00_cover_Biennial Report 05-06.qxd - INSTAAR - University of ...

Rebecca Anderson (INSTAAR,left) and Gifford Miller(INSTAAR) collect a lake corefrom a lake on the northernplateau of Baffin Island, ArcticCanada, July 2005. The lake coreprovides information on the historyof ice cover on the plateauover the last several thousandyears. Photo: J. Briner (Universityof Buffalo).time, probably as seedlings or saplings, confirming thebelief of tribal members that “witness trees” were still presentat the site. The temporal and spatial patterns of treeestablishment are consistent with the prevailing flood-drivenmodel of cottonwood establishment in western NorthAmerica; the initiation dates of the three major age classescoincide with probable flood events on Big Sandy Creek.The completed study provides the Park Service and its tribalpartners with data critical to managing the cottonwood forestat Sand Creek as both a natural and cultural resource.The study was the subject of a feature article in theDaily Camera, a Boulder-based newspaper: “Witnesses toHorror—CU Researchers Study Sand Creek Cottonwoods”by Erika Engelhaupt (April 29, 2006).EARTH’S PAST SUGGESTS FUTUREPOLAR MELTING MAY RAISE SEALEVEL SOONER THAN EXPECTED.Gifford Miller was a member of two researchteams that combined paleoclimate evidencefrom the Last Interglacial period with climateand ice sheet modeling to infer that Earth’swarming temperatures are on track to melt the Greenlandand Antarctic ice sheets sooner than previously thoughtand ultimately lead to a global sea level rise of at least 20feet. If the current warming trends continue, by 2100 theEarth will likely be at least 4º Fahrenheit warmer than present,with the Arctic at least as warm as it was nearly130,000 years ago. At that time, significant portions of theGreenland and Antarctic Ice Sheets melted, resulting in asea level about 20 feet (6 meters) higher than present day.These studies are the first to link Arctic and Antarctic meltingduring the Last Interglaciation, 129,000 to 116,000 yearsago. The results were published in two adjacent papers inthe March 24, 2006, issue of Science.2005ALASKA’S COLUMBIA GLACIERRETREATING RAPIDLY. Tad Pfeffer(INSTAAR and CEAE) leads a researchgroup that has documented the rapid tidewaterretreat of the Columbia Glacier inAlaska, one of the fastest moving glaciersin the world. Since the early 1980s,Columbia Glacier has retreated 9 miles from its originalendpoint in the Pacific Ocean at Prince William Sound, andhas reached flow speeds as high as 88 feet per day. The glacieris the largest single contributor to sea level rise amongall North American glaciers, and accounts for about 10% oftotal glacial discharge from the Alaska/Yukon region eachyear.The retreat of Columbia Glacier is part of a cyclic patternof slow advance and abrupt retreat typical of Alaskan tidewater(or ocean-terminating) glaciers, according to Pfeffer.The abrupt retreat was probably triggered by long-term meltand thinning, occurring over the past century or so for theColumbia Glacier, he added. The retreat of Columbia Glacieris being used as a model for apparently similar retreats nowbeginning on the outlet glaciers of southern Greenland. Anadditional question, Pfeffer said, is whether the same conditionscausing the worldwide shrinkage of land-terminatingglaciers will alter the cyclic pattern of tidewater glaciers, andprevent readvance, either in Alaska or Greenland. Since theretreat of Columbia Glacier began in the 1980s, the glacierhas thinned up to 1300 feet in places, and is increasinglyinfluenced by the upward pressure of underlying seawateron the part of the glacier that extends into the ocean.Pfeffer estimates that the tidewater glacier is about halfwaythrough its projected retreat. The glacier is predicted to fallback another 9 miles over the next 20–25 years and thenstabilize with its terminus near sea level.Pfeffer and doctoral student Shad O’Neel have beenworking with other researchers to monitor the glacier usingaerial photography, time-lapse photography, seismometers,and other instruments. Both Pfeffer and O’Neel presentedthe group’s latest results at the American GeophysicalUnion national conference in December.METHANE GYRATIONS IN PAST2000 YEARS SHOW HUMANINFLUENCE ON ATMOSPHERE.Dominic Ferretti, Jim White, and colleaguesfrom the U.S., New Zealand, and Australiaused pioneering stable isotopic techniqueson air samples extracted from the tiny bubblestrapped in Antarctic ice cores to show that methane,a potent greenhouse gas in Earth’s atmosphere, has been10 | RESEARCH MISSION