Changes in global ice volume from the time of the LGM to the present.
The figure shows ice-volume equivalent sea level for the past 20 kyr,
based on isostatically adjusted sea-level data from different localities.
(Lambeck et al., 2002) [1]
Climate changes in central Greenland over the last 17,000 years
show a large and rapid shift out of the ice age about 15,000
years ago, an irregular cooling into the Younger Dryas event,
and an abupt shift out of the event (a warming of about 8° C
in a decade) toward modern values (modified from Alley, 2000).
At the peak of the last Ice Age, Europe was almost uninhabitable to the north of the Alps and Pyrenees (Williams, 1998), but the Mediterranean basin had a fairly temperate climate and there was significant rainfall in North Africa. The Atlas mountains were covered by forests and the northern part of the Sahara by grasslands and savannas (Gasse, 2000). Elephants, lions and gazelles lived in the future desert (Prentice, 2000), whose landscape was not very different from today’s southern Europe.
Twenty thousand years ago the glacial to interglacial transition began and, over the next ten thousand years, the melting of glaciers raised the sea level of 120 meters, up to the present one (Lambeck, 2002). The rise of the sea level was not uniform, but characterized by sudden increases in temperature (Steffensen, 2008), among which two episodes were outstanding: the Melt Water Pulses (MWP) 1a and 1b (Wang, 2001). During the first MWP, about 14,500 years ago, the sea rose from -95 to -75 meters in just a few years, and then, 11,500 years ago, throughout the MWP-1b, from -58 to -43 meters (Liu, 2004).
The MWP-1a is often considered the indicator of the end of the Ice Age, because in the following millennium the temperatures were much higher and similar to the current ones. However, 13,000 years ago, the cold suddenly came back and for another 1,500 years, in the period known as the Younger Dryas (YD), the temperatures were again glacial (Alley, 2000). Also the Younger Dryas ended abruptly, with the MWP-1b, which marked the beginning of the Holocene.
Alley, R.B., The Younger Dryas cold interval as viewed from central Greenland. Quaternary Science Reviews 19 (2000), 213-226.
Gasse, F., Quat. Sci. Rev., 19, 2000.
Lambeck, K., T. M. Esat & E. K. Potter, Links between climate and sea levels for the past three million years. Nature, 419, 14 sept 2002, 199.
Liu, J. Paul, John D. Milliman, (2004) Reconsidering Melt-water Pulses 1A and 1B: Global Impacts of Rapid Sea-level Rise. Journal of Ocean University of China, Vol.3, No.2, pp.183-190.
Prentice, I. C., Jolly, D. and BIOME 6000 participants, 2000, Mid-Holocene and glacial-maximum vegetation geography of the northern continents and Africa, J. Biogeogr. 27, 507-519.
Steffensen, Jørgen Peder et al., High-Resolution Greenland Ice Core Data Show Abrupt Climate Change Happens in Few Years. Science 321, 680 (2008).
Wang, Y. J., H. Cheng, R. L. Edwards, Z.S. An, J. Y. Wu, C.-C. Shen, J. A. Dorale A High-Resolution Absolute-Dated Late Pleistocene Monsoon Record from Hulu Cave, China. Science Vol. 294, pp. 2345, 14 December 2001.
Williams, D. et al, Quaternary Environments (1998) Arnold, London.
Posted March 15, 2009, last modified October 17, 2011.
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