Javelin-Hurling Scientists Measure Antarctic Glacier Melt

How quickly are glaciers in Antarctica melting? Researchers are launching javelin-shaped devices out of airplanes to help answer that question and find out what's going on in some of the frozen continent's most inaccessible places.

So far, scientists have deployed about 25 of these GPS-equipped javelins in Antarctica's Pine Island Glacier, and another four on the Antarctic Peninsula, said Hilmar Gudmundsson, a researcher at the British Antarctic Survey (BAS). The javelins will automatically record and relay their positions for two to three years, allowing researchers to figure out how quickly the glacier is flowing into the ocean. Preliminary measurements show that the Pine Island Glacier's march to the sea is speeding up, Gudmundsson told OurAmazingPlanet.

The Pine Island Glacier is thinning faster than any other glacier in Antarctica, and it's important to find out why and exactly how fast, Gudmundsson said. By some estimates, this glacier alone could be responsible for about 5 percent of global sea level rise, although that is a rough calculation and varies by year, he added.

The javelins are designed to only partially embed into the ice, so that they are still able to communicate with satellites. To that end the devices are equipped with small parachutes and "ice brake" fins to keep them from disappearing beneath the ice sheet when they crash land, Gudmundsson said.

Like many glaciers in polar regions, the Pine Island Glacier's expanse of ice doesn't stop when it reaches the ocean. Instead, the ice flows into the sea, where it floats atop the water, forming a platform of ice called an ice shelf. Measurements have shown that the Antarctic Ocean is warmer than it used to be, and is melting the bottom of this ice shelf. That produces less resistance for the glacier on land, which, as a result, slides toward the ocean faster than before, Gudmundsson said.

And behind the Pine Island Glacier is an even larger section of the West Antarctic Ice Sheet, one of the largest in the world. The glacier acts like a plug in a leaky dam, and if it collapses, it could have devastating consequences for global sea levels, he added.

The javelins Gudmundsson and his team have deployed allow researchers to measure areas, like this one, that are difficult to access over land. "This opens up new possibilities. We can instrument areas that were previously out of reach," he said. "These data will give us a clear picture of what's going on but will also give us a valuable data set to test our [computer] models."

Email Douglas Main or follow him @Douglas_Main. Follow us @OAPlanet, Facebook or  Google+. Original article on LiveScience's OurAmazingPlanet.

• Album: Stunning Photos of Antarctic Ice
• Antarctica: 100 Years of Exploration (Infographic)
• Antarctica's Pine Island Glacier Is Rifting | Video

Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

View the original article here

Seals take scientists to Antarctic's ocean floor

SYDNEY (Reuters) - Elephant seals wearing head sensors and swimming deep beneath Antarctic ice have helped scientists better understand how the ocean's coldest, deepest waters are formed, providing vital clues to understanding its role in the world's climate.

The tagged seals, along with sophisticated satellite data and moorings in ocean canyons, all played a role in providing data from the extreme Antarctic environment, where observations are very rare and ships could not go, said researchers at the Antarctic Climate & Ecosystem CRC in Tasmania.

Scientists have long known of the existence of "Antarctic bottom water," a dense, deep layer of water near the ocean floor that has a significant impact on the movement of the world's oceans.

Three areas where this water is formed were known of, and the existence of a fourth suspected for decades, but the area was far too inaccessible, until now, thanks to the seals.

"The seals went to an area of the coastline that no ship was ever going to get to," said Guy Williams, ACE CRC Sea Ice specialist and co-author of the study.

"This is a particular form of Antarctic water called Antarctic bottom water production, one of the engines that drives ocean circulation," he told Reuters. "What we've done is found another piston in that engine."

Southern Ocean Elephant seals are the largest of all seals, with males growing up to six meters (20 feet) long and weighing up to 4,000 kilograms (8,800 lbs).

Twenty of the seals were deployed from Davis Station in east Antarctica in 2011 with a sensor, weighing about 100 to 200 grams, on their head. Each of the sensors had a small satellite relay which transmitted data on a daily basis during the five to 10 minute intervals when the seals surfaced.

"We get four dives worth of data a day but they're actually doing up to 60 dives," he said.

"The elephant seals ... went to the very source and found this very cold, very saline dense water in the middle of winter beneath a polynya, which is what we call an ice factory around the coast of Antarctica," Williams added.

Previous studies have shown that there are 50-year-long trends in the properties of the Antarctic bottom water, and Williams said the latest study will help better assess those changes, perhaps providing clues for climate change modeling.

"Several of the seals foraged on the continental slope as far down as 1,800 meters (1.1 miles), punching through into a layer of this dense water cascading down the abyss," he said in a statement. "They gave us very rare and valuable wintertime measurements of this process."

(Reporting by Pauline Askin, Editing by Elaine Lies and Michael Perry)

View the original article here