HR: 1340h
AN: PP43A-0997    [Abstracts]
TI: North American Moisture Gradients over the Past 15,000 Years Recorded by Lake Levels
AU: * Henderson, A
EM: ahenderson@gmail.com
AF: Limnological Research Center, Department of Geology and Geophysics, University of Minnesota, 500 Pillsbury Drive SE, Minneapolis, MN 55455, United States
AU: Plank, C
EM: plan0093@umn.edu
AF: Limnological Research Center, Department of Geology and Geophysics, University of Minnesota, 500 Pillsbury Drive SE, Minneapolis, MN 55455, United States
AU: Shuman, B N
EM: bshuman@uwyo.edu
AF: Department of Geology and Geophysics, University of Wyoming, 1000 University Avenue, Laramie, WY 82071, United States
AB: Spatial variation in the water levels of lakes provides a useful record of past moisture regimes and their associated synoptic climate patterns. Here, we present updated maps of North American lake levels over the past 15,000 years. Data have been assembled from published lake records in all regions of the continent, and focus on records that provide direct evidence of past shoreline elevations. The results show both the effects of short- term climate variability and the sensitivity of moisture gradients to the boundary conditions of the global climate system. For example, some lakes like Hidden Lake, Colorado, record the infrequent decadal-to-centennial "megadroughts" of the past two millennia that have been captured in tree-ring data, and nearly all lakes in the Rockies and Great Plains record persistently dry conditions for multiple millennia between 8000 and 5000 years BP. Regional climate model simulations show that the documented long-term aridity may have resulted from the direct effects of orbitally-driven changes in seasonal insolation patterns. Consequently, although "megadroughts" may be part of the natural moisture regimes of the late-Holocene, large magnitude shifts in boundary conditions both in the past (e.g., insolation) and future (i.e., greenhouse gases) have the potential to fundamentally alter the availability of water.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1637 Regional climate change
DE: 1812 Drought
DE: 1833 Hydroclimatology
DE: 1836 Hydrological cycles and budgets (1218, 1655)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting