands of years after (which maybe explains our relative lack of genetic diversity).

Yes, volcanoes are more than fire and magma - every now and then there're some *really* big ones.

Re:16% oxygen?

[garcia]

I read the article "carefully" but I don't agree with their theory on the subject:

"Some of us have been toying with the idea that dinosaurs evolved to be a low-oxygen adaptation," resulting from this era, Ward said. "We know birds can live at much lower oxygen concentrations than we do, and we and think there were similar lung adaptations in dinosaurs."

Yeah, birds can live at lower oxygen levels because they fly at altitude on a regular basis. They also come down to the ground for various reasons. That way they are cross-training at different altitudes and thus able to adapt to varying conditions.

As far as I am aware MOST dinosaurs did not have the ability to fly. And supposedly if you weren't near sea-level you weren't going to live. So, the dinosaurs were not cross-training at differing altitudes and probably did not gain the same sort of breathing abilities that birds did.

I think it was quite a leap for the scientists in this article to make. Then again IANAS.

Re:dinosaurs with cars

[Anonymous Coward]

You laugh. A friend of mine has a daughter who did her PhD thesis on the effects of termite flatulence on the ozone layer. Junk science at its best.

Newsweek April 28, 1975: The Cooling World

[glrotate]

here are ominous signs that the Earth's weather patterns have begun to change dramatically and that these changes may portend a drastic decline in food production- with serious political implications for just about every nation on Earth. The drop in food output could begin quite soon, perhaps only 10 years from now. The regions destined to feel its impact are the great wheat-producing lands of Canada and the U.S.S.R. in the North, along with a number of marginally self-sufficient tropical areas - parts of India, Pakistan, Bangladesh, Indochina and Indonesia - where the growing season is dependent upon the rains brought by the monsoon.

The evidence in support of these predictions has now begun to accumulate so massively that meteorologists are hard-pressed to keep up with it. In England, farmers have seen their growing season decline by about two weeks since 1950, with a resultant overall loss in grain production estimated at up to 100,000 tons annually. During the same time, the average temperature around the equator has risen by a fraction of a degree - a fraction that in some areas can mean drought and desolation. Last April, in the most devastating outbreak of tornadoes ever recorded, 148 twisters killed more than 300 people and caused half a billion dollars' worth of damage in 13 U.S. states.

To scientists, these seemingly disparate incidents represent the advance signs of fundamental changes in the world's weather. Meteorologists disagree about the cause and extent of the trend, as well as over its specific impact on local weather conditions. But they are almost unanimous in the view that the trend will reduce agricultural productivity for the rest of the century. If the climatic change is as profound as some of the pessimists fear, the resulting famines could be catastrophic. "A major climatic change would force economic and social adjustments on a worldwide scale," warns a recent report by the National Academy of Sciences, "because the global patterns of food production and population that have evolved are implicitly dependent on the climate of the present century."

A survey completed last year by Dr. Murray Mitchell of the National Oceanic and Atmospheric Administration reveals a drop of half a degree in average ground temperatures in the Northern Hemisphere between 1945 and 1968. According to George Kukla of Columbia University, satellite photos indicated a sudden, large increase in Northern Hemisphere snow cover in the winter of 1971-72. And a study released last month by two NOAA scientists notes that the amount of sunshine reaching the ground in the continental U.S. diminished by 1.3% between 1964 and 1972.

To the layman, the relatively small changes in temperature and sunshine can be highly misleading. Reid Bryson of the University of Wisconsin points out that the Earth's average temperature during the great Ice Ages was only about seven degrees lower than during its warmest eras - and that the present decline has taken the planet about a sixth of the way toward the Ice Age average. Others regard the cooling as a reversion to the "little ice age" conditions that brought bitter winters to much of Europe and northern America between 1600 and 1900 - years when the Thames used to freeze so solidly that Londoners roasted oxen on the ice and when iceboats sailed the Hudson River almost as far south as New York City.

Just what causes the onset of major and minor ice ages remains a mystery. "Our knowledge of the mechanisms of climatic change is at least as fragmentary as our data," concedes the National Academy of Sciences report. "Not only are the basic scientific questions largely unanswered, but in many cases we do not yet know enough to pose the key questions."

Meteorologists think that they can forecast the short-term results of the return to the norm of the last century. They begin by noting the slight drop in overall temperature that produces large numbers of pressure centers in the upper atmosphere. These break up the smooth flow of west

Re:16% oxygen?

[Atrax]

OK. yeah. sort of right. for a given value of right.

It's the equivalent of teaching newtonian gravity at high school so that later you can learn einsteinian gravity at university, and then demolish the whole thing in your PhD thesis.

the fringes of the atmosphere are thinner in oxygen than the lower reaches. of course for practical purposes (Everest/Chomolungma) there's less difference in percentage than higher up, and pressure is the overriding factor.

OK, OK, I'm Anal Retentive. sue me.

Re:16% oxygen?

[Wyatt Earp]

No, but reptiles are more efficent than mammels or insects are with thier breathing. An Iguana for example can go 15-20 minutes underwater.

It's not about cross-training, it's about how respiratory systems work. And since birds came out of Dinosaurs, it's likely that thier respiratory system is more like birds than Mammals are since Mammals split off before the Dinosaurs evolved and for that matter, the Reptiles crawling around right now evolved before the evolution of dinosaurs are pretty much stayed where they are.

So, lets take a look at Aves.

http://www.biology.eku.edu/RITCHISO/birdrespirat io n.html

"The avian respiratory system delivers oxygen from the air to the tissues and also removes carbon dioxide. In addition, the respiratory system plays an important role in thermoregulation (maintaining normal body temperature). The avian respiratory system is different from that of other vertebrates, with birds having relatively small lungs plus nine air sacs that play an important role in respiration (but are not directly involved in the exchange of gases).

The air sacs permit a unidirectional flow of air through the lungs. Unidirectional flow means that air moving through bird lungs is largely 'fresh' air & has a higher oxygen content. In contrast, air flow is 'bidirectional' in mammals, moving back & forth into & out of the lungs. As a result, air coming into a mammal's lungs is mixed with 'old' air (air that has been in the lungs for a while) & this 'mixed air' has less oxygen. So, in bird lungs, more oxygen is available to diffuse into the blood."

http://arnica.csustan.edu/jones/Research/pdf/Res po nse%20to%20278.pdf

"We disagree for two reasons. First, we examined the comparative physiology literature and determined that maximum oxygen exchange rates of some extant reptiles overlap the oxygen consumption rates measured in some mammals during activity. Specifically, exceptionally active reptiles with multicameral lungs (for example, monitor lizards and sea turtles) have values of VO2 max that overlap or approach the oxygen exchange rates measured in similar size mammals during activity. Therefore, the septate lung in those reptiles must be capable of sustaining rates of gas flux characteristic of endotherms. However, mammals and birds "typically" have a greater VO2 max. Therefore, we addressed the question of what modifications in the oxygen transport system of an extant reptile would be necessary to support higher rates of oxygen consumption.

Inadequate preservation of the soft-tissue components of the oxygen transport system precludes accurate assessment of the aerobic potential of theropod dinosaurs. However, on the basis of metabolic patterns in extant reptiles and our theoretical analysis, we find that the notion that nonavian septate lungs constrain high oxygen flux rates is not supported. Our analysis suggests that modifications in lung structure were not a prerequisite for supporting higher oxygen consumption rates. In the mammalian and archosaur lineages that evolved endothermy, higher oxygen consumption rates could have been supported through changes in ventilatory mechanics and increases in blood oxygen content and cardiac output."

So it's not about the "cross-training" it's about how the lungs and blood works.

Those folks before the PT Extinction Event might simply have not been able to deal with the lower O2 levels and they all geeked it, while the habitable area decreased.

Re:16% oxygen?

[Wyatt Earp]

It compressed the inhabitable area on the surface while that and other things were happening that effected the oceans, and at the same time we have contiental shifts greating deserts and squeezing out the shallow seas.

It was a triple-witching hour for extictions.

Time of widespread regression of the seas.
Gymnosperms (seed plants) replaced many spore bearing plants.
Widespread accumulation of evaporites. More of Permian salt deposits than of any other age
Waters were hypersaline
Mass extinction at the end of the Permian
Trilobites all disappeared
Rugose and tabulate corals all disappeared
Blastoids all disappeared
Fusulinid forams all disappeared

3 Extinctions
Actually 2 or 3 events
End-Capitanian (Mid Permian)
End-Changsingian (LatePermian)
End-Olenekian (Triassic)

Re:Flow v. Floe

[Xilman]

Forgive me if this is off-topic, but does any geologist here know why we have volcanic flows whereas when we refer to icebergs we have floes. The reason for the spelling difference isn't immediately apparent in any of the dictionaries.

According to Chambers Dictionary, floe is probably from the Norwegian flo, meaning layer. The Old Norse is flO. The O character should really be a lower-case 'o' with an overbar, or a long-o, but that's not easy to represent here.

Flow is a noun in Scottish, meaning a morasse, a flat moist tract of land, a quicksand, a moorland pool, a sea basin or sound. This one is from a slightly different Old Norse root, though rather similar to the previous. The Old Norse is flOa, meaning to flood, with Icelandic flOi, a marshy moor, and Norwegian dialect floe, a pool in a swamp.

In Old English, the verb to flow, as appears in your example, was flOwan. I believe that the connection with this and the Scottish noun is through the Old Norse verb.

Paul

Re:Methane =/ CO2.

[GodsMadClown]

Green house efficiency is characterized by the magnitutude and bandwidth of absorption in the infrared spectrum. On a PPM to PPM concentration comparison, Methane is about 22 times more effective at trapping infrared radiation than CO2. That the infrared absorption characteristic is independant of its longevity in the atmosphere. Methane oxidises in the presence of O2 and has residence times measured in decades. CO2 uptake by plants and oceans is much slower, with residence times measured in centuries. Long-term sequestration in carbonate sediments happens on scales measured in millenia.

The wikipedia entry is likely more clear than me.

Re:Getting ridiculous

[ahunter]

Er, the parent post is so ignorant I don't even know where to begin.

Let's see...

1. Relevance to 'modern' global warming: none. This is a hypothesis to explain one of the biggest extinctions in the history of the planet. Whatever caused it, afterwards the planet was almost a complete desert.

2. The siberian volcano wasn't merely 'big'. It was the size of Europe! One of the biggest volcanoes to happen since life evolved on Earth. And it lasted a very long time: erupting pretty much constantly for a million years. Krakatoa wasn't even a damp fart in comparison, and it changed the climate for years. It's called a flood basalt eruption, and they are really rare.

3. We know something happened to the oxygen levels at that time. They've never recovered: before the extinction, oxygen levels were nearly double what we have now. Afterwards, oxygen levels were as low as they are now at the top of high mountains. Modern animals, including us, would have serious problems in that environment. Imagine what problems animals used to even more oxygen would have. Yep, they'd die.

4. The dinosaurs. Yes. Well. Guess which event preceded the dinosaurs? You don't suppose, perchance, that the reason the world was warmer when the dinosaurs were about was because of this? I mean, saying the dinosaurs were happy in a hotter climate, so it doesn't matter if it's hot is just dumb. The hot climate that the dinos lived in was what killed the creatures that came before. That made space for dinosaurs to appear.

Or to put it another way. Polar bears are perfectly happy when the temperature is -20 or lower. So naturally, everything else would be happy if the entire world was at this temperature. Yeah, right. (And of course, polar bears would be just fine living at the equator. The dinosaurs had it hotter! SHEEEESH)

5. The main cause of the fall in oxygen levels was supposedly a massive drop in sea levels. The most likely cause of this is supposedly global cooling caused by the volcanoes ash (there are very large carbon deposits under the sea, which would have become liberated when the sea levels dropped enough). This is what caused the global warming.

Finally, this is not sensationalistic. This huge extinction HAPPENED. The siberian volcano also happened, at the same time. The reduction in oxygen levels happened, too. A lot of other stuff happened at this time. There's very good evidence for all of this. The question the paper is trying to answer is what caused the extinction. This has bugger-all to do with global warming in a modern context, cows or even vogons.

This [bris.ac.uk] link describes the vulcanism in Siberia a bit better than the rather lame Yahoo article linked by the blurb.