* Astronomy

Blobrana · L

RE: Greenland

Blobrana · L

Scientists have discovered what they think may be another reason why Greenland 's ice is melting: a thin spot in Earth's crust is enabling underground magma to heat the ice.
They have found at least one hotspot in the northeast corner of Greenland -- just below a site where an ice stream was recently discovered.
The researchers don't yet know how warm the hotspot is. But if it is warm enough to melt the ice above it even a little, it could be lubricating the base of the ice sheet and enabling the ice to slide more rapidly out to sea.
Timothy Leftwich, von Frese's former student and now a postdoctoral engineer at the Centre for Remote Sensing of Ice Sheets at the University of Kansas, presented the study's early results on Thursday, December 13, 2007, at the American Geophysical Union meeting in San Francisco.
von Frese's team combined gravity measurements of the area taken by a Naval Research Laboratory aircraft with airborne radar measurements taken by research partners at the University of Kansas. The combined map revealed changes in mass beneath the Earth's crust, and the topography of the crust where it meets the ice sheet.
Below the crust is the mantle, the partially molten rocky layer that surrounds the Earth's core. The crust varies in thickness, but is usually tens of miles thick. Even so, the mantle is so hot that temperatures just a few miles deep in the crust reach hundreds of degrees Fahrenheit, von Frese explained.

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Blobrana · L

An international team of researchers including Murdochs molecular biology and biotechnology lecturer Dr Michael Bunce has published a report in the journal Science showing ancient DNA from ice cores can yield valuable information about past environments.
DNA from deep ice cores under the Greenland icecap, dating back more than 450,000 years, revealed Greenland now lying below kilometres of thick ice was once inhabited by a diverse array of conifer trees and insects.
Dr Bunce said low temperatures below the ice meant the DNA has been well preserved and is some of the oldest DNA to be isolated to date.

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Blobrana · L

Top Gear Polar Special - BBC - The best bits

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Armies of insects once crawled through lush forests in a region of Greenland now covered by more than 2000m of ice.
DNA extracted from ice cores show that moths and butterflies were living in forests of spruce and pine in the area between 450,000 and 800,000 years ago.
Writing in the journal Science, the researchers say they believe the DNAs are the oldest pure samples obtained.

SAMPLE SITES

    * Dye 3: 2km long ice core
    * Greenland Ice Core Project (GRIP): 3km long ice core
    * John Evans Glacier (JEG): Control site
    * Kap Kobenhavn: Previously youngest known Greenland forest

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-- Edited by Blobrana at 14:35, 2007-07-06

Blobrana · L

A team of international researchers has collected the oldest samples of DNA ever recovered and used them to show Greenland was much warmer during the last Ice Age than previously believed.
The ancient DNA was discovered at the bottom of a two-kilometre-thick ice sheet and comes from the trees, plants and insects of a boreal forest estimated to be between 450,000 and 800,000 years old. Previously, the youngest evidence of a boreal forest in Greenland was from 2.4 million years ago.
The results findings appear today in the journal Science.

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The Earth had glaciers in parts of the northern hemisphere as far back as 38 million years ago, much earlier than was previously thought.
That is the conclusion of University of Southampton scientists based at the National Oceanography Centre, Southampton (NOCS), reported online by the science journal Nature this week.
The research indicates for the first time that there was glacial ice, probably of restricted extent, on Greenland during a time when CO2 levels are thought to have been significantly higher than pre-industrial levels. The findings therefore have implications for our understanding of future climate change in an increasingly CO2-rich world. The next task is to investigate ice extent and stability during this geological analogue for the future.
The Earth went through a profound change in climate during the transition between the Eocene and Oligocene periods (around 34 million years ago) when the Antarctic ice sheets expanded to close to their modern size. But the existence of northern polar ice had only previously been demonstrated back to the Miocene period (around 15 million years ago).
The new research provides evidence for an earlier development of northern hemisphere ice, linked to glaciers on East Greenland which are identified as the likely source of `ice-rafted' debris found in sediments drilled from the Norwegian-Greenland Sea and dated as being between 38 and 30 million years old.
The debris consists of pebbles and mineral grains showing characteristic surface features indicating that they were frozen into glacial ice which subsequently calved as icebergs at the coast. Then, as the icebergs melted, the rock debris was shed into the water column and subsequently incorporated in seafloor sediments. Surface textures and size distributions indicate that the ice-rafted debris was glacial in origin (melted from continental ice) rather than shed from sea ice.
James Eldrett, Ian Harding, Paul Wilson, Emily Butler and Andrew Roberts, all of the University of Southampton's School of Ocean and Earth Science, which is based at NOCS, used ice-rafted debris (IRD) analysis, photographic, electron microscopic, geochemical and rock magnetic techniques in their research which was partially funded by the Natural Environment Research Council.

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Blobrana · L

In the first test of a new radar instrument, scientists have seen through more than a mile of Greenland ice to reveal an image of land that has been hidden for millions of years.
Ohio State University scientists and their colleagues will use what they learn from the instrument, dubbed GISMO (for Global Ice Sheet Mapping Orbiter), to determine how global climate change will affect the ice.

"One of the key things we need to know to predict how the ice sheet is going to change in the future is the distribution -- and the change in distribution -- of sub-glacial water. So our dream is to create this new image of what Greenland would look like, were the ice sheets stripped away" - Ken Jezek, professor of earth sciences at Ohio State.

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