September 9, 2013
British Antarctic Survey To Launch Ambitious Survey Of Pine Island Glacier
Lawrence LeBlond for redOrbit.com - Your Universe Online
An ambitious science mission is about to begin in Antarctica, with team members from the British Antarctic Survey (BAS) looking to understand why the continent’s Pine Island Glacier (PIG), located on the West Antarctic Ice Sheet, is rapidly diminishing.
The mission, which will be broken down into four distinct programs, is set to depart shortly and expected to officially begin when the Antarctic summer season approaches later this year. The National Environment Research Council-funded iSTAR program consists of the Ocean2Ice (iSTAR A), Ocean Under Ice (iSTAR B), Dynamic Ice (iSTAR C), and Ice Loss (iSTAR D) missions. The iSTAR program is being led by Science Programme Manager Dr. Andy Smith of the BAS.
Speaking on the topic of Antarctic ice loss at this week’s British Science Festival, Dr. Smith had this to say:
“We used to think that the volume of water flowing from Antarctica’s melting glaciers and icebergs into the ocean was equal to the amount of water falling as snow onto the ice sheet; and that this process was keeping the whole system in balance. But Pine Island and Thwaites glaciers on the West Antarctic Ice Sheet (WAIS) are losing ice at a faster rate than they are being replenished. This affects sea level all over the world. The speed of changes to this region has taken scientists by surprise and we need to find out what’s going on.”
The BAS hopes its iSTAR program will provide invaluable insights into the behavior of the PIG. The program will include not only numerous experts in the field, but also diverse techniques and technologies, including robotic subs and satellites. The team will also incorporate the help of instrument-carrying elephant seals. The teams will measure changes to the flow and thickness of the PIG and investigate the role the ocean plays in transporting warm water beneath the ice shelf.
The first group of scientists will depart the UK and spend 10 weeks traveling 600 miles across the ice sheet by "tractor-traverse." This team will utilize ground-based radar and seismic technologies to map the bed beneath PIG. The team hopes this will reveal the influence that the glacier’s bed conditions have on varying the flow and thickness of ice from the ice shelf up into the tributaries. In areas that are inaccessible from the ground, the team will rely on satellite remote sensing technology to measure changes in the glacier.
At the beginning of 2014, a second team will sail into the Amundsen Sea aboard the RRS James Clark Ross, where they will spend 30 days placing instruments and devices into the ocean around PIG, in the hopes they can discover when, where, and how warm ocean water gets close to the ice. These observations will be important for improving computer models used by science to forecast future climate and sea level changes.
Furthering the research, another team will incorporate a fleet of oceanic robots (Seagliders) to measure the temperature, saltiness and current speeds of the water at differing depths. Each time a Seaglider reaches the ocean surface it will transmit data using satellite phone technology. This information can then be used to work out how the warm waters are reaching the ice shelf and whether it is likely to continue.
When the Antarctic winter returns, the building sea ice will prevent researchers from continuing to carry out missions with the Seagliders. So, the team will also incorporate the use of seals. To continue the mission into winter months, 15 seals will be outfitted with small sensors that will capture information and then transmit it back to researchers via satellite technology. This research will also benefit biologists looking to understand how seals react to climate change. The sensors on the seals are only temporary and fall off when the marine mammals moult their fur.
In another iSTAR program, researchers will utilize an unmanned submarine (Autosub), that can dive deep beneath the sea ice, measuring along pre-defined areas before returning with data. The Autosub will measure gradual changes in ice thickness using four autonomous radar instruments that have been designed for year-round operations. This investigation will help scientists determine how heat is transported beneath the ice shelf by ocean currents and what impact changes in the climate will have on this region of Antarctica.
"We want to improve our understanding of what this glacier is doing and to use that information to be able to make good predictions for its contribution to global sea level in the years ahead… And if we can do that, if we can make those good predictions, then we'll also have some tools to apply to the rest of the Antarctic and the Greenland ice sheet as well," Dr. Smith said in an interview with the BBC’s Jonathan Amos.
Pine Island Glacier is vast. It runs alongside the Hudson mountains into the Amundsen Sea, draining an area covering more than 96,000 square miles – about one quarter the size of the US. It has also been known to produce massive icebergs, such as the 45-square-mile “ice island” that broke away from the glacier this past July.
PIG is also a difficult glacier to study due to its remoteness. Scientists have only just realized within the past 20 years that the glacier is undergoing significant changes. This evidence may have gone unnoticed if it weren’t for high-tech satellites. Satellites have shown that the rate at which PIG is losing its mass is doubling about every five years.
Warming waters in the Southern Ocean has been blamed for most of this ice loss. The warm ocean waters are continuously eating away at the underbelly of the PIG’s ice shelf, causing the grounding line – the point where the ice shelf starts to become buoyant – to pull back farther and farther toward the land.
The iSTAR program will hopefully determine if these changes are expected to continue, or if they will reverse, eventually allowing the ice shelf to heal.
“We are attempting to tackle this big science question from a number of different ice and ocean perspectives. Our observations and measurements will be a major contribution to the on-going, and urgent, international scientific effort to understand our changing world. We are confident that our results will bring many benefits to science, to policy and to economic decision-making — which will ultimately contribute to the well-being of our society,” said Professor Karen Heywood, a principal investigator of one of the iSTAR missions from University of East Anglia.
The $11.6 million (US) iSTAR program has been funded by the National Environment Research Council (NERC) and is expected to take six years to complete.
Autosub was designed and built by engineers at NERC’s National Oceanographic Centre and has already proved itself on previous missions below the PIG in 2009.