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Scientists Forge through Severe Sea Ice to Better Determine Why Antarctica’s Glaciers are Collapsing [Slide Show]

Cold clues reveal how fast ice is disappearing, and therefore how quickly sea level could rise

By Douglas Fox

1 of 12

TREACHEROUS SEA:

Fragmented sea ice, or pack ice, seen from the deck of the icebreaker, Nathaniel B. Palmer . Heavy sea ice in the Weddell Sea, on the east side of the Antarctic Peninsula, makes navigation extremely difficult even for large icebreakers.....[ More ]

VANISHING ACT

Geologist Greg Balco from the Berkeley Geochronology Center collects rock samples from a mountain overlooking Sjögren Fjord on the Antarctic Peninsula. By measuring a rare isotope in the rock, Balco can determine how long the rock has been exposed to sunlight—and therefore how recent it was that thick Ice Age glaciers last covered this peak.....[ More ]

ODDBALL:

This granite boulder does not match the surrounding bedrock. A glacier transported it to this location thousands of years ago, and later dropped it here as the ice receded. These rocks, called glacial erratics, can be used to map the flow of ancient glaciers.....[ More ]

GLACIAL SCARS:

The bedrock on a mountain overlooking Sjögren Glacier is covered in scrape marks left by the glacier when it was much thicker and skidded over the mountain long ago. The orientation of the scars reveals the direction that the glacier flowed.....[ More ]

MELT UNDER WATER

A sensor is lowered through 700 meters of sea water filling a fjord on the Antarctic Peninsula. The sensor will measure temperature, salinity and the speed and direction of currents as it descends—allowing scientists to map the plumes of fresh meltwater bleeding off of coastal tidewater glaciers.....[ More ]

SEAFLOOR SAMPLE:

Workers on the rear deck of the Nathaniel B. Palmer haul in a four-meter-long core of sediment that was extracted from the seafloor 1,300 meters below. Sediment cores can provide a record of when the area was covered by a floating ice shelf or even by a gigantic, grounded glacier that rested on the seafloor.....[ More ]

MICROSCOPIC SHELLS:

The shells of tiny organisms, called foraminifera, that lived thousands of years ago are found in sediment cores taken from the sea floor. Scott Ishman, a paleoecologist from Southern Illinois University, studies them as ancient environmental markers.....[ More ]

WARM DWELLER:

This silica shell of an ancient diatom found in a sediment core taken from the seafloor off the Antarctic Peninsula in only. Amy Leventer, a paleobiologist at Colgate University, uses diatoms as proxies of past environments in Antarctica.....[ More ]

SHAPE CHANGER:

A mishmosh of microscopic diatom shells, thousands of years old, was found in certain seafloor sediments off the coast of Antarctica. The big, angular, rod-like diatom at the center, Eucampia antarctica , grows in different shapes depending on the amount of sea ice.....[ More ]

PARKED IN THE ICE:

A team of researchers disembarks from the icebreaker to take samples. The researchers will quantify pockets of melt water in the sea ice, and identify microscopic diatoms locked inside the ice.....[ More ]

A MIDSUMMER'S NIGHT:

Scientists are lowered by the ship's crane. By studying the thickness and porosity of the sea ice, scientists can estimate its age (generally one to 10 years). Microscopic organisms called diatoms in the ice provide clues to the ecosystem in the ocean below.....[ More ]

ANTARCTIC SEASCAPE:

The icebreaker Nathaniel B. Palmer plows a path through sea ice in the Prince Gustav Channel, just off the Antarctic Peninsula. Grounded by the dark bluffs of James Ross Island in the background, the scene is reminiscent of a sandy Utah desert—but the veneer of ice one meter thick conceals ocean water 700 to 1,000 meters deep.....[ More ]

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