Eideard

Scientists say they can now explain the existence of what are perhaps Earth’s most extraordinary mountains.

The Gamburtsevs are the size of the European Alps and yet they are totally buried beneath the Antarctic ice. Their discovery in the 1950s was a major surprise. Most people had assumed the rock bed deep within the continent would be flat and featureless.

Survey data now suggests the range first formed over a billion years ago, researchers tell the journal Nature.

The Gamburtsevs are important because they are thought to be the location where the ice sheet we know today initiated its march across Antarctica. Unravelling the mountains’ history will therefore inform climate studies, helping scientists to understand not just past changes on Earth but possible future scenarios as well…

This multinational effort in 2008/2009 flew aircraft back and forth across the east of the White Continent, mapping the shape of the hidden mountain system using ice-penetrating radar. Other instruments recorded the local gravitational and magnetic fields, while seismometers were employed to probe the deep Earth.

The AGAP team believes all this data can now be meshed into a credible narrative for the Gamburtsevs’ creation and persistence through geological time…

“This research really solves the mystery of how you can have young-looking mountains in the middle of an old continent,” said US principal investigator Dr Robin Bell from the Lamont-Doherty Earth Observatory of Columbia University.

“In this case, the original Gamburtsevs probably completely eroded away only to come back, phoenix-like. They’ve had two lives,” she told BBC News…

The search also goes on for a suitable place in the range to drill for ancient ice.

By examining bubbles of air trapped in compacted snow, it is possible for researchers to glean details about past environmental conditions, including temperature and the concentration of gases in the atmosphere such as carbon dioxide.

Somewhere in the Gamburtsev region there ought to be a location where ices can be retrieved that are more than a million years old. This would be at least 200,000 years older than the most ancient Antarctic ice cores currently in the possession of scientists.

RTFA. Please. Another interesting addition to paleo-climatology and geology.

Thanks, Ursarodinia

The melting of glaciers is well documented, but when looking at the rate at which they have been retreating, a team of international researchers steps back and says not so fast.

Previous studies have largely overestimated mass loss from Alaskan glaciers over the past 40-plus years, according to Erik Schiefer, a Northern Arizona University geographer…

The research team, led by Étienne Berthier…says that glacier melt in Alaska between 1962 and 2006 contributed about one-third less to sea-level rise than previously estimated…

Schiefer said the team plans to use the same methodologies from the Alaskan study in other glacial regions to determine if further recalibrations of ice melt are in order. These techniques use satellite imagery that spans vast areas of ice cover.

Previous methods estimated melt for a smaller subset of individual glaciers. The most comprehensive technique previously available used planes that flew along the centerlines of selected glaciers to measure ice surface elevations. These elevations were then compared to those mapped in the 1950s and 1960s. From this, researchers inferred elevation changes and then extrapolated this to other glaciers.

Two factors led to the original overestimation of ice loss with this method, Schiefer said. One is the impact of thick deposits of rock debris that offer protection from solar radiation and, thus, melting. The other was not accounting for the thinner ice along the edges of glaciers that also resulted in less ice melt.

Schiefer and his colleagues used data from the SPOT 5 French satellite and the NASA/Japanese ASTER satellite and converted the optical imagery to elevation information. They then compared this information to the topographical series maps of glacial elevations dating back to the 1950s.

While the team determined a lower rate of glacial melt during a greater than 40-year span, Schiefer said other studies have demonstrated the rate of ice loss has more than doubled in just the last two decades.

The geographers expect that rate of acceleration to continue. But, like any solid science, establishing greater baseline accuracy always aids in understanding results, projections, predictions.