Long-term Studies of Tidewater and Terrestrial Dynamics, Glacier Hydrology, and Holocene and Historic Climate Activity; Glacier Bay, Southeast Alaska

Understanding tidewater and terrestrial glacier processes is critical when determining the impacts that contemporary climate and anthropogenic influences play in long-term glacier response. This understanding can only be acquired through a myriad of long-term glaciological and environmental measurements aimed to quantify glacial system response. The primary focus of our long-term investigations in Glacier Bay, Southeast Alaska is to better understand regional and global factors, such as climate, hydrology, oceanography and geophysical processes that control terrestrial and marine based physical systems. Our recent climatic investigations include analyzing modern climate trends at 26 locations across Glacier Bay and measuring the isotopic composition (oxygen and hydrogen) of precipitation, surface water, and glacier ice to assess regional hydrologic trends. Stable isotopes from samples of glacier ice, precipitation, and meteoric waters, have provided a regional assessment of the hydrologic cycle and weather patterns, allowing us to examine how current climate affects glacier activity and mass balance, and to assess the effect of precipitation on subglacial processes. Concurrently, the Park's longer-term Holocene glacial history and paleoclimate are being investigated using dendrochronological and radiocarbon dating of in-situ stumps, logs and soils. We have precisely located samples of ~100 interstadial stumps believed to be overridden as ice moved down-fjord during glacial periods, as well as over 100 paleo-wood samples found in adjacent moraine, outwash, and lacustrine sediment deposits. Conventional radiocarbon dating by Accelerated Mass Spectrometry (AMS) has provided an estimate of ice-marginal positions throughout the Holocene. Using these data, we are also attempting to develop a tree-ring chronology of the last 9,000 years. If we succeed, this would be a unique dendrochronological record for a subarctic region in North America.