* Astronomy

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RE: Antarctic ice cores

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Antarctic ice core reveals how sudden climate changes in North Atlantic moved south

A new, highly detailed ice core retrieved by researchers with the National Science Foundation (NSF)-funded West Antarctic Ice Sheet (WAIS) Divide project reveals a consistent pattern of climate changes that started in the Arctic and spread across the globe to the Antarctic during planet Earth's last glacial period, tens of thousands of years ago.
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Title: Drilling deep in South Pole Ice
Author: Timo Karg, Rolf Nahnhauer

To detect the tiny flux of ultra-high energy neutrinos from active galactic nuclei or from interactions of highest energy cosmic rays with the microwave background photons needs target masses of the order of several hundred cubic kilometres. Clear Antarctic ice has been discussed as a favourable material for hybrid detection of optical, radio and acoustic signals from ultra-high energy neutrino interactions. To apply these technologies at the adequate scale hundreds of holes have to be drilled in the ice down to depths of about 2500 m to deploy the corresponding sensors. To do this on a reasonable time scale is impossible with presently available tools. Remote drilling and deployment schemes have to be developed to make such a detector design reality. After a short discussion of the status of modern hot water drilling we present here a design of an autonomous melting probe, tested 50 years ago to reach a depth of about 1000 m in Greenland ice. A scenario how to build such a probe today with modern technologies is sketched. A first application of such probes could be the deployment of calibration equipment at any required position in the ice, to study its optical, radio and acoustic transmission properties.

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The hunt is on for million-year-old ice core

A race is on to retrieve the first million-year-old sample from deep within Antarctica's ice. It's a prize that could help us understand what drives major changes in Earth's climate.
Every 100,000 years or so, the Earth swings into an ice age - but it wasn't always this way. Until around 1 million years ago, our planet danced to a faster beat, with the ice age pulses occurring every 40,000 years. No one knows why the tempo slowed.
Currently, the shifts between ice ages and warm interglacial phases are thought to be influenced by three cyclical changes to Earth's motion. The Earth's axis wobbles or "precesses" on a 26,000-year cycle; it changes its average tilt on a 41,000-year cycle; and it shifts its orbit from being roughly circular to more elliptical on a 100,000-year cycle.
These changes alter the intensity of sunlight hitting the Earth at high latitudes, and so affect the extent of glaciation. The puzzling thing about the shift that happened a million years ago is that there was no obvious change to any of these cycles to make it happen.
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Ice Cores Yield Rich History of Climate Change

On Friday, Jan. 28 in Antarctica, a research team investigating the last 100,000 years of Earth's climate history reached an important milestone completing the main ice core to a depth of 3,331 meters at West Antarctic Ice Sheet Divide (WAIS). The project will be completed over the next two years with some additional coring and borehole logging to obtain additional information and samples of the ice for the study of the climate record contained in the core.

As part of the project, begun six years ago, the team, funded by the National Science Foundation (NSF), has been drilling deep into the ice at the WAIS Divide site and recovering and analysing ice cores for clues about how changes in the concentration of greenhouse gases in the atmosphere have influenced the Earth's climate over time.

Blobrana · L

Deepest core drilled from Antarctic Peninsula; may contain glacial stage ice

Researchers here are hopeful that the new core they drilled through an ice field on the Antarctic Peninsula will contain ice dating back into the last ice age. If so, that record should give new insight into past global climate changes.
The expedition in early winter to the Bruce Plateau, an ice field straddling a narrow ridge on the northernmost tongue of the southernmost continent, yielded a core that was 445.6 metres long, the longest yet recovered from that region of Antarctica.
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Antarctic drilling project aims for a definitive record of climate.

"We're checking out history books made of ice" - Kendrick Taylor.

A palaeoclimatologist at the Desert Research Institute in Reno, Nevada, Taylor is the chief scientist of the West Antarctic Ice Sheet (WAIS) Divide drilling project, which is now three-quarters of the way towards pulling up the most temporally precise record of carbon dioxide for the past 100,000 years. The highly anticipated ice core promises to improve climatologists' understanding of the dynamic global climate system, and has already begun to illuminate how humans can affect it.
On 25 January, drillers finished the season at a depth of 2,561 metres, about a kilometre off the project's final goal. Relentless winds and poor visibility at the WAIS Divide camp, about 1,170 kilometres from the South Pole, had permitted only 35 days of drilling this year.

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Title: Evidence for warmer interglacials in East Antarctic ice cores
Authors: Louise C. Sime, Eric W. Wolff, Kevin I. C. Oliver and Julia C. Tindall

Ice cores are unique climate records, allowing scientists to investigate climate changes over hundreds of thousands of years. The Earth's oldest ice is found in East Antarctica. The three oldest existing ice cores were drilled at Dome C, Dome F and Vostock. The longest ice core - at 3,650 metres - comes from Vostock, but the oldest ice core, drilled by the European Project for Ice Coring in Antarctica (EPICA) team, contains a climate record stretching back 800,000 years. Analysis of the ice cores has revolutionized our understanding of how Antarctic climate has varied in the past. Information from ice cores is vital for testing and improving the computer models used to predict future climate.
Interglacials recur roughly every 100,000 years between ice ages. The present warm period began around 10,000 years ago and has been relatively stable.
Direct sea level measurements based upon coastal sedimentary deposits and tropical coral sequences have established that global sea level was higher than present during the last interglacial (~125,000 years ago) by approximately 4 to 6 m. This indicates that the Greenland and Antarctic ice-sheets were smaller than during the present day.
The authors analysed 340,000 years of oxygen and hydrogen isotope data from three ice core sites across East Antarctica, alongside isotope-enabled general circulation model results.

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Blobrana · L

The oldest ice core retrieved from Antarctica - and the world - travels back about 850,000 years in time, revealing eight previous ice ages. It took the European Project for Ice Coring in Antarctica (EPICA) External Non-U.S. government site more than five field seasons to drill down 3,270 metres into the East Antarctic ice sheet.
Andrei Kurbatov External Non-U.S. government site and his colleagues believe that they can retrieve a nearly limitless supply of ice for climate research that dates back at least 2.5 million years - located right at the surface and retrievable in a single season.

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Ice cores