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Saturday, July 31, 2010

History of the Greenland Ice Sheet: Paleoclimatic insights, Quatern. Sci. Rev., 29 (July 2010), Richard B. Alley et al.

Quaternary Science Reviews, 29(15-16) pp. 1728-1756 (July 2010); doi:10.1016/j.quascirev.2010.02.007

History of the Greenland Ice Sheet: Paleoclimatic insights

Richard B. Alleya, Corresponding Author Contact Information, E-mail The Corresponding Author, J.T. Andrewsb, J. Brigham-Grettec, G.K.C. Clarked, K.M. Cuffeye, J.J. Fitzpatrickf, S. Funderg, S.J. Marshallh, G.H. Millerb, J.X. Mitrovicai, D.R. Muhsf, B.L. Otto-Bliesnerj, L. Polyakk and J.W.C. Whiteb


Paleoclimatic records show that the Greenland Ice Sheet consistently has lost mass in response to warming, and grown in response to cooling. Such changes have occurred even at times of slow or zero sea-level change, so changing sea level cannot have been the cause of at least some of the ice-sheet changes. In contrast, there are no documented major ice-sheet changes that occurred independent of temperature changes. Moreover, snowfall has increased when the climate warmed, but the ice sheet lost mass nonetheless; increased accumulation in the ice sheet's center has not been sufficient to counteract increased melting and flow near the edges. Most documented forcings and ice-sheet responses spanned periods of several thousand years, but limited data also show rapid response to rapid forcings. In particular, regions near the ice margin have responded within decades. However, major changes of central regions of the ice sheet are thought to require centuries to millennia. The paleoclimatic record does not yet strongly constrain how rapidly a major shrinkage or nearly complete loss of the ice sheet could occur. The evidence suggests nearly total ice-sheet loss may result from warming of more than a few degrees above mean 20th century values, but this threshold is poorly defined (perhaps as little as 2 °C or more than 7 °C). Paleoclimatic records are sufficiently sketchy that the ice sheet may have grown temporarily in response to warming, or changes may have been induced by factors other than temperature, without having been recorded.

Article Outline

1. The Greenland Ice Sheet
1.1. Overview
1.2. Ice-sheet behavior
2. Paleoclimatic indicators bearing on ice-sheet history

2.1. Marine indicators
2.2. Terrestrial indicators
2.2.1. Geomorphic indicators
2.2.2. Biological indicators and related features
2.2.3. Glacial-isostatic adjustment and relative sea-level indicators near the ice sheet
2.2.4. Far-field indicators of relative sea-level high-stands
2.2.5. Geodetic indicators
2.2.6. Ice cores
3. History of the Greenland Ice Sheet

3.1. Ice-sheet onset and early fluctuations
3.2. The most recent million years
3.2.1. Far-field sea-level indications
3.2.2. Ice-sheet indications
3.3. Marine isotope stage 5e

3.3.1. Far-field sea-level indications
3.3.2. Conditions in Greenland
3.3.3. Ice-sheet changes
3.4. Post-MIS 5e cooling to the Last Glacial Maximum (LGM, or MIS 2)

3.4.1. Climate forcing
3.4.2. Ice-sheet changes
3.5. Ice-Sheet retreat from the Last Glacial Maximum (MIS 2)

3.5.1. Climatic history and forcing
3.5.2. Ice-sheet changes
4. Discussion

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Link:   doi:10.1016/j.quascirev.2010.02.007

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