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-- Assyrian clay tablet points to 'Sodom and Gomorrah' asteroid - 3/31/08
-- Ice Ages Blamed on Tilted Earth - 3/30/05
-- Proof on Ice: Southern Greenland Was Once Green; Earth Warmer - 7/05/07
-- Arctic Ice Caps May Be More Prone to Melt - 06/22/12
-- Siberia was a wildlife refuge in the last ice age - 1/10/12 (20)
-- Russians revive Ice Age flower from frozen burrow - 2/21/12 (16)
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Record-Breaking Ice Core May Hold Key to Climate Variation - 04/10/04
 

 Assyrian clay tablet points to 'Sodom and Gomorrah' asteroid

31 Mar 2008 Lester Haines

29 June 3123 BC starts with a bang

A Cuneiform clay tablet which for over 150 years defied attempts at
interpretation has now been revealed to describe an asteroid impact which
in 3123 BC hit Köfels, Austria, leaving in its wake a trail of destruction which
may acccount for the biblical tale of Sodom and Gomorrah.

The Planisphere clay tablet. Pic: Bristol UniversityThe "Planisphere" tablet
(see pic) - inscribed around 700 BC - was unearthed by Henry Layard in the
remains of the library of the Assyrian royal palace at Nineveh, close to
modern-day Mosul, Iraq. It's a copy of the night diary of a Sumerian
astronomer containing drawings of constellations and "known constellation
names", but it required modern computer tech to finally unravel its exact
meaning.

Alan Bond, Managing Director of Reaction Engines Ltd and Mark Hempsell,
Senior Lecturer in Astronautics at Bristol University, subjected the
Planisphere to a programme which "can simulate trajectories and
reconstruct the night sky thousands of years ago". They discovered that it
described "events in the sky before dawn on the 29 June 3123 BC", with
half of it noting "planet positions and cloud cover, the same as any other
night".

The other half, however, records an object "large enough for its shape to
be noted even though it is still in space" and tracks its trajectory relative to
the stars, which "to an error better than one degree is consistent with an
impact at Köfels".

That a large body had impacted at Köfels had long been suspected, the
evidence being a giant landslide 500m thick and five kilometres in diameter.
The site had no impact crater to back the theory, but the researchers now
believe they have a plausible explanation for that.

The Bristol Uni press release explains: "The observation suggests the
asteroid is over a kilometre in diameter and the original orbit about the Sun
was an Aten type, a class of asteroid that orbit close to the earth, that is
resonant with the Earth’s orbit. This trajectory explains why there is no
crater at Köfels.

"The in coming angle was very low (six degrees) and means the asteroid
clipped a mountain called Gamskogel above the town of Längenfeld, 11
kilometres from Köfels, and this caused the asteroid to explode before it
reached its final impact point.

"As it travelled down the valley it became a fireball, around five kilometres in
diameter (the size of the landslide). When it hit Köfels it created enormous
pressures that pulverised the rock and caused the landslide but because it
was no longer a solid object it did not create a classic impact crater."

Mark Hempsell, hinting at the possible fate of Sodom and Gomorrah, adds:
“Another conclusion can be made from the trajectory. The back plume from
the explosion (the mushroom cloud) would be bent over the Mediterranean
Sea re-entering the atmosphere over the Levant, Sinai, and Northern Egypt.

“The ground heating though very short would be enough to ignite any
flammable material - including human hair and clothes. It is probable more
people died under the plume than in the Alps due to the impact blast.“

While the biblical fate of the legendary dens of vice (“Then the Lord rained
down burning sulfur on Sodom and Gomorrah - from the Lord out of the
heavens” - Genesis 19:24) sits nicely with the asteroid theory, it's never
been categorically proven that they actually existed in their suspected
location close to the Dead Sea.

Tales of fiery destruction raining from the skies are not, though, restricted
to the Bible. Hempsall told the Times that "at least 20 ancient myths record
devastation of the type and on the scale of the asteroid’s impact" -
including the Ancient Greek myth of how Phaeton, son of Helios, lost control
of his dad's chariot and plunged into the River Eridanus.

A translation of the Planisphere and the researchers' findings can be found
in the book A Sumerian Observation of the Köfels' Impact Event. The tablet
is object number K8538 in the British Museum collection.
 

 Ice Ages Blamed on Tilted Earth

by Michael Schirber    March 30, 2005     For LiveScience.com

In the past million years, the Earth experienced a major ice age about every 100,000 years. Scientists have several theories to explain this glacial cycle, but new research suggests the primary driving force is all in how the planet leans.

The Earth's rotation axis is not perpendicular to the plane in which it orbits the Sun. It's offset by 23.5 degrees. This tilt, or obliquity, explains why we have seasons and why places above the Arctic Circle have 24-hour darkness in winter and constant sunlight in the summer.

But the angle is not constant - it is currently decreasing from a maximum of 24 degrees towards a minimum of 22.5 degrees. This variation goes in a 40,000-year cycle.

Earth's Wobble is like the precession of a spinning top.

Peter Huybers of Woods Hole Oceanographic Institution and Carl Wunsch of the Massachusetts Institute of Technology have compared the timing of the tilt variations with that of the last seven ice ages. They found that the ends of those periods - called glacial terminations - corresponded to times of greatest tilt.

"The apparent reason for this is that the annual average sunlight in the higher latitudes is greater when the tilt is at maximum," Huybers told LiveScience in a telephone interview.

More sunlight seasonally hitting polar regions would help to melt the ice sheets. This tilt effect seems to explain why ice ages came more quickly - every 40,000 years, just like the tilt variations -- between two and one million years ago.

"Obliquity clearly was important at one point," Huybers said.

Colder planet

The researchers speculate that the glacier period has become longer in the last million years because the Earth has gotten slightly colder - the upshot being that every once in a while the planet misses a chance to thaw out.

The glacial cycles can be measured indirectly in the ratio of heavy to light oxygen in ocean sediments. Simply put, the more ice there is on Earth, the less light oxygen there is in the ocean. The oxygen ratio is recorded in the fossils of small organisms - called foraminifera, or forams for short - that make shells out of the available oxygen in the ocean.

"These 'bugs' have been around for a long time - living all across the ocean," Huybers said. "When they die, they fall to the seafloor and become part of the sediment."

Drilled out sediment cores from the seafloor show variations with depth in the ratio of heavy to light oxygen - an indication of changes in the amount of ice over time. This record of climate change goes back tens of millions of years.

By improving the dating of these sediments, Huybers and Wunsch have showed that rapid decreases in the oxygen ratio - corresponding to an abrupt melting of ice - occurred when the Earth had its largest tilt.

Other orbital oddities

The significance of this relationship calls into question other explanations for the frequency of ice ages.

One popular theory has been that the noncircular shape, or eccentricity, of Earth's orbit around the Sun could be driving the glacial cycle, since the variations in the eccentricity have a 100,000-year period. Curiously different, but interesting.

Variation in Orbit

A Tilt period is ever 40,000 years on average
A Wobble period is every 20,000 years on average
A Eccentricity period is every 100,000 years on average

By itself, though, the eccentricity is too small of an effect. According to Huybers, changes in the orbit shape cause less than a tenth of a percent difference in the amount of sunlight striking the planet.

But some scientists believe a larger effect could be generated if the eccentricity fluctuations are coupled with the precession, or wobble of the Earth's axis. It's like what is seen with a spinning top as it slows down.

Earth's axis is currently pointing at the North Star, Polaris, but it is always rotating around in a conical pattern. In about 10,000 years, it will point toward the star Vega, which will mean that winter in the Northern Hemisphere will begin in June instead of January. After 20,000 years, the axis will again point at Polaris.

Huybers said that the seasonal shift from the precession added to the eccentricity fluctuations could have an important effect on glacier melting, but he and Wunsch found that the combined model could not match the timing in the sediment data.

Skipping beats

The question, then, that Huybers and Wunsch had to answer: How does the 40,000-year tilt cycle make a 100,000-year glacial cycle? A more careful sediment dating has shown is that the time between ice ages may on average be 100,000 years, but the durations are sometimes 80,000 years, sometimes 120,000 years -- both numbers are divisible by 40,000. It appears there was not a mass melting every time the tilt reached its maximum.


Did You Know?

"The Earth is skipping obliquity beats," Huybers explained.

The planet only recently started missing melting opportunities. Although the researchers have no corroborating evidence, they hypothesize that the skipping is due to an overall cooling of the planet.

The last major glacial thaw was 10,000 years ago, which means that the Earth is scheduled to head into another ice age. Whether human influences could reverse this, Huybers was hesitant to speculate. Other researchers have found evidence that the process of climate warming can set up conditions that create a global chill.

"What we have here is a great laboratory for seeing how climate changes naturally," he said. "But this is a 100,000-year cycle, whereas global warming is happening a thousand times faster."

http://www.livescience.com/6937-ice-ages-blamed-tilted-earth.html
 


 Proof on Ice: Southern Greenland Was Once Green; Earth Warmer

Using ice cores from Antarctica and Greenland, researchers have extended the climate record back 800,000 years and have shown that the world's largest island may have been sealed in ice for at least that long

July 5, 2007     By David Biello     COURTESY OF DORTHE DAHL-JENSEN

In 1981 researchers removed a long tube of ice from the center of a glacier in southern Greenland at a site known as Dye 3. More than a mile (two kilometers) long, the deep end of the core sample had been crushed by the pressure of the ice above it and sullied by contact with rock and soil. By destroying the pattern of annual layers, this contamination seemingly made it impossible to assess the region's ancient climate. But DNA extracted from the previously ignored dirty bottom has revealed that Greenland was not only green, it boasted boreal forests like those found in Canada and Scandinavia today.

Biologist Eske Willerslev of the University of Copenhagen and an international team of colleagues discovered DNA from alder, spruce, pine and yew trees at the glacier's base as well as insects ranging from butterflies to spiders. This is the "first evidence for a forested southern Greenland," Willerslev says. And based on the tree species found, Greenland must have been warmer than 50 degrees Fahrenheit (10 degrees Celsius) in summer and never colder than one degree F (–17 degrees C) in winter, much warmer than present conditions.

Willerslev used four measures (traces of last exposure to sunlight in minerals, how long ago the amino acids were part of a living creature, the relative levels of beryllium and chlorine isotopes, and the "clocks" contained in the DNA) to date the forest to at least 400,000—and possibly as much as 800,000—years ago, the team reports in Science. That means this area of southern Greenland has been continuously coated in ice for at least that long.

The ice sheet on Greenland, therefore, is more stable than some scientists previously believed and "has not contributed to global sea level rise during the last interglacial," Willerslev says. "Importantly, it does not mean that we should not be worried about future global warming as the sea level rise of five to six meters during the last interglacial must have come from somewhere."

Glaciologist Richard Alley of Pennsylvania State University, who was not involved in the study, agrees: "Something else," possibly Antarctica, must have provided the water for global sea level rise "because this observation does not at all affect [that] estimate … only the estimate of where the water came from."

Adds team member and glaciologist Martin Sharp of the University of Alberta in Edmonton: "One could argue that this shows that natural forcing could account for the current warm conditions, but the current orbital configuration does not support this, even when other natural forcings are taken into account. One could also argue that if natural warming can deglaciate much of southern Greenland, then natural warming plus anthropogenic warming could cause even more extensive deglaciation."

Looking at an ice core from a site on the glaciated continent of Antarctica known as Dome C, scientists have stretched the climate record back 800,000 years, tracking eight successive glacial periods, according to another online report in Science. The data shows that natural variations in Earth's orbit—obliquity, or how tilted the planet is in relation to the sun—have determined global temperatures in the past, they report. "This helps us put current warming into context," Sharp notes, "but it really has nothing to say about the mechanisms driving the current warming."

Applying the DNA techniques developed by Willerslev and his colleagues to the silty bottoms of such an Antarctic core may reveal the ice-free history of that continent as well. "In Antarctica, where the ice cover is thin and thus the bedrock is very cold [about –58 degrees F (–50 degrees C)] I think you could go very far back in time," Willerslev says. "What to find? I have no idea." The past, it appears, is on ice and waiting.

http://www.scientificamerican.com/article/proof-on-ice-southern-greenland-green-earth-warmer/
 

 Arctic Ice Caps May Be More Prone to Melt
A new core pulled from Siberia reveals a 2.8-million-year history of warming and cooling
June 22, 2012 |By Lauren Morello and ClimateWire
|
Today, the Arctic is synonymous with "cold." But a new study suggests the polar region has experienced periods of intense warmth over the past 2.8 million years that may have been hot enough to melt the Greenland ice sheet.

Scientists already knew that the Arctic is warming twice as fast as the global average. But the new study, based on a sediment core drilled from a Russian lake, suggests the far north's climate is even more sensitive than researchers suspected.

"There are really big surprises in the history of the Arctic that are revealed in the cores," said Julie Brigham-Grette, a geologist who studies the climate of the past 3 million years.

She's a co-author of the study and was the lead American scientist on the international project to drill the sediment core at Lake El'gygytgyn in the northeastern Russian Arctic. Its results were published yesterday in the journal Science.

"We've identified almost a dozen intervals in the core over the last 2.8 million years when the climate was naturally much warmer than the present," Brigham-Grette said. "It gives us a very interesting clue about how sensitive the Arctic is to change."

Conditions were so toasty during two of the warm periods, between 400,000 and 1.1 million years ago, that scientists believe the Greenland ice sheet may have disappeared entirely.

The question now for researchers is why.

Increasing concentrations of greenhouse gases in the atmosphere have driven recent warming of the Earth's climate. And wobbles in the planet's rotation probably kick-started the end of the last ice age, about 19,000 years ago, by bringing Earth closer to the heat of the sun.

But what scientists know about ancient greenhouse gas levels and changes in Earth's rotation doesn't fully explain why the Arctic was so much warmer millions of years ago, at the farthest reaches of the period documented by the new lake core, according to climate modeling results included in the new study.

Previous research on carbon dioxide levels in the atmosphere, for example, suggests they were not as high then as they are today.

Causes of earlier warmth not clear
Brigham-Grette and her colleagues believe that the missing ingredient may be feedback loops that acted to intensify warming started by other factors, especially in the Arctic.

They are likely the same feedback processes scientists are seeing evidence of now and projecting for the near future, she said -- such as shrinking Arctic sea ice driven by rising temperatures.

As the Arctic's icy cap recedes, it enlarges the area covered by dark, open water that absorbs more heat than the white ice it replaces. That creates a circle that hastens the melting of the ice that remains.

There are other tantalizing clues buried in the Lake El'gygytgyn sediment core.

The scientists noticed that many of the dozen warm periods in the sediment record over the last 2.8 million years seem to have occurred when the West Antarctic ice sheet melted away, as documented in Antarctic sediment cores.

They speculate that the warm periods at the poles may be connected -- that those warm periods intensified first in Antarctica, melting the West Antarctic ice sheet.

That might have altered ocean circulation, warming surface water in the north Pacific Ocean and eventually temperatures throughout the Arctic.

Antarctic melt may have accelerated the Arctic's
Or the loss of West Antarctica's ice could have raised the sea level, pushing warm surface water through the Bering Strait into the Arctic Ocean and warming the region.

For researchers trying to understand the future climate, studying the distant past is important because it can reveal climate surprises -- forces that shaped the ancient climate that may crop up again.

"Geologists and people who do paleoclimate studies are kind of like Doctor Who," Brigham-Grette said, referring to the time-traveling British television character. "We can go backward and forward in time. We can look at how things play out."

But doing so isn't easy. Retrieving the sediment core from Lake El'gygytgyn required more than a decade of planning before drilling commenced in 2009.

The frozen Siberian lake, an impact crater formed by a meteor crash 3.6 million years ago, was an ideal drilling site for scientists because it was never covered by glaciers, which scrape the earth below as they flow and surge, scouring away layers of sediment and bedrock.

Scientists were able to retrieve a pristine record of the past 3.6 million years from the lake's bed, recreating a lost world by analyzing the chemistry of the sediments, examining the thickness of the layers and studying pollen and fossils trapped inside them.

That work is continuing. The researchers are preparing another analysis that will look even further into the past, examining the period from 2.2 million to 3.6 million years ago.

The research was funded by the International Continental Scientific Drilling Program, the National Science Foundation, the German Federal Ministry of Education and Research, the Alfred Wegener Institute, GeoForschungsZentrum-Potsdam, the Russian Academy of Sciences, the Russian Foundation for Basic Research and the Austrian Ministry of Science and Research.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500
 
 

 Siberia was a wildlife refuge in the last ice age

10 January 2012 by Wendy Zukerman New Scientist Magazine issue 2846

SIBERIA, a name that conjures up images of snow and ice, may have been an unlikely refuge from the bitter cold of the last ice age. Ancient DNA from the region paints a picture of remarkably stable animal and plant life in the teeth of plunging temperatures. The findings could help predict how ecosystems will adapt to future climate change.

The permanently frozen soil of Siberia, Canada and Alaska preserves the DNA of prehistoric plants, fungi and animals. "It's a giant molecular freezer," says James Haile at Murdoch University in Perth, Western Australia.

Glacial ice can also contain ancient DNA but permafrost is much more abundant than ice and so should provide a more complete picture of the effects of prehistoric climate change, says Haile. Last month, at the International Barcode of Life Conference in Adelaide, South Australia, his colleague Eva Bellemain of the University of Oslo in Norway revealed the first fruits of their analysis of Siberian permafrost DNA.

The samples were extracted from 15,000 to 25,000-year-old frozen sediment in southern Chukotka in north-eastern Siberia. Their age is significant: around 20,000 years ago temperatures plummeted and ice sheets blanketed much of the northern hemisphere - but parts of Siberia, Canada and Alaska apparently stayed ice-free (Quaternary Science Reviews, DOI: 10.1016/j.quascirev.2011.07.020).

Fossils and pollen found in these regions suggest they may have acted as a refuge for plants and animals during this time, but Bellemain turned to fungal DNA to get a complete picture of the environment. Many fungi consume plants, and so indicate the plant life around at the time.

Using 23 permafrost cores, Bellemain identified around 40 fungal taxa that thrived during the last ice age. "We didn't expect to find so much," she says.

The diversity of fungi found suggests that a brimming plant community thrived in northern Siberia to support them. This range of plants should also have sustained a diverse assembly of mammals - and the samples indeed contain DNA from woolly rhinoceros (Coelodonta antiquitatis), woolly mammoths (Mammuthus primigenius), reindeer (Rangifer tarandus) and moose (Alces alces) dating back to between 15,000 and 25,000 years ago (Molecular Ecology, DOI: 10.1111/j.1365-294x.2011.05306.x).

Meanwhile, Haile and Tina Jørgensen at the University of Copenhagen in Denmark have used ancient DNA together with pollen and fossil evidence to reconstruct the plant life surrounding Lake Taymyr, on the Taymyr peninsula in northern Siberia. Using 18 cores from five sites around the lake, the team identified 66 plant taxa that stuck around from 46,000 to 12,000 years ago, even though temperatures in the region fluctuated by some 20 °C during this period. "I was surprised that the [living] environment remained stable for so long," says Jørgensen (Molecular Ecology, DOI: 10.1111/j.1365-294x.2011.05287.x).

The result does not surprise Gregory Retallack at the University of Oregon in Eugene, who studies plant remains in ancient soils that have been fossilised. "A part of this stability is down to the inertia of ecosystems," he says.

Haile and colleagues are now keen to analyse other samples to uncover how the prehistoric flora and fauna in Canada and Alaska were affected by climate change.

Andrew Lowe at the University of Adelaide thinks the results could be used in climate models "to tell us how future communities will change". But Retallack thinks such predictions will not be possible until we know, for example, how the flora and fauna were affected by large pulses of warming 70,000 and 125,000 years ago.

Credit:
New Scientist
 
 

 Russians revive Ice Age flower from frozen burrow

2/21/2012 – It was a squirrel's a burrow containing fruit and seeds that had been stuck in the Siberian permafrost for over 30,000 years.

From the fruit tissues, a team of Russian scientists managed to resurrect an entire plant in a pioneering experiment that paves the way for the revival of other species.

The Silene stenophylla is the oldest plant ever to be regenerated, the researchers said, and it is fertile, producing white flowers and viable seeds.

The experiment proves that permafrost serves as a natural depository for ancient life forms, said the Russian researchers, who published their findings in Tuesday's issue of "Proceedings of the National Academy of Sciences" of the United States.

"We consider it essential to continue permafrost studies in search of an ancient genetic pool, that of pre-existing life, which hypothetically has long since vanished from the earth's surface," the scientists said in the article.

Canadian researchers had earlier regenerated some significantly younger plants from seeds found in burrows.

Svetlana Yashina of the Institute of Cell Biophysics of the Russian Academy Of Sciences, who led the regeneration effort, said the revived plant looked very similar to its modern version, which still grows in the same area in northeastern Siberia.

"It's a very viable plant, and it adapts really well," she told The Associated Press in a telephone interview from the Russian town of Pushchino where her lab is located.

She voiced hope the team could continue its work and regenerate more plant species.

The Russian research team recovered the fruit after investigating dozens of fossil burrows hidden in ice deposits on the right bank of the lower Kolyma River in northeastern Siberia, the sediments dating back 30,000-32,000 years.

The sediments were firmly cemented together and often totally filled with ice, making any water infiltration impossible — creating a natural freezing chamber fully isolated from the surface.

"The squirrels dug the frozen ground to build their burrows, which are about the size of a soccer ball, putting in hay first and then animal fur for a perfect storage chamber," said Stanislav Gubin, one of the authors of the study, who spent years rummaging through the area for squirrel burrows. "It's a natural cryobank."

The burrows were located 125 feet (38 meters) below the present surface in layers containing bones of large mammals, such as mammoth, wooly rhinoceros, bison, horse and deer.

Gubin said the study has demonstrated that tissue can survive ice conservation for tens of thousands of years, opening the way to the possible resurrection of Ice Age mammals.

"If we are lucky, we can find some frozen squirrel tissue," Gubin told the AP. "And this path could lead us all the way to mammoth."

Japanese scientists are already searching in the same area for mammoth remains, but Gubin voiced hope that the Russians will be the first to find some frozen animal tissue that could be used for regeneration.

"It's our land, we will try to get them first," he said.
 
 

 Record-Breaking Ice Core May Hold Key to Climate Variation

June 10, 2004     By Sarah Graham     for Scientific American

Scientists have successfully drilled through an Antarctic ice sheet to extract the longest ice core ever recovered, according to a report published today in the journal Nature. The cylinder of ice dates back nearly three quarters of a million years and will help researchers better understand our planet¿s history of cyclical climate variation. "This has the potential to separate the human-caused impacts from the natural and place it in a much clearer context," explains James White of the Institute of Arctic and Alpine Research at the University of Colorado at Boulder, who was not involved in the research but penned a commentary on the find for this week¿s issue of the journal Science.

An international collaboration known as the European Project for Ice Coring in Antarctica (EPICA) recovered the nearly three-kilometer-long core from a region of the East Antarctic ice sheet known as Dome C. The bottom of the 10-centimeter-wide cylinder dates to some 740,000 years ago and nearly doubles the reach of the next-longest ice core, which was drilled at Vostok, Antarctica, in the late 1990s and spanned the past 420,000 years. Temperature records for eight ice ages are documented in the new core. Of particular interest to climatologists is the complete record of the interglacial time period known as Marine Isotope Stage 11 (MIS11), which occurred around 400,000 years ago, a time when our planet's positioning was similar to its current orbital configuration. MIS11 lasted 28,000 years--considerably longer than the next three interglacial periods before present--and understanding its progression may help scientists better predict what¿s in store for the earth¿s future climate.

The core also reveals that not all ice ages are created equal. From the Vostok core, scientists deduced that those that occurred in the last 400,000 years were very intense, lasting around 80,000 to 100,000 years each. The new data suggest that earlier ice ages were shorter and the longer-lasting interglacial periods had lower temperatures, a finding that agrees with lower-resolution marine sediment cores. Because they have not yet reached the bottom of the ice sheet, the researchers hope that they will be able to extend the climate record even further back in time through continued drilling at the same site. Notes White: "The possibility of a million-year ice core is out there and a million years ago is a really significant period in the earth¿s climate history."

Scientific American
Permanent Address: http://www.scientificamerican.com/article/record-breaking-ice-core/
 

 

 

 

 

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