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Meeting of the minds

West Antarctic puzzles bring together polar researchers at annual workshop

 

The West Antarctic Ice Sheet (WAIS) Initiative focuses on two key questions: How will the West Antarctic ice sheet affect future sea level? And how do rapid global climate changes occur?

At the 18th annual WAIS Initiative workshop, held near Loveland, Colo., last month, it was apparent those questions are still at the forefront, but new technologies and techniques are bringing scientists ever closer to understanding Antarctica’s complex ice dynamics and its role in the global climate system.

Ted Scambos noted that researchers must embrace a wide variety of disciplines to understand the interaction between the ice, ocean and atmosphere — three processes involved in a complex dance that’s warming much of West Antarctica and causing glaciers to flow faster to the sea, which ultimately raises sea level.

“We still want to further underscore the value of multidisciplinary research into the West Antarctic Ice Sheet. It’s clear that things like atmosphere-ice and ocean-ice interactions are going to be key to understanding how it’s changed in the past, how it’s changing in the present, and what’s going to happen in the future,” said Scambos, lead scientist at Boulder’s National Snow and Ice Data Center (NSIDC).

NSIDC hosted this year’s meeting, attended by nearly 100 glaciologists, geologists, meteorologists and other others, including many early-career scientists. The workshop, partly supported by the National Science Foundation’s Office of Polar Programs (OPP), involved about 2½ days of presentations and discussions, ranging from the latest observations made from satellites and aircraft to some of the upcoming expeditions to Antarctica.

Several of the presentations ranged well outside the Antarctic, spanning the globe to Greenland, which is also undergoing dramatic changes, to places where one wouldn’t think to go in a meeting dedicated to ice and snow.

“The tropics are a bigger player than we thought,” said Ryan Fogt, an assistant professor of meteorology at Ohio University, who was one of the workshop’s keynote speakers.

Fogt has a grant from NSF to understand the warming under way in West Antarctica and the Antarctic Peninsula, and the associated loss of sea ice, from a meteorological point of view. He believes a persistent low-pressure system, influenced by large-scale climate modes like the El-Niño Southern Oscillation (ENSO), plays a role because it helps sustain the circulation pattern that leads to warming in the region.

“[The Antarctic is] connected to the rest of the globe,” observed Eric Steig, a professor at the University of Washington in Seattle, whose presentation also focused on influences to West Antarctica from the tropical Pacific Ocean. Not only does the Antarctic react to changes farther north, but it “pays it forward” in changes to sea level and ocean circulation, according to Steig.

His research with colleagues, published earlier this year in the journal Nature, suggests that rising sea surface temperatures in the area of the Pacific Ocean along the equator and near the International Date Line drive atmospheric circulation that has caused some of the largest shifts in Antarctic climate in recent decades.

There were the usual debates played out among such presentations: What exactly is causing the changes in the atmosphere above Antarctica that is strengthening westerly winds, which are drawing relatively warm circumpolar deep water (CDW) onto the continental shelf? Is it influenced by the tropics or ozone depletion in the stratosphere? Most everyone agrees that the CDW is responsible for weakening the ice shelves that hold back the glaciers from below.

NASA scientist Robert Bindschadler and his field team will begin taking a look at that process this upcoming season in West Antarctica. The researchers will land by helicopter on the Pine Island Glacier Ice Shelf where they’ll melt a hole 600 meters deep through the ice before deploying instruments into the ocean cavity below. They hope to get data on what’s happening between the ice and water.

“The objective still is quantifying the contributions to sea level from the West Antarctic Ice Sheet,” Bindschadler said during a discussion about the WAIS Initiative’s research priorities looking forward to the future.

Another major NSF-funded project tackling ice sheet dynamics is WISSARD, for Whillans Ice Stream Subglacial Access Research Drilling. A multiyear, multidisciplinary program, WISSARD will explore the subglacial lake system that exists at the boundary between West Antarctica and the Ross Ice Shelf.

Members of the WISSARD team presented some of the findings from recent fieldwork to map one of the key sites in their investigation, subglacial Lake Whillans, with radars and seismic imaging. In coming years, researchers will use a hotwater drill to access the lake and other parts of the subglacial waterworks, sending robots and instruments into the ice-covered environment to learn more about its mysteries and the role it plays in ice sheet dynamics.

Few among the group would dispute that future research in West Antarctica and elsewhere will increasingly rely on remote sensing — instruments aboard satellites or aircraft that can provide various details about the ice regarding its thickness, layers and even motion.

Bernd Scheuchl, an associate project scientist at the University of California-Irvine’s Department of Earth System Science, presented work done by Eric Rignot’s research group that created a digital mosaic of ice motion covering all of Antarctica.

Using satellite data from the Japanese, Canadian and Europeans, the NASA-funded, color-coded map shows where ice drains from the interior to the exterior of the continent. The colors represent the speed of the ice, making the animated map that Scheuchl presented look like thick-trunked trees (where the glaciers flow to the sea or terminate at ice shelves), with bristling branches (where small rivers of ice begin to stream from the interior).

Recent air campaigns above Antarctica are also changing the way scientists see the continent.

A project called ICECAP, for Investigating the Cryospheric Evolution of the Central Antarctic Plate, created a new topographical map of the bedrock below the East Antarctic Ice Sheet that revealed some of the largest fjords, or ice-cut channels, on Earth.

For three field seasons, the research team flew an upgraded World War II-era DC-3 aircraft with a suite of geophysical instruments to study the ice and underlying rock below Antarctica’s larger ice sheet. The findings from the project, partly funded by NSF, should provide important insight into the history of ice in Antarctica, as well as improve computer models of how the ice sheet might behave in the future as the climate changes.

“We are moving into a different world,” noted Duncan Young, a research scientist at The University of Texas at Austin’s Institute for Geophysics who presented the ICECAP data at the workshop, referring to the recent discoveries about Antarctica that are changing how scientists understand its ice dynamics.

ICECAP will continue mapping East Antarctica’s ice for another two field seasons, as part of the NASA initiative called Operation IceBridge. The six-year program, spanning both Antarctica and Greenland, began its third campaign in the Antarctic this month. The goal of IceBridge is to bridge the gap between the data provided by a satellite called ICESat-1, which stopped operating in 2009, and the launch of its successor, ICESat-2, in 2016.

The 2011 Antarctic IceBridge campaign will feature the return of NASA’s DC-8, the agency’s largest plane in its airborne research fleet. This year’s program will also include for the first time the Gulfstream V (G-V), which is operated by the NSF and National Center for Atmospheric Research (NCAR). ICECAP’s modified DC-3 will fly across parts of East Antarctica where the other two planes can’t reach from their base of operations in Punta Arenas, Chile.

“The areas where we go and collect data are pretty much defined by where changes are happening, where we see changes happening in satellite missions,” said Michael Studinger, project scientist at NASA Goddard Space Flight Center.

That seems to be the mantra the workshop scientists have adopted — go where the changes are happening. The question of how Antarctica will respond in a changing world will take them to crevassed ice shelves and ice-choked seas. It will require innovative technologies aboard aircraft or robots sent to explore subglacial seas.

“The question is larger than any one investigator,” Bindschadler said.

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Curator: Peter Rejcek, Antarctic Support Contract | NSF Official: Winifred Reuning, Division of Polar Programs