Ice Sheet – sunshine hours

Earth’s Internal Heat Drives Subglacial Melting in Greenland

Published on April 5, 2016April 5, 2016 by sunshinehours1Leave a comment

This is pretty amazing.

Greenland’s lithosphere has hot depths which originate in its distant geological past and cause Greenland’s ice to rapidly flow and melt from below.

To understand Greenland’s ice of today researchers have to go far back into Earth’s history. The island’s lithosphere has hot depths which originate in its distant geological past and cause Greenland’s ice to rapidly flow and melt from below. An anomaly zone crosses Greenland from west to east where present-day flow of heat from the Earth’s interior is elevated. With this anomaly, an international team of geoscientists led by Irina Rogozhina and Alexey Petrunin from the GFZ German Research Centre for Geosciences could explain observations from radar and ice core drilling data that indicate a widespread melting beneath the ice sheet and increased sliding at the base of the ice that drives the rapid ice flow over a distance of 750 kilometres from the summit area of the Greenland ice sheet to the North Atlantic Ocean.

The North Atlantic Ocean is an area of active plate tectonics. Between 80 and 35 million years ago tectonic processes moved Greenland over an area of abnormally hot mantle material that still today is responsible for the volcanic activity of Iceland. The mantle material heated and thinned Greenland at depth producing a strong geothermal anomaly that spans a quarter of the land area of Greenland. This ancient and long-lived source of heat has created a region where subglacial meltwater is abundant, lubricating the base of the ice and making it flow rapidly. The study indicates that about a half of the ice in north-central Greenland is resting on a thawed bed and that the meltwater is routed to the ocean through a dense hydrological network beneath the ice.

The team of geoscientists has now, for the first time, been able to prove strong coupling between processes deep in the Earth’s interior with the flow dynamics and subglacial hydrology of large ice sheets: “The geothermal anomaly which resulted from the Icelandic mantle-plume tens of millions of years ago is an important motor for today’s hydrology under the ice sheet and for the high flow-rate of the ice” explains Irina Rogozhina. “This, in turn, broadly influences the dynamic behaviour of ice masses and must be included in studies of the future response to climate change.”

Antarctica GAINING 82 to 112 gigatons of Ice per Year

Published on October 31, 2015 by sunshinehours14 Comments

“According to the new analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed to 82 billion tons of ice per year between 2003 and 2008.”

“Zwally’s team calculated that the mass gain from the thickening of East Antarctica remained steady from 1992 to 2008 at 200 billion tons per year”

“The good news is that Antarctica is not currently contributing to sea level rise, but is taking 0.23 millimeters per year away,” Zwally said.”

http://www.nasa.gov/feature/goddard/nasa-study-mass-gains-of-antarctic-ice-sheet-greater-than-losses

Antarctica , Sea Ice, Ice Sheets and Wind Excuses

Published on August 31, 2014August 31, 2014 by sunshinehours11 Comment

Over at the LA Times they are making excuses for why there is record breaking sea ice in Antarctica.

One of the excuses is that “global warming is strengthening circumpolar winds”. There is very little evidence that “global warming” would actually increase wind. Any change in winds is tenuous and could be cyclic.

However, the trouble with that excuse is that an increase (or change caused by cycles like the AMO/PDO etc) in circumpolar wind in Antarctica would prevent snow accumulation and cause ablation of the ice surface which would then appear as “melting” and it would be nothing of the sort.

http://www.nature.com/ngeo/journal/v6/n5/full/ngeo1766.html