Showing posts with label pleistocene. Show all posts
Showing posts with label pleistocene. Show all posts

Monday, September 28, 2009

Quaternary Revised


It has been decided to commence the quaternary at 2.6 million years before present in order to coincide with the beginning of the ice age and thus provide some significance.



Of course, this immediately asks a few questions but then previous lines did the same. I am most interested in establishing an association with the onset of the ice age and the closing of the Atlantic at the Equator if one properly exists.



I also think ice caps existed provided land was in place at the poles. It should now be possible to map land location somewhat, leaving room for crustal adjustments if any occurred. Land that straddled the poles deep in time should then show signs of such ice caps.



One thing though is of interest. Both the Antarctic cap and the Northern cap were intact for a very long time. The sea level was much lower as a result. I would like to determine it this effected the edge of the continental shelf in any way. It should not have, yet there is a coincidence there that is at least tantalizing



I think that we know enough to speculate on these matters safely and it may turn out that we can do a goods job of piecing together a proper history of polar and mountain glaciations. We know volcanoes hit heights of 10,000 feet. We also know that outside of the compression zones of the Andes and parts of the Alaskan Arc and the Himalayas and environs that other forms do not get much higher.



It is plausible that normal mountain building does not get much beyond 10,000 feet, and there is certainly plenty of that once you accept lower elevations.



Date of Earth's Quaternary age revised



by Staff Writers



London (UPI) Sep 23, 2009



http://www.terradaily.com/reports/Date_of_Earths_Quaternary_age_revised_999.html




The International Commission on Stratigraphy says it has revised the date of the start of Earth's prehistoric Quaternary Period by 800,000 years.


The London-headquartered commission -- the authority for geological science -- decided to end decades of controversy by formally declaring when the Quaternary Period started. The Quaternary age covers both the ice age and moment early man first started to use tools.


Researchers said Earth's history during the 18th Century was split into four epochs, Primary, Secondary, Tertiary and Quaternary. Although the first two have been renamed Paleozoic and Mesozoic, in that order, the second two have remained in use for more than 150 years.


"It has long been agreed that the boundary of the Quaternary Period should be placed at the first sign of global climate cooling," said University of Cambridge Professor Philip Gibbard, a commission member. "What we have achieved is the definition of the boundary of the Quaternary to an internationally recognized and fixed point that represents a natural event, the beginning of the ice ages on a global scale."


In 1983 the boundary was fixed at 1.8 million years, a decision which sparked argument since that point had no particular geological significance.


"For practical reasons such boundaries should ideally be made as easy as possible to identify all around the world. The new boundary of 2.6 million years is just that," Gibbard said.


The decision is detailed in the Journal of Quaternary Science.

Friday, August 21, 2009

Ancient Diets

When I read this, I am impressed by the fact that the Neanderthals were exploiting the game herds. This is important because it helps clarify their ecological brittleness and disappearance. They were a part of the ice age fauna in which a premium was placed on robustness. All their contemporaries went to the wall.

Certainly the Pleistocene catastrophe caused mass slaughter, yet I am reluctant to allow that as a complete answer. Part of it is because we have scant evidence of Neanderthals after 40,000 years ago leaving twenty thousands of years in which they should still have prospered. The other reason is that the advent of the Holocene ended their particular niche. The herds lost their niche and disappeared naturally themselves.

Mass slaughter certainly is devastating, but hold on a minute. If the niche is viable, repopulation is very swift. Let me put this in perspective. A dire disease eliminates the whole population of the old world but spares the Americas. It remains resource rich and we send in a million families to create scattered villages throughout.

We support fertility of one child every two years and thus one million settlers becomes five million inside a twenty year span. The next generation produces twenty five million. The one after that makes it 125 million, After that it is 625 millions and then 3,125 millions or effective restoration of population in a mere century or so by this simplistic thought experiment. The point though is that the biological capacity among humanity is there. Every other creature is faster still if the resources are readily available. Maybe not mammoths though :)

The bottom line is that elimination of the large game herds eliminated the large carnivores like the cave bear, mega lion and the ice age wolfs.

One proposition is that outside the ice age hunting niche, humanity wiped out the herds themselves who were vulnerable to human predation in particular. I tend to buy that. In North America, once the Indians had horses, the buffalo were doomed. They were easy to follow and hunt out. That would have taken an extra century or two without the encouragement of the hide market but it still would have happened and certainly happened to the bison in the old world.

In the old world, the advent of the horse on the northern plains eliminated all significant herd animals and replaced them with new managed herds. In most cases these were the horses themselves.

So what was so unusual during the Ice Age? It is accepted that most large animals simply became extinct twelve thousands of years ago and perhaps we can accept that as sufficient. It is just as important that their preferred niche was no longer supporting them and necessary to prevent any recovery.

I will make the odd conjecture that Neanderthal bands functioned right up to the Pleistocene Nonconformity. Their population was sparse and they followed the herds rotating in front of the ice. We merely have no evidence that this is true.

They had retreated from much of Europe because human predation of the herds had destroyed their life way there and they simply followed the ice were human hunting pressure was naturally lower. And as this item makes clear, humanity depended far more on skill based hunting and fishing that collected a far wider range of game.



http://www.newscientist.com/article/dn17595-seafood-gave-us-the-edge-...

12 August 2009 by Ewen Callaway

If Neanderthals ever shared a Thanksgiving feast with Homo sapiens, the two species may have had trouble settling on a menu.

Chemical signatures locked into bone suggest the Neanderthals got the bulk of their protein from large game, such as mammoths, bison and reindeer. The anatomically modern humans that were living alongside them had more diverse tastes. As well as big game, they also had a liking for smaller mammals, fish and seafood.

"It seems modern humans had a much broader diet, in terms of using fish or aquatic birds, which Neanderthals didn't seem to do," says Michael Richards, a biological anthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and the University of British Columbia in Canada.

Prehistoric menu

Such dietary differences could have played a role in the extinction of Neanderthals roughly 24,000 years ago.

"I personally think [Neanderthals] were out-competed by modern humans," says Richards. "Modern humans moved in with different, more advanced technology and the ability to consume a wider variety of foods, and just replaced them."

He and colleague Erik Trinkaus at Washington University in St Louis, Missouri, compiled chemical measurements taken from bone collagen protein belonging to 13 Neanderthals and 13 modern humans, all recovered in Europe. They also added data collected from a 40,000-year- old human recovered in Romania's Oase cave.

Because our bones are constantly destroyed and rebuilt while we are alive, the atoms that make up collagen hold a record of what we've eaten. "When you take a sample of a bone you're getting all those breakfasts, lunches and dinners for 20 years," Richards says.

Telltale atoms

Measurements of the abundance of heavy isotopes of carbon and nitrogen hold the key. Marine environments contain a higher proportion of heavy carbon atoms (carbon-13) than land ecosystems, so lots of carbon-13 in the recovered collagen points to a seafood diet. Meanwhile, heavy nitrogen (nitrogen-15) tends to build up as the atom moves up the food chain, from plants to herbivores to carnivores.

High levels of heavy nitrogen can also come from a diet with lots of freshwater fish. Aquatic food webs tend to contain more steps than terrestrial ecosystems, so large fish often have higher levels of heavy nitrogen than land predators.

By comparing the relative levels of these isotopes with those of animals found nearby, researchers can sketch the broad outlines of an ancient diet, if not every last calorie.

Carbon and nitrogen isotopes suggest that Neanderthals living between 37,000 and 120,000 years ago in what are now France, Germany, Belgium and Croatia got the bulk of their protein from large land herbivores, Richards and Trinkaus conclude. Levels of heavy nitrogen in Neanderthal bones invariably exceed levels in surrounding herbivores, and tend to match levels in that period's carnivores, such as hyenas.

Some modern humans living between 27,000 and 40,000 years ago opted for more varied diets. High levels of carbon-13 in two samples from Italy and France are evidence for a diet that probably included some marine fish or seafood.

Even other modern humans from a similar period that lived further inland seem to have enjoyed a more diverse menu. Unusually high levels of nitrogen-15 in their bones point to freshwater fish as an important source of food, Richards says.

Variety pays off

Such flexibility may explain why modern humans thrived in ancient Europe while Neanderthals perished, says Hervé Bocherens, a biological anthropologist at the University of Tübingen in Germany. "If modern humans were hunting big game, like Neanderthals, they would compete with them and deplete the resources."

When big game were scarce, modern humans could have survived and even flourished by eating fish and smaller animals. Neanderthal populations, by contrast, probably shrank and eventually disappeared in areas from which their more limited meal options disappeared.

However, Bocherens cautions against drawing too many conclusions from 13 Neanderthal skeletons, all unearthed in northern Europe. Collagen doesn't survive well in warmer climates, so researchers know less about the diet of Neanderthals in southern Europe and the Middle East, he says.

"There is evidence from a number of southern European sites in Portugal, Gibraltar, Spain and Italy that Neanderthals did exploit marine resources at times and, I would say, probably to a significant extent," says Chris Stringer, a palaeoanthropologist at the Natural History Museum in London. His team recently found cut marks on seal and dolphin bones in a Neanderthal cave in Gibraltar.

Palatable veg

Isotopes recovered from bone also ignore important sources of food that don't contain much protein. "I'm sure they're having vegetables," says Richards. "But they're not eating enough that it's being measured."

A new study of ancient DNA offers preliminary support for that conclusion. Neanderthals possessed a gene mutation that would have meant they couldn't taste bitter chemicals found in many plants.

There has been speculation that this mutation, which occurs in a taste receptor gene called TAS2R38, is beneficial to humans because it makes vitamin-packed vegetables more palatable. It probably arose in the common ancestor of modern humans and Neanderthals more than a million years ago. The gene encodes a receptor that detects a chemical called phenylthiocarbamide, which is closely related to compounds produced by broccoli, cabbage and Brussels sprouts.

If vegetables weren't part of the Neanderthal diet, the species would probably have lost the non-tasting mutation, says Carles Lalueza-Fox, a geneticist at the Institute of Biological Evolution in Barcelona, Spain, whose team sequenced TAS2R38 in 39,000-year-old DNA from a Neanderthal femur recovered in the El Sidrón cave in north-west Spain.

This Neanderthal's DNA tested positive for tasting and non-tasting versions of TAS2R38, suggesting he or she boasted copies of both alleles of the gene – and with it the ability to taste bitter foods. The presence of the non-tasting allele in this individual suggests it may have been beneficial to some Neanderthals.

"It doesn't mean they were eating Brussels sprouts or cabbage but it could be similar vegetables," Lalueza-Fox says.

Journal references: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0903821106

Biology Letters, DOI: 10.1098/rsbl.2009.0532

Thursday, July 3, 2008

Tunguska Implications

This was published in Nature by Duncan Steel to commemorate the Tunguska event centenary. It particularly describes the various attempts made to explain the event over the past century.

The fact not mentioned too loudly is that the vast majority of meteorites are stony and clearly capable of the same behavior. The incoming trajectory is likely comparable to a comet like orbital coming from the sun and arriving at speed.

What is important today is that we now know that a rapidly arriving large stony mass will be pulverized as it passes through the atmosphere leading to a massive explosion and heat release. Even without a visible touchdown we have seismic activity.

The big event associated with the Pleistocene nonconformity was vastly larger but that does not mean that the events of Tunguska were not mirrored. It is now clear that the heat front burned of all of North America causing the collapse of the mega fauna. The shock wave damaged the whole northern hemisphere even where heat was not a problem.

The existence of apparent impact craters in the Carolinas without debris in evidence conforms to air bursts along the entry path. The reaction of supersonic shock waves and air bursts with the surface is as yet not understood. We are seeing some rather broad hints.

I have already pointed out that the location of the disturbance was well situated to release the crust allowing it to settle into today’s configuration. This all requires vastly less kinetic energy than I had previously anticipated and described. Why use a hammer when it appears a tap will do? It was still the mother of all meteoric events during human history.

I had not anticipated a properly timed meteor strike with a flight path rather well aimed to achieve maximum effect. That was calling for a remarkable coincidence without any evidence.

Those readers who have not read my article on the Pleistocene Nonconformity are advised to do so since we tackle the key issue of crustal stickiness there.

It is clear that the risk of meteor striking the earth and causing massive damage is currently underestimated. Piecing together the Tunguska mystery has clarified many likely events in our past.

This also underlines the need for a global meteorite defense net and the existence of kinetic high orbit missiles able to intercept and disturb a meteor’s path. It need not be overbuilt in order to do its job. It just needs to be available for a one off need every century or so. Our hardware is likely up to the scanning job even now.

The statistical risk is very low but is not zero. The risk that such an event could destroy centers of humanity is also very low but not zero. Integrating a simple defense measure with our ongoing research efforts is a simple method of reducing even those odds. And as we progress in space exploration and exploitation the odds become even longer.

Today our culture is global, thus making a Tunguska like event survivable. Little comfort for the casualties, though.

Duncan Steel // Published online 25 June 2008 | Nature 453, 1157-1159 (2008)

PLANETARY SCIENCE: TUNGUSKA AT 100

"Sooner or later, it was bound to happen. On June 30, 1908, Moscow escaped destruction by three hours and four thousand kilometers - a margin invisibly small by the standards of the universe."

So begins Rendezvous with Rama , a 1972 novel by Arthur C. Clarke in which mankind learns the hard way about the dangers posed by incoming asteroids. The 2077 impact in northern Italy that Clarke goes on to describe is fictional: the 1908 blast was real. The early morning of 30 June 1908 saw, in an area around the Stony Tunguska river, the most explosive cosmic impact in recent history, hundreds of times more powerful than the atomic weapons set off over Hiroshima and Nagasaki. And yet, in part because it happened so far from civilization, and in part because it left no crater, it has not always been recognized as such. For decades it existed in a strange realm between science and pseudoscience, blamed on antimatter, black holes and alien spacecraft as easily as on a very fast bit of interplanetary refuse, and developing a mystique that has seen it associated with everything from energy drinks and rock bands to military missiles and The X-Files .

The approximate site of the blast's epicentre is now marked by a totem pole that researchers have dedicated to Agdy, the god of thunder in local mythology. Getting there is quite a trek, but the fascination of the site still draws an intermittent stream of scientists to the remote wilderness about 1000 kilometres north of Lake Baikal; they leave offerings at the totem pole to commemorate the trek. In the years directly after the blast, though, no one came at all. The first researchers did not arrive until the 1920s.

That does not mean there was no significant contemporary evidence to bring to bear. Siberia was and is an empty place - but a blast which, had it happened over Chicago, would have been heard from Georgia to the Dakotas, still drew a lot of attention. In the days following the blast, A.V. Voznesenskij, the director of the Irkutsk magnetic and meteorological observatory near Lake Baikal, began collecting accounts that are vivid with detail. There are people being knocked off their feet, a man needing to hold onto his plough to avoid being swept away by a powerful wind, the feeling of great heat "as if my shirt had caught fire", herds of hundreds of reindeer being killed, trees set alight by the radiance of the fireball only for the flames to be snuffed out by the subsequent blast wave. And the reports are unequivocal on the source of the blast. G.K. Kulesh, head of a meteorological station at Kurensk, 200 kilometres from the epicentre, told Voznesenskij that: "A meteorite of very enormous dimensions had fallen." (G.K. Kulesh: "There appeared in the northwest a fiery column Š in the form of a spear. When the column disappeared, there were heard five strong, abrupt bangs, like from a cannon, following quickly and distinctly one after another Š there had been a strong shaking of the ground, such that the window glass was broken in the houses Š It is probably established that a meteorite of very enormous dimensions had fallen.")

In the days after the blast, much of Europe experienced eerie 'bright nights': readers wrote to The Times in London, remarking that its columns could be read outdoors at midnight. Polarization measurements are consistent with this being due to sunlight scattered by dust in the very high atmosphere; observatories recorded increased atmospheric opacity and scattering across the Northern Hemisphere. This spreading dust may have been due to a plume ejected backwards along the incoming object's path by its explosion. Such plumes were seen on Jupiter when the fragments of Comet Shoemaker-Levy 9 slammed into it in 1994; hydrodynamic modelling by Mark Boslough and his colleagues at Sandia National Laboratories in Albuquerque, New Mexico, indicates that a similar terrestrial plume could be expected for an impact such as that at Tunguska.

There was, however, one good reason to doubt that a small asteroid was involved: the belief of the time that this would deliver a valuable hunk of iron to the surface. The Russian meteorite hunter Leonid Kulik, who led the first expedition to the epicentre in the 1920s, obtained funding from the Soviet government on the basis that he would find a valuable ore body there. But when he reached his goal in 1927 he found no metal. Nor did he find the crater that an impact was expected to leave. (There are now claims that nearby Lake Cheko might be such a crater, but these are widely disputed.) There were clear signs of violence - trees knocked flat over a vast swath of land - but no big hole in the ground. What could have happened?

In 1930, US astrophysicist Harlow Shapley suggested that the lack of a crater was due to the nature of the impactor. If it had been a comet, and comets were light and fluffy, then it would have exploded at altitude. This idea persisted for decades: in 1982 some planetary scientists were willing to postulate the extraordinarily low density of 3 kilograms per cubic metre in order to explain Tunguska in terms of the blast from a disintegrating comet.

Other explanations were even more far fetched than candyfloss comets. Soviet science-fiction author Alexander Kazantsev realized, as Shapley had, that the best explanation involved an explosion at altitude, and suggested in 1946 that a nuclear-powered alien spaceship exploding just before landing might have been the culprit, an idea taken up eagerly and earnestly in the following decades.

A more scientifically promising possibility was naturally occurring antimatter, a suggestion made independently by various people at various times. In 1940, Vladimir Rojansky of Union College, Schenectady, NY, suggested that some meteors and comets might be made of antimatter - 'contraterrene' matter in the terms of the time - and that their odd behaviour might be detectable. (More than 30 years later Rojansky suggested that it would be worth checking if Comet Kohoutek was one of the antimatter ones.) In 1941, Lincoln LaPaz of OSU in Columbus published two articles in the magazine Popular Astronomy that argued that large terrestrial craters and the craterless Tunguska explosion were both due to antimatter meteors; he later wrote to the Soviet Academy of Sciences suggesting a search for anomalous isotopes at the site.

More than a decade later, Philip Wyatt, a graduate student at Florida State University in Tallahassee, and Boris Podolsky, author of a famous paper with Einstein exploring apparent paradoxes of quantum mechanics, went to a movie in which antimatter featured. Podolsky pointed Wyatt towards Rojansky's 1940 paper and suggested he look into the impacts idea. Wyatt - now the chief executive of the Wyatt Technology Corporation in Santa Barbara, California - says that he was "mostly interested in looking for residual radioactivity" and published some ideas on the subject in Nature. "Other explanations were even more far fetched than candyfloss comets."

This notion was expanded on by three eminent American scientists (including 1960 Nobel Prize winner Willard Libby and Clyde Cowan, co-discoverer of the neutrino) in 1965. Libby, the original developer of the carbon-14 dating technique, found support for the idea of an antimatter impact from what seemed to be an elevated carbon-14 level in tree rings around the world in 1909, suggesting that significant quantities of the isotope had been created by radiation given off when the antimatter annihilated itself on contact with the thicker layers of the atmosphere. Even at the time, though, there were good arguments against the idea: among other things, the first gamma-ray-detecting satellites were not seeing the tell-tale radiation from antimatter annihilation elsewhere in the nearby cosmos.

Even more extreme, in 1973 two University of Texas physicists suggested that the cause was a black hole passing through Earth. This was nothing if not fashionable: miniature black holes had just been postulated by Stephen Hawking as after-effects of the Big Bang. Again the explanation was incomplete and its implications - an exit on the other side of the planet, and a seismic signal lasting well after the initial impact - unobserved. Similar caveats apply to the intriguing hybrid idea, aired as recently as 1989, that the culprit was a deuterium-rich comet turned into a hydrogen bomb by the heat and pressure of its arrival in the atmosphere.

Another approach has been to suggest that, despite the straightforward implications of eyewitness accounts of a bright object zipping across the sky, the source of the blast was in fact beneath the surface. A recent example is a claim that it was due to a 10-million-tonne belch of methane that subsequently exploded high in the sky. Others see a geophysical source involving peculiar tectonic behaviour.

The fact that such ideas were entertained (and still are, in some circles) speaks both of a certain fascination with the fanciful and the abiding need to explain that confusing lack of a crater. The fact that, by the 1960s, various craters around the world had been accepted as meteorite strikes meant that the anomalous lack seemed all the more confusing. In 1993 that confusion was allayed, at least for most people, by Chris Chyba, Kevin Zahnle and Paul Thomas. With the help of computer simulations derived from nuclear weapons' tests they showed that a solid, stony object about 50 metres across - the most likely sort of thing in that size range to hit the Earth - would not be expected to reach the ground. There was no need to invoke weirdly low cometary densities - at the relevant speeds the shock wave generated within a solid body as it slams into the atmosphere would rip up an everyday rock just fine. Formations such as Meteor Crater in Arizona are left by tougher impactors made of metal; the shock waves don't get the better of them until they've reached the ground.

A similar explanation was arrived at by Jack Hills, working at Los Alamos National Laboratory in New Mexico with Patrick Goda, and both teams had been to some extent pre-empted by a Soviet team led by V.P. Korobeinikov, the work of which had not been widely appreciated in the West. These various models led to an estimate that the blast was equivalent to about 15 megatonnes of high explosive - bigger than all but the very largest thermonuclear weapons. However, work by Boslough indicates that the energy required to fit the observed phenomena could be rather less, around 3 to 5 megatonnes.

That analysis assumes that the impactor was a stony asteroid - but a comet is still a possibility. In 1978, L'ubor Kresák suggested the Tunguska impactor was a fragment of Comet Encke. The peak of an annual intense meteor shower associated with dust from Encke occurred around 30 June 1908, but because the meteors arrived from the direction of the Sun, the shower would not have been visible to the naked eye. What the eyewitnesses said about the direction of the Tunguska projectile is consistent with that idea. An analysis of many hundreds of possible pre-impact orbits for the object published in 2001, by a team that had been led by the late Paolo Farinella, indicated that an asteroidal orbit was more likely than a cometary orbit - but using that paper's definitions, Comet Encke, which takes just 40 months to orbit the Sun, has an asteroidal orbit. Another line of evidence, suggested in 1977, was that a comet might explain the carbon-14 signature reported by Cowan in the 1960s; a comet in space might naturally be thoroughly irradiated.

The question of what the object was is not purely academic. If Tunguska was indeed a 15-megaton event, it was rather unlikely - such things are expected only every 1,500 years or so. That calculation, though, assumes that the flux of near-Earth objects is constant over time. If the population of near-Earth objects is replenished from time to time by the break-up of a comet, then shortly after that break-up, impacts from Tunguska-sized fragments will be more likely. Earth may suffer near misses from Tunguska's dark and stealthy cousins every time it passes through Encke's dust stream - fragments too small to be easily observed, but big enough to cause quite a mess if they hit.

In Rendezvous with Rama, Clarke's solution to the threat of impacts was an asteroid search programme aimed at ensuring that such a catastrophe could never occur again: he called it Project Spaceguard. This became the name of a real-life programme, and that search continues. But 50-metre objects are too small to spot far in advance of their impact. So although another Tunguska coming out of the blue is not a likely event in any given June, it is not out of the question.

Duncan Steel is an astronomer and writer after whom Arthur C. Clarke once named a robot.

-- +++

NEO News (now in its fourteenth year of distribution) is an informal compilation of news and opinion dealing with Near Earth Objects (NEOs) and their impacts. These opinions are the responsibility of the individual authors and do not represent the positions of NASA, Ames Research Center, the International Astronomical Union, or any other organization. To subscribe (or unsubscribe) contact dmorrison@arc.nasa.gov. For additional information, please see the website http://impact.arc.nasa.gov. If anyone wishes to copy or redistribute original material from these notes, fully or in part, please include this disclaimer.

Monday, January 28, 2008

The Real Great Flood

The one aspect of the onset of the Holocene that I find difficult to understand is the fact that so little is made of it.

Before the break, mankind was restricted to operating in a very narrow tropical band on a small fraction of the globe's land surface. Every where else the climate marched back and forth very quickly over several degrees making agriculture totally impossible with the possible exception of some herding. And the carnivores made that pretty dicey.

Today, that same temperature swing is a half degree or so every century, and we still yell.

When the ice age ended 12,500 years ago, the northern ice melted raising the sea level 300 feet over a number of centuries. This sank the edge of the continental shelf below sea level everywhere, inundating coastal plains everywhere.

This certainly explains the Bronze age traditions of a great flood that humanity fled. The rest of the story means little in the face of the universality of this coastal inundation that destroyed most of the human habitat of the time.

My own small contribution is to attempt to understand the crustal shift mechanism that brought these changes into been. In any event, the actual collapse of the ice age is a historic reality, regardless of causation. At least my causation mechanism has the benefit of promising us a continuation of the Holocene (or Antropocene) for millions of years. Does anyone understand just how incredibly lucky we are to have the current crustal configuration that we have?

The Arctic is a nearly closed sea that could easily become an icecap again if any number of significant shifts took place . How did we end up with the right configuration in the first place? It has been suggested that the crust shifted several times in order to get it right. I find this difficult to subscribe to because it seems so unnecessary. Once by accident seems good enough. However, if the dynamic causation model in fact predominates, then multiple shifts become natural until the exact configuration emerges that eliminate the northern ice cap.

I also note that the southern ice cap is stable on a large land mass, but is tightly bounded ensuring any excess ice finds its way into the ocean long before there is enough build up to endanger global crustal balance.

I suspect that this configuration is stable until plate tectonics finally changes the configuration, millions of years from now.

This still begs the question of why are we not making more of the dramatic change that occurred a mere 12500 years age. It undoubtedly made it possible for the human animal to populate the globe as an agriculturalist. And it seems strange that the promoters of biblical studies do not jump on this, although it queers any more recent middle eastern scenario. However, they usually have no difficulty in questioning the age of anything.

My publication of the Pleistocene Nonconformity a few months back covers the causation problem in some detail for the interested reader. It can be found on the View Zone.

Friday, November 16, 2007

The Global Climate Engine

I have just commenced reading a book that focuses on the past 20,000 years of human development as seen through the eyes of archeology. It appears useful and once I have properly gotten into it I will do a review for you all. What really jumped out at me however, was a chart that maps the oxygen isotope ratio in the ice caps.

Variations in the ratio is a proxy for whether the global climate is warmer or colder. It is also reasonably reliable over the twenty thousand year time span as is the ability to take ice samples in the Antarctic covering the same period. I think that we can accept the results as useful over the designated time span. What certainly can be trusted is the observed variability ratio.

What stands out in the chart is that the Pleistocene Nonconformity is more abrupt than perhaps understood before. The global climatic shift was not just from a seriously cooler climate to the our warmer era known as the Holocene, but from a clearly very volatile regime of shifting worldwide climatic conditions to the current regime of very low variability.

The chart is utterly compelling. For twelve thousand years the chart has flat lined showing minimal variability. Prior to that, not only was the average temperature colder, it moved back and forth over a wide range of variability that is at least an order of magnitude greater than is apparent today.

In reality, this confirms the geologic nature of the Pleistocene Nonconformity more that any other argument. A one million year regime that included a huge northern icecap ended in a couple of thousand years due to the ice cap been shifted thirty degrees into a nonsustaining environment that also was able to prevent the mere rebuilding of the icecap in one place as it was been melted in another. We had an incredibly lucky throw of the dice that has actually likely seen the global climate restored closer to the type of climate experienced over the past billion years.

My readers will want to revisit my posts under Pleistocene Nonconformity back in June and July.

For the record, the onset of the northern ice age coincides with the establishment of the Panama - Central American land bridge that closed off the Atlantic a million years ago. A pretty unique event in global geologic history. It has also taken a pretty unique configuration to prevent the establishment of a full icecap at the pole during our era. It is principally dependent on a large imbalance of northern equatorial waters been forced into the Arctic. It is almost an engine.

That engine has made the northern hemisphere hugely habitable to ourselves. Without it, North America, Europe and all of temperate Asia becomes largely uninhabitable, as was true during all of the Pleistocene.

Perhaps now we understand better why humanity broke out of the tropics only ten thousand years ago. Prior to that it was not really a very good option. All the advantages of the temperate climate were simply not available and in those small areas were they existed, wide climate swings made any culture other than game hunting terribly vulnerable. Our so called climate shifts are trivial by comparison.

Thus, prior to the shift from Pleistocene to Holocene, mankind could hope to establish a proto civilization in only the tropics and semi tropics. This included all of Africa, the Indonesian Plain and India and not much else.

The advent of the Holocene gave us the world and the possibility of agriculture as we know it.

Tuesday, July 31, 2007

Pleistocene Nonconformity - 6 - the changes

What makes the logic of this shift so compelling to myself is the elimination of a lot of theoretical impossibilities that the scientific community was forced to accept simply because they were there. We replaced Noah's ark as an explanation for an Ice age location or two that was simply impossible by climatic ideas of the past and I am rather certain, doubly impossible with today's climatic knowledge.


Resultant Crustal Changes

1 Hudson Bay, formerly the pole is shifted south by thirty degrees, taking the bulk of the massive north American Polar Ice sheet into temperate climes. This is extraordinarily important because it ultimately releases this ice into the ocean lifting sea levels over 150 feet. The Laurentian sheet finished melting out about 9,000 years ago, 3,000 years after the Scandinavian Sheet and the European Mountain glaciers which also contributed 150 feet in sea level gain.

2 Greenland migrates from one side of the polar region to its current locale staying within the Arctic Circle and permitting the survival to date of its ice cap. Precipitation levels change. This conforms to the anomalous precipitation levels currently experienced in both Greenland and Antarctica. Less precipitation is now associated with the thickest ice sheets and vice versa for both regions.

3 The Caribbean shifts from the Temperate Zone to the tropics commencing the full heat pump of the Gulf Stream. This leads directly to the warming of Europe and the swift removal of the Scandinavian Ice Sheet and the first major lift of the sea level. Between the two ice sheets enough fresh water was supplied for the sea level to rise 300 feet. Prior to the application of this heat pump the two sheets likely covered the entirety of the Arctic Sea and partially inland at all the margins. The only release was ice calving in the North Atlantic at the edge of the Arctic shelf and through the Davis Strait. There is no reason to assume that much of it was even floating since huge thicknesses existed. The Northern Hemisphere was much like Antarctica today with massive seaborne ice sheets struggling to reach open water.

4 Eastern Siberia migrates from cold Temperate Zone conditions to the sub Arctic. Conditions do not markedly change as we move from a world of extensive glaciation as existed in Europe to one further north and just as unpleasant. The major change comes over time as the grounded Arctic Ocean ice sheet dissipates and fresh water accumulations from the northern Siberian plains escape into the sea. Little is thoroughly understood, but it is likely that much Siberian Drainage had no escape route except to ultimately build ice on the Arctic Sheet. This may also hold for the Mackenzie River in Northern Canada.

5 Africa merely rotates around the center of rotation in the Congo. With the exception of a wave of earthquakes and tsunamis, life goes on virtually unscathed with minor climate changes. Africa retained massive genetic diversity, while the rest of the global population was almost wiped out, probably reduced to remnant hunter-gatherers in the hills with the necessary survival skills. Genetic diversity collapsed. It is also argued that since Africa is the homeland of all primate development, this diversity is it’s expected due. This might be true except there is no wall and movement and forced intermarriage is the norm for these populations. Because of the huge time frames involved, I am more inclined to expect close similarity in terms of genetic complexity in the Old World. Certainly any successful base population could cover the geography of the Old World in an historical eye blink.

In fact many of the putative successor populations in the Old World outside of Africa appear to be strongly linked to the mountainous regions of Central Asia. These were never areas famous for naturally promoting high population densities. Their genetic influence can only be possible if the much denser natural populations of the lowlands had disappeared.

6 Europe is tilted slightly northward, but the advent of a hugely strengthened Gulf Stream is now the major factor in climate change. The Mediterranean begins to warm up as the northern glaciers swiftly disappear inducing the first major lift in sea levels. The Scandinavian ice sheet and the extensive mountain glaciations are eliminated as well as near sub arctic to Arctic conditions.

7 The Amazon shifts from been largely north of the equator to been largely south of the equator. It remains in the tropics and experiences little change save coastal devastation.

8 India and Southeast Asia including southern China and most of Indonesia shift from the south tropical zone to the north tropical zone. Climatic conditions remain largely the same although a major redistribution of rainfall probably takes place. Inundation from the sea is at its worst here, simply because of the area’s total vulnerability to the likely maximum stroke of the tsunamis. There is no shelter from any direction except into the Himalayas. This area was on the arc of rotation.

9 Australia was deep into the temperate to sub arctic. It moved north into the warm temperate to sub tropical. Glacial cover as existed was removed, particularly in Tasmania.

10 The bulk of Antarctica stayed within the Antarctic Circle preserving the main ice cap. The remainder (Lesser Antarctica) which was sub arctic to almost temperate moved into the Antarctic Circle and started rapidly accumulating additional ice. A warm ocean current similar to the Gulf Stream may have originally bathed this area, leaving a lot of room for climate variation and habitability. Otherwise, it would certainly have been highly glaciated and cold prior to the crustal shift.

Let us take this a little further. We have already intimated that polar ice caps are just that. Global rotation forces atmospheric circulation in such a way as to create a profoundly stable accumulation environment at the poles. Antarctica is an excellent example. What went wrong in the Arctic? Millions of years of ice accumulation disappeared in a geological second. A huge part of the answer, at least for Europe, was the emergence of the Gulf Stream, which delivered the heat necessary to not only eliminate the Scandinavian icesheet, but also prevented the Arctic Ocean and the islands west of Greenland from been covered with ice as they should be.

Even if we do not accept the premise of a global shift of the crust we still have to explain where the heat build-up in the Atlantic tropics went for the preceding millions of years. This leaves only the South Atlantic and the Antarctic Archipelago, which is rotationally in the right direction. Pre shift we would still have a weak Gulf Stream that delivered plenty of moisture but far less heat, and a strong southern current that pumped heat and moisture into a temperate Lesser Antarctica.

11 The Pacific rotated like Africa on an axis near its center. Ferocious Tsunamis on its edges would have been restrained by the massive mountain ranges girding it with the exception of the area of Southeast Asia.

The most compelling argument for the validity of this event is the simple fact that it eliminates an even more troublesome theory. That the output of the sun declined so substantially as to expand subarctic and arctic conditions deep into the Temperate Zone. We do not have permanent ice on Baffin Island or Bathurst inlet or in Siberia today, yet the climate there is at the limit of our capability for sustaining a presence. And the Sun’s annually available energy there, is a fraction of what is received in Buffalo. For an ice sheet to develop and be sustained in the latitudes of Buffalo, the sun’s energy output would have to drop to much less than currently received today in the high arctic.

Other consequences of such low solar output would be the elimination of larger life forms in the sub Arctic at least. This includes Siberia. The tropics would see snow and killer frosts similar to current temperate conditions along with massive mountain glaciation, sharply reducing plant diversity. All the available evidence supports none of this. At the most an Antarctic style ice sheet chilled the Northern Temperate zone and generated a somewhat cooler sub tropical zone. This may have been more local than general.

The likely truth supported by our knowledge of stellar physics is that the sun’s energy output has only fluctuated mildly during the last three billion years. And this ultimately means that polar icecaps had to be at the pole, not the latitude of Buffalo. Polar icecaps form at the pole and spread out from there for a lot of good reasons to do with atmospheric convection and maximum heat loss. They do not form elsewhere.

The one major consequence of this type of event is that the North Polar Region is now largely oceanic. It may be that when the next cyclical cold spell arrives in about 18,000 years, this region will not be able to buildup the ice sheet normally associated with an ice age and the Northern Hemisphere will be largely spared. It will still be chilly.

Although this is off topic, a rather interesting geological consequence of the mile thick polar Laurentian ice sheet was that the land itself was depressed by perhaps up to a thousand meters. This depressant effect extended into the Western Canadian Sedimentary basin.

Now when organic material sinks below two thousand meters, heat, water and pressure combine to convert this material into oil. When this oil is formed it then migrates upward to the surface unless trapped by sealed strata. In practice most of this oil escapes back into the surface environment leaving a scant remnant behind, which is the source of all our oil industry. During the million-year life of the polar ice sheet the eastern edge of the sedimentary basin was pushed down, sending a huge thickness of organic bearing strata into the oil production zone. As a result the produced oil came to the surface and was initially preserved by the extreme conditions associated with the high latitudes. These today form the Canadian Tar Sands, which today represents a possible twenty percent of the global oil reserve.

On an optimistic note, related subsurface heavy oil deposits in combination with the Tar Sands could approach one trillion barrels of producible reserves. This is as much as has been used globally over the past one hundred years. And the necessary production technique breakthroughs are happening now.