Antarctic sea ice much thicker than expected

The British Antarctic Survey has issued a press release regarding the use of a robot submarine which has been measuring the thickness of Antarctic sea ice. The submarine can operate at upto 30m depth and maps the sea ice from underneath. They found that, on average, the thickness of the ice beneath sea level was much greater than previously thought at 1.4 to 5.5m, with the thickest sea ice measured at 16m. They also encountered a lot of highly deformed ice, where one block had ridden over another, increasing the overall draft.

“We suggest that thick ice in the near-coastal and interior pack may be under-represented in existing in situ assessments of Antarctic sea ice and hence, on average, Antarctic sea ice may be thicker than previously thought.”

No doubt some will contort their theories and themselves to show how increased sea ice thickness and greatly increased ice cover in the Antarctic are perfectly consistent with global warming. I am inclined to the much more parsimonious explanation that increased freezing is always a sign of cooling.

The first detailed, high-resolution 3-D maps of Antarctic sea ice have been developed using an underwater robot. Scientists from the UK, USA and Australia say the new technology provides accurate ice thickness measurements from areas that were previously too difficult to access. …

Now, with the Autonomous Underwater Vehicle (AUV) known as SeaBED, scientists have an invaluable new tool to fill this gap.

While most oceanographic survey instruments look down at the seafloor, SeaBED was fitted with an upward-looking sonar in order to measure and map the underside of sea ice floes. The AUV operated at a depth of 20 to 30 meters and was driven in a lawnmower pattern. These lines of data were merged to form high-resolution 3D bathymetric surveys of the underside of the ice.

Photo

SeaBed vehicle recovery Photo P. Kimball / Woods Hole Oceanographic Institution

 

The yellow SeaBED robot, which is approximately two meters long and weighs nearly 200 kilograms, has a twin-hull design that gives the robot enhanced stability for low-speed photographic surveys. …….. 
The research was carried out by scientists at the Institute of Antarctic and Marine Science (Australia), Antarctic Climate and Ecosystem Cooperative Research Centre (Australia), Woods Hole Oceanographic Institution (USA) and British Antarctic Survey (UK).

Live Science:

Not only is the amount of sea ice increasing each year, but an underwater robot now shows the ice is also much thicker than was previously thought, a new study reports.

The discovery adds to the ongoing mystery of Antarctica’s expanding sea ice. According to climate models, the region’s sea ice should be shrinking each year because of global warming. Instead, satellite observations show the ice is expanding, and the continent’s sea ice has set new records for the past three winters. At the same time, Antarctica’s ice sheet (the glacial ice on land) is melting and retreating. …….

The findings were published today (Nov. 24) in the journal Nature Geoscience. ….. 

The sea ice growth around Antarctica has averaged about 1.2 percent to 1.8 percent per decade between 1979 and 2012, according to the 2013 Intergovernmental Panel on Climate Change’s Fifth Assessment Report. The increases are concentrated primarily in the Ross Sea in western Antarctica. Sea ice in the nearby Bellingshausen and Amundsen seas has significantly decreased. Researchers suspect these regional differences could result from stronger winds or increased meltwater from the Antarctic ice sheet, or a combination of both factors.

Tags: , , ,


%d bloggers like this: