20 March - 20 May 2019
Punta Arenas, Chile to Punta Arenas, Chile
Michael Weber & Maureen Raymo
Trevor Williams
Lee Stevens and Marlo Garnsworthy
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IODP Report

Iceberg Alley and Subantarctic Ice and Ocean Dynamics

 

A large tabular iceberg floating on the Southern Ocean, Antarctica, at sunrise
Large tabular iceberg, Antarctica                                                                                                                                Credit: Marlo Garnsworthy

Polar researchers predict that global sea level will rise about one meter (around 3.2 feet) by 2100. Much of this rise will be due to melting of the Antarctic Ice Sheet, the massive layer of ice, on average 1.3 miles thick, that covers the vast continent of Antarctica. But how much will sea level rise and how fast?

Icebergs break, or “calve,” off the edges or margins of the Antarctic Ice Sheet. Most travel counterclockwise around the Antarctic coast and converge in the Weddell Sea. From here, they drift northward through “Iceberg Alley” into the warmer waters of the Antarctic Circumpolar Current, which races clockwise around Antarctica.

As icebergs melt in these warmer waters, the dust, dirt, and rocks they carry—known as “iceberg rafted debris”—fall down through the ocean and are deposited as sediment on the seafloor. The JOIDES Resolution can drill hundreds of meters into this sediment and retrieve long cylinders of mud called cores. These sediment cores will provide a nearly continuous history of changes in melting of the Antarctic Ice Sheet.

Diagram showing drill sites in the Drake Passage near the Antarctic Peninsula, as well as an insert map of Antarctica showing a counter clockwise circulation of icebergs around the continent.
Figure modified from Weber et al. (2014).

Analyzing the iceberg rafted debris can tell us when the ice sheet calved icebergs and even which part of Antarctica they came from. At times when more debris was deposited, we know the ice sheet was less stable. Much shorter cores previously collected at our drilling sites reveal high sedimentation rates, allowing us to observe climatic and ice sheet changes on timescales ranging from just tens to hundreds of years.

Scientists have discovered that episodes of massive iceberg discharge can happen abruptly, within decades. This has huge implications for how the Antarctic Ice Sheet may behave in the future.

We will also explore how ocean currents, sea ice, and atmospheric conditions in the past are related to changes in melting of the Antarctic Ice Sheet. As we collect cores to the north and the south of the Drake Passage, the narrow waters between Antarctica and the tip of South America, we will be able to see how the Antarctic Circumpolar Current has changed over time. Our northern drilling sites will additionally tell us about another historically important ice sheet: the Patagonia Ice Sheet.

Together, all of this data will illustrate the long-term climate history of Antarctica, showing how the ice sheets responded to changes in atmospheric carbon dioxide in the past, and how changes in the ice sheet influenced global sea level. This knowledge will help us understand how the Antarctic Ice Sheet may respond in a warming world, better preparing us for future global sea level rise.

 

 

 

ExP382 Iceberg Alley in the Media

BBC News: Climate Change and Drilling in ‘Iceberg Alley’

National Science Foundation: Scientists Set Sail on Expedition to Investigate Iceberg Alley Off Antarctica

European Geosciences Union:  EGU Cryosphere

ConCiencia, Andalucía Televisión, inclu. interview with Marga Garcia.

Envirobites: Voyage to Iceberg Alley

Physics.org: Deep-sea Drillers Investigate Shedding of Antarctic Icebergs

State of the Planet, Columbia University: Deep-sea Frillers Investigate Shedding of Antarctic Icebergs

Universität Bonn: Wettertechnisch so ziemlich am schlimmsten Ort der Erde

Die RheinPfalz: Aus Glan-Münchweiler in die Antarktis: Michael Weber ist Leiter einer bedeutenden Expedition

BLOGS BY OUR SCIENTISTS

PlanetErde: Week 1: Warten im Labyrinth  By Thomas Ronge

PlanetErde: Week 2: Klimageschichte im Schlamm By Thomas Ronge

PlanetErde: Week 3: Auf den Spuren von winzigen Meeresbewohnern By Linda Armbrecht

PlanetErde: Week 4: Shades of Gley by Anna Glüder

Expedition Antarctica: IODP Expedition 382 Week 1: Our foray into Iceberg Alley and Subantarctic Ice and Ocean Dynamics By Michelle Guitard

Expedition Antarctica: IODP Expedition 382 Week 2: Our First Cores & the Chaos That Ensued By Michelle Guitard

Expedition Antarctica: IODP Exp. 382 Week 4: Our best-laid plans

Expedition Iceberg Alley By Frida S. Hoem

 

Ice shelf towering above dark, calm water
Ice shelf, Weddell Sea [Credit: Mike Weber]
A blue iceberg. split down the middle, against a cloud sky
Broken iceberg [Credit: Mike Weber]
 

 

 

 

 

 

Author:
Lee Stevens
About:
I am an Education and Outreach Officer for Expedition 382 to Iceberg Alley. I also create videos and animations for the American Museum of Natural History.
More articles by: Lee Stevens