Ice Shelves Disappearing on the Antarctic PeninsulaGlacier Retreat and Sea-Level Rise Are Possible Consequences
Ice shelves are retreating in the southern section of the Antarctic Peninsula owing to climate change. Continued warming could result in glacier retreat and sea-level rise, threatening coastal communities and low-lying islands worldwide. The ice-shelf retreat is documented in a U.S. Geological Survey (USGS) report, "Coastal-Change and Glaciological Map of the Palmer Land Area, Antarctica: 1947-2009," released in late 2009.
Research by the USGS is the first to document that every ice front in the southern part of the Antarctic Peninsula has been retreating overall from 1947 to 2009, with the most dramatic changes occurring since 1990. The USGS previously documented that most of the ice fronts on the entire peninsula have also retreated during the late 20th century and into the early 21st century.
The ice shelves are attached to the continent and already floating, holding in place the Antarctic ice sheet that covers about 98 percent of the Antarctic continent. As the ice shelves break off, outlet glaciers and ice streams from the ice sheet can more easily flow into the sea. The transition of that ice from the land to the ocean is what raises sea level.
"This research is part of a larger ongoing USGS project that is for the first time studying the entire Antarctic coastline in detail, and this is important because the Antarctic ice sheet contains 91 percent of Earth's glacier ice," said the report's lead author, USGS scientist Jane Ferrigno. "The loss of ice shelves is evidence of the effects of global warming. We need to be continually on the alert to observe and evaluate, so that we may understand how and why our climate system is changing."
The peninsula is one of Antarctica's most rapidly changing areas because it is farthest from the extremely cold, main part of the Antarctic continent that surrounds the South Pole. The peninsula's ice-shelf loss may be a forecast of changes in other parts of Antarctica, and the world, if warming continues.
Retreat along the southern part of the peninsula is of particular interest because, in combination with earlier observations, it demonstrates that global warming is affecting the entire length of the peninsula.
The Antarctic Peninsula's southern section as described in this study contains five major ice shelves: Wilkins, George VI, Bach, Stange, and the southern part of the Larsen Ice Shelf. The ice lost since 1998 from the Wilkins Ice Shelf alone totals more than 4,000 km2, an area larger than the State of Rhode Island.
The USGS is working collaboratively on this project with the British Antarctic Survey, with the assistance of the Scott Polar Research Institute and Germany's Bundesamt für Kartographie und Geodäsie. The research is also part of the USGS Glacier Studies Project, which is monitoring and describing glacier extent and change over the whole planet by using satellite imagery.
The new report, "Coastal-Change and Glaciological Map of the Palmer Land Area, Antarctica: 1947-2009" (USGS Scientific Investigations Map 2600-C) and its accompanying map are available online at http://pubs.usgs.gov/imap/i-2600-c/.
A USGS report released in 2008 (USGS Scientific Investigations Map 2600-B) documented the complete disappearance of the Wordie Ice Shelf and the northern part of the Larsen Ice Shelf (see Sound Waves article, "New USGS Study Documents Rapid Disappearance of Antarctica's Ice Shelves").
The other completed reports in the Coastal-Change and Glaciological Maps of Antarctica series can be viewed at http://pubs.usgs.gov/imap/2600/.
Listen to a USGS CoreCast about this project at http://www.usgs.gov/corecast/details.asp?ep=121.
in this issue:
Ice Shelves Disappearing on the Antarctic Peninsula