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RE: Iceage melt
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Super-sensitive satellites have revealed the "ghosts" of the ancient glaciers that covered Canada 20,000 years ago and still haunt the country's landscape.
They show the ice was not a uniform blanket, as many believe, but had two massive domes, one on either side of Hudson Bay.

"We are seeing the ghosts of the ancient ice sheet, and that ice sheet had a lot of topography on it" -  geophysicist Jerry Mitrovica, of the University of Toronto.

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Arctic Ocean Pingos
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According to a recent paper published by MBARI geologists and their colleagues, methane gas bubbling through seafloor sediments has created hundreds of low hills on the floor of the Arctic Ocean. These enigmatic features, which can grow up to 40 metres  tall and several hundred meters across, have puzzled scientists ever since they were first discovered in the 1940s.
"Pingos," small, dome-shaped, ice-cored hills, are found in many Arctic regions. "Pingo-like features" are similar in shape and size to pingos on land, but are found underwater, on the continental shelf in several parts of the Arctic. Previous studies have suggested that pingo-like features are pingos that formed on land but were submerged when sea level rose following the end of the last ice age, over 10,000 years ago.

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New ice age theory
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Ice ages are not caused by planet Earth’s orbital variations as once thought, but by the dimmer switch inside the sun that causes its brightness to rise and fall on timescales of around 100,000 years which is exactly the same period as between ice ages on Earth, according to a radical new theory proposed by renowned astrophysicist  Robert Ehrlich of George Mason University.
Ehrlich modelled the effect of temperature fluctuations in the sun's interior and showed that while the temperature of the sun's core is held constant by the opposing pressures of gravity and nuclear fusion, slight variations are possible.
His research builds upon the work of Attila Grandpierre and Gábor Ágoston who calculated that magnetic fields in the sun's core could produce small instabilities in the solar plasma inducing localised oscillations in temperature.
In an article appearing in the journal Nature, Ehrlich describes how some of these oscillations reinforce one another and become long lasting temperature variations, with the sun's core temperature to oscillating around its average temperature of 13.6 million kelvin in cycles lasting either 100,000 or 41,000 years.
According to the scientist random interactions within the sun's magnetic field could flip the fluctuations between the two cycles which correspond to the Earth's ice ages.
Over the past million years, ice ages have occurred roughly every 100,000 years and before that roughly every 41,000 years.

Source

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RE: Iceage melt
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In one of the most stark illustrations of how a changing climate can have regional effects, scientists have learned that winds over North America have done a complete 180 since the time of the last Ice Age several thousand years ago.
Winter blizzards and spring thunderstorms today are usually fuelled by moisture-laden winds blowing in from the West Coast.

In this study, we found evidence that during the last glacial period, about 14,000 to 36,000 years ago, the prevailing wind in this zone was easterly, and marine moisture came predominantly from the East Coast” - lead study author Xiahong Feng of Dartmouth College.

The findings were detailed today in the online edition of the journal Geology.

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Antarctic warm periods
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From a distance, the Andrill operation appears out of nowhere, like a mirage: a white-draped tower amid giant blue boxcars laid out on a frozen sea.
But this mammoth venture to drill through ice, ocean and back through time is as real as a science lab and as practical as an oil rig: hard-hatted drillers and scientists work in concert to find clues about a time when Antarctica was warm and wet.
Because the researchers are convinced that a warmer age is in prospect as a result of human-spurred global climate change, they want to know what things were like ten million years ago, when warmer periods tended to wax and wane on the southernmost continent.

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New Zealand icebergs
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Ships near southern New Zealand have been warned of icebergs after several - some bigger than houses - were reported within 76 kilometres of the coast.
One iceberg, reported by a fishing boat to be 200 metres long and 50m high, was headed toward the South Island's east coast.

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Iceberg seabed scours
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New Zealand scientists have identified what appear to be ancient iceberg scours on the seabed off New Zealand's east coast.
Scientists from New Zealand National Institute of Water & Atmospheric Research (NIWA) said the large scours showed up on maps of the seabed produced from surveys of the Chatham Rise in August as part of the Government's Ocean Survey 20/20 research program.

"Grooves measuring about 2-2.5km long, 200 meter across and 10 meter deep, can be seen in the seabed on the eastern Chatham Rise, at a water depth of about 450-470 meters" - Scott Nodder, NIWA marine geologist who led the Chatham/Challenger Biodiversity Project onboard NIWA's deepwater research vessel Tangaroa in August.

The grooves were probably caused by an iceberg that carved off the Antarctic icesheet during the last Ice Age 18,000 to 20,000 years ago.
According to NIWA oceanographer Dr Mike Williams, the iceberg that made these scours would have been somewhere in the range of 2-5km long.
The scientists hope to take sediment samples from the scours to confirm their origin during the next Ocean Survey 20/20 voyages in April and June 2007.

Source Xinhua

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The Iceage
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The rise of the Appalachian Mountains seems to have triggered an ice age 450 million years ago by sucking CO2 from the atmosphere. Researchers report evidence that minerals from the mountain range washed into the oceans just before the cold snap, carrying atmospheric carbon dioxide with them. The result clarifies a long standing paradox in the historical relationship between CO2 and climate, experts say.
At the start of the so-called Ordovician ice age, about 450 million years ago, the planet went from a state of greenhouse warmth to one of glacial cold, culminating in mass extinctions of ocean life. This period has always posed a problem for climate modellers, notes geologist Matthew Saltzman of Ohio State University.

"The models for CO2 that span that interval have always shown levels that are much too high to have an ice age. That was a real paradox."

Researchers believe that the last ice age, which began 40 million years ago, was kicked off by the rise of the Himalayas during the collision of tectonic plates and a corresponding plunge in atmospheric carbon dioxide. Ocean deposits of calcium carbonate, or limestone, indicate that CO2-rich rainwater stripped calcium and strontium from the Himalayan rock; these elements fused with the carbon dioxide and spilled into the sea, effectively pulling carbon from the atmosphere.

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RE: Iceage melt
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A massive glacier relic from the Quaternary Period has been found in Shangyu, a city of Zhejiang Province, China. The announcement was made on August 26 by Han Tonglin, a Chinese glacier expert who has been doing field work in Shangyu.

Han Tonglin, a researcher at the Chinese Academy of Geological Sciences, inspected Mountain Fuzhi in Shangyu with other researchers between August 23 and 26. The mountain is very close to Hangzhou Bay, which looks out to the East China Sea. They found a large number of glacial landforms, such as u-shaped valleys, cirques, unusual glacier boulders, moraine gravel and glacial depression.
They were able to deduce that these landforms were formed by the growth and corrosion of an ancient glacier that existed during the ice age of the Quaternary Period, between two and three million years ago.

Source People's Daily

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Ice-age Cycles
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In the early 20th century, Milutin Milankovitch, a leading astronomer and climatologist of the time, proposed that the Earth's ice-age cycles could be predicted because they correspond directly with routine changes in the Earth's orbit and its tilt over cycles of tens of thousands of years.

Because of these changes, there are predictable variations in the amount of solar radiation striking the Earth's surface. Milankovitch argued that low levels of summer radiation permit snow to accumulate as permanent ice, while high levels of solar radiation melt snow and ice.
It all seemed so clean and simple.
And indeed the hypothesis was partially confirmed in the 1970s from marine sediment records extending through 2.75 million years of northern hemisphere ice-age cycles. As Milankovitch predicted, ice grew and melted at cycles of 23,000 and 41,000 years. But two observations were unexpected: from 2.75 until 0.9 million years ago, the ice sheets grew and melted almost entirely at the 41,000-year cycle. Since then, an oscillation near 100,000 years has dominated.
This knocked Milankovitch's theory for a loop.
Scientists have since turned to changes in atmospheric carbon dioxide as a possible explanation. Carbon dioxide concentrations can be measured in ancient air bubbles preserved in sequences of cores drilled into the Antarctic ice sheet. Because some changes in carbon dioxide have been found to occur slightly before changes in ice volume, the prevailing interpretation has been that carbon dioxide is an additional independent 'driver' of the size of ice sheets, along with solar radiation.
Now, a new hypothesis inverts this view.
William Ruddiman, an environmental scientist with the University of Virginia, provides a novel explanation for the rhythms of the ice ages in a paper just published online in the journal Climate of the Past. Ruddiman found that carbon dioxide is a driver of ice sheets only at the relatively small 23,000-year cycle, but not at the much larger ice-volume cycles at 41,000 years and approximately 100,000 years. In those cases he found that ice sheets instead control atmospheric carbon dioxide and drive feedbacks that amplify ice growth and melting. He says his carbon dioxide feedback hypothesis explains why the strongest cycles of ice response are not in correspondence with those in the orbital cycles.
Ruddiman concludes (as Milankovitch proposed) that ice sheets are initially driven by the Sun, but then the ice takes control of carbon dioxide changes, producing its own positive feedback (the amplifying effect) at the 41,000-year cycle.

This enhancement explains the strength of the 41,000-year ice-sheet changes over the first two-thirds of the ice ages. But over time, as polar climate cooled, summer melting weakened. During the last 0.9 million years, ice sheets have continued to grow at the 41,000-year cycle, but some of the new ice remained in place to help build larger ice sheets. Ice build-up continued until unusually large solar radiation peaks triggered rapid melting at intervals of 85,000 to 115,000 years. Although solar radiation peaks were the initial trigger for these melting episodes, most of the ice was removed by feedbacks in the climate system, and CO2 feedback was the largest of these.

"The origin of the ice-age cycles has been a major mystery in studies of past climates, and some scientists felt the answer must be very complex. Yet this hypothesis is quite simple, requiring only the Sun, the carbon dioxide feedback, and a gradual cooling. The prominent role proposed for carbon dioxide is consistent with its likely effect on future climate." - William Ruddiman.

Source: University of Virginia

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