Hostname: page-component-78c5997874-mlc7c Total loading time: 0 Render date: 2024-11-13T09:39:38.108Z Has data issue: false hasContentIssue false
  • English
  • Français

Effect of sea-level lowering on ELA depression during the LGM

Published online by Cambridge University Press:  20 January 2017

Brian Hanson  and
Roger LeB. Hooke
Brian Hanson*
Affiliation:
Department of Geography, University of Delaware, Newark, DE 19716, USA
Roger LeB. Hooke
Affiliation:
Department of Earth Sciences and Climate Change Institute, University of Maine, Orono, ME 04469, USA
*
⁎Corresponding author. Fax: +1 302 831 6654.
Get access Rights & Permissions [Opens in a new window]

Abstract

Decreases in equilibrium-line altitudes (ELAs) varied geographically during the last glacial maximum (LGM), with a mid-range value of ~ 900 m commonly deduced from altitude ratio and accumulation–area ratio calculations. Sea level, however, was 120 m lower during the LGM, so the ELA lowering relative to sea level would only be 780 m for a 900-m absolute lowering. With a lapse rate of 0.006°C m−1, this implies a 4.7°C lowering of global temperature. It has been argued that this correction for sea-level change is unnecessary, but the logic on which this is based requires adiabatic compression to apply over much longer time scales than is typically invoked. We find that the correction is necessary. In addition, geometric changes in the atmosphere during the LGM, pointed out by Osmaston (2006), could lead to 0.4°C decrease in the average temperature of the troposphere. Additionally, orographic effects could significantly change the snow distribution on mountain masses near sea level.

Keywords

Last glacial maximum (LGM)Equilibrium-line altitude (ELA)Adiabatic compressionSea-level depression
Type
Short Paper
Information
Quaternary Research , Volume 75 , Issue 3 , May 2011 , pp. 406 - 410
Copyright
University of Washington

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bolton, D. The computation of equivalent potential temperature. Monthly Weather Review 108, (1980). 1046–1053.2.0.CO;2>CrossRefGoogle Scholar
Broecker, W.C. Mountain glacier: recorders of atmospheric water vapor content?. Global Biogeochemical Cycles 11, 4 (1997). 589–597.CrossRefGoogle Scholar
CLIMAP Project Members The surface of the Ice-Age Earth. Science 191, (1976). 1131–1137.CrossRefGoogle Scholar
Gillespie, A., and Molnar, P. Asynchronous maximum advances of mountain and continental glaciers. Reviews of Geophysics 33, 3 (1995). 311–364.CrossRefGoogle Scholar
Greene, A.M., Seager, R., and Broecker, W.C. Tropical snow line depression at the last glacial maximum: comparison with proxy records using a single-cell tropical climate model. Journal of Geophysical Research 107, D8 (2002). 1029–2001.CrossRefGoogle Scholar
Guilderson, T.P., Fairbanks, R.G., and Rubenstone, J.L. Reconciling tropical sea surface temperature estimates for the last glacial maximum. Science 263, (1994). 663–665.CrossRefGoogle Scholar
Mark, B.G., Harrison, S.P., Spessa, A., New, M., Evans, D.J.A., and Helmens, K.F. Tropical snoline changes at the last glacial maximum: a global assessment. Quaternary International 138–139, (2005). 168–201.Google Scholar
Osmaston, H.A. Should Quaternary sea-level changes be used to correct glacier ELAs, vegetation belt altitudes and sea level temperatures for inferring climate change?. Quaternary Research 65, (2006). 244–251.CrossRefGoogle Scholar
Pigati, J.D., Zreda, M., Zweck, C., Almasi, P.F., Elmore, D., and Sharp, W.D. Ages and inferred causes of Late Pleistocene glaciations on Mauna Kea, Hawai'i. Journal of Quaternary Science 23, (2008). 683–702.CrossRefGoogle Scholar
Porter, S.C. Snowline depression in the tropics during the last glaciation. Quaternary Science Reviews 20, (2001). 1067–1091.CrossRefGoogle Scholar
Rostek, F., Ruhland, G., Bassinot, F.C., Müller, P.J., Labeyrie, L.D., Lancelot, Y., and Bard, E. Reconstructing sea surface temperature and salinity using 18O and alkenone records. Nature 364, (1993). 319–321.CrossRefGoogle Scholar
Roy, A.J., and Lachniet, M.S. Late Quaternary glaciation and equilibrium-line altitudes of the Mayan Ice Cap, Guatemala, Central America. Quaternary Research 74, (2010). 1–7.CrossRefGoogle Scholar
Salby, M. Fundamentals of Atmospheric Physics. International Geophysics Series Vol. 61, (1996). Academic Press, 627 pp.Google Scholar
Stansell, N.D., Polissar, P.J., and Abbott, M.B. Last glacial maximum equilibrium-line altitude and paleo-temperature reconstructions for the Cordillera de Mérida, Venezuelan Andes. Quaternary Research 67, (2007). 115–127.CrossRefGoogle Scholar
Wallace, J.M., and Hobbs, P.V. Atmospheric Science, an Introductory Survey. 2nd ed International Geophysics Series vol. 92, (2006). Academic Press, 483 pp.Google Scholar
Xu, X., Wang, L., and Yang, J. Last Glacial Maximum climate inferences from integrated reconstruction of glacier equilibrium-line altitude for the head of the Urumqi River, Tianshan Mountains. Quaternary International 218, (2010). 3–12.CrossRefGoogle Scholar