Sims, David

English

UNH Scholars' Repository

University of New HampshireUniversity of New Hampshire Scholars' RepositoryMedia Relations Administrative Offices12-1-2004UNH Scientist Co Authors Report In NatureShowing Movement Of Glacier Has DoubledSpeedDavid SimsFollow this and additional works at: https://scholars.unh.edu/newsThis News Article is brought to you for free and open access by the Administrative Offices at University of New Hampshire Scholars' Repository. It hasbeen accepted for inclusion in Media Relations by an authorized administrator of University of New Hampshire Scholars' Repository. For moreinformation, please contact nicole.hentz@unh.edu.Recommended CitationSims, David, "UNH Scientist Co Authors Report In Nature Showing Movement Of Glacier Has Doubled Speed" (2004). UNH Today.1806.https://scholars.unh.edu/news/180610/9/17, 11(13 AMUNH Scientist Co-Authors Report In Nature Showing Movement Of Glacier Has Doubled SpeedPage 1 of 2http://www.unh.edu/delete/news/news_releases/2004/december/ds_120104glacier.htmlRelated LinksUNH Institute for theStudy of Earth,Oceans, and Space NOAA UNH Scientist Co-Authors Report In Nature ShowingMovement Of Glacier Has Doubled SpeedContact: David Sims603-862-5369 Science WriterInstitute for the Study of Earth, Oceans, and SpaceGretchen Cook-AndersonHeadquarters, Washington (202) 358-0836Krishna RamanujanGoddard Space Flight Center, Greenbelt, Md.(607) 273-2561 Dec. 1, 2004DURHAM, N.H. -- The world’s fastest glacier, Greenland's Jakobshavn Isbrae, doubled its speedbetween 1997 and 2003. The rapid movement of ice from land into the sea provides keyevidence of newly discovered relationships between ice sheets, sea level rise and climatewarming.The findings were reported in the journal Nature on Dec. 2, 2004. Co-authoring the study wasUniversity of New Hampshire glaciologist Mark Fahnestock of the Institute for the Study ofEarth, Oceans, and Space (EOS).The researchers found the glacier’s sudden speed-up also coincides with very rapid thinning,indicating loss of ice of up to 15 meters (16.4 yards) in thickness per year after 1997. Along withincreased rates of ice flow and thinning, the floating ice that extends from the mouth of theglacier into the ocean, called the ice tongue, began retreating in 2000, breaking up almostcompletely by May 2003. The authors began looking at the flow of this glacier using satellite pictures after pronouncedthinning was measured by a NASA aircraft. The satellite imagery revealed the dramaticacceleration. Fahnestock found this signal to be quite striking.“This speedup is the most dramatic change observed in a large glacier to date”, Fahnestock said.“Observing a doubling of the flow of one of the large rivers of ice draining the Greenland IceSheet in such a short time raises questions about the nature and stability of the ice sheet,” The NASA-funded study relies on data from satellites and airborne lasers to derive icemovements. The study’s lead author, Ian Joughin, conducted much of this research whileworking at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Joughin is currently a10/9/17, 11(13 AMUNH Scientist Co-Authors Report In Nature Showing Movement Of Glacier Has Doubled SpeedPage 2 of 2http://www.unh.edu/delete/news/news_releases/2004/december/ds_120104glacier.htmlglaciologist at the Applied Physics Laboratory at the University of Washington, Seattle. Co-authors include Waleed Abdalati, a senior scientist at NASA’s Goddard Space Flight Center,Greenbelt, Md., and Fahnestock.“In many climate models glaciers are treated as responding slowly to climate change,” Joughinsaid. “In this study we are seeing a doubling of output beyond what most models would predict.The ice sheets can respond rather dramatically and quickly to climate changes.” “This finding suggests the potential for more substantial thinning in other glaciers in Greenland,”Abdalati added. “Other glaciers have thinned by over a meter a year, which we believe is toomuch to be attributed to melting alone. We think there is a dynamic effect where the glaciers areaccelerating as warming causes conditions to change at the boundaries of these ice streams.” The researchers used satellite and other data to observe large changes in both speeds andthickness between 1985 and 2003. The data showed that the glacier slowed down from a velocityof 6700 meters (4.2miles) per year in 1985 to 5700 meters (3.5 miles) per year in 1992. Thislatter speed remained somewhat constant until 1997. By 2000, the glacier had sped up to 9400meters (5.8 miles) per year, topping out with the last measurement in spring 2003 at 12,600meters (7.7miles) per year. Airborne laser altimetry measurements of Jakobshavn’s surface elevation, made previously byresearchers at NASA’s Wallops Flight Facility, showed a thickening or building up of the glacierfrom 1991 to 1997, coinciding closely with the glacier’s slow-down. Similarly, the glacier beganthinning by as much as 15 meters (16.4 yards) a year just as its velocity began to increasebetween 1997 and 2003. The authors used synthetic aperture radar (SAR) data from Canada’s RADARSAT and theEuropean Space Agency’s European Remote Sensing Satellites to measure the glacier's velocityin 1992, 1994, 1995 and 2000. They also tracked distinct features in NASA Landsat image pairsto determine velocities in 2001, 2002 and 2003. Speeds from 1997 were determined usingairborne laser survey data. Researchers at the University of Maine and Ohio State Universityused airborne photographs to calculate historical 1985 velocities.The acceleration comes at a time when the floating ice near the glacier’s calving front has shownsome unusual behavior. Despite its relative stability from the 1950s through the 1990s, theglacier’s ice tongue began to break apart in 2000, leading to almost complete disintegration in2003. The tongue’s thinning and break up likely reduced its restraining effects on the ice behindit, as several speed increases coincided with losses of sections of the ice tongue as it broke up.Recent NASA-funded research in the Antarctic Peninsula showed similar increases in glacierflow following the Larson B ice shelf break-up. Jakobshavn Isbrae is Greenland’s largest outlet glacier, draining 6.5 percent of Greenland’s icesheet area. The ice stream’s speed-up and near-doubling of ice flow from land into the ocean isimportant because this one glacier has increased the rate of sea level rise by about .06millimeters per year, or roughly 4 percent of the 20th century rate of sea level increase. Mark Fahnestock can be reached at (603) 862-5065 or mark.fahnestock@unh.edu.

UNH Scientist Co Authors Report In Nature Showing Movement Of Glacier Has Doubled Speed

https://scholars.unh.edu/cgi/viewcontent.cgi?article=2809&amp;context=news

UNH Scientist Co Authors Report In Nature Showing Movement Of Glacier Has Doubled Speed

Abstract

Similar works

Full text

Available Versions

UNH Scholars' Repository