Timing of the Little Ice Age in southern Greenland

Publikation: KonferencebidragPosterForskning

Dokumenter

Kurt H. Kjær, Kristian Kjellerup Kjeldsen, Anders Anker Bjørk, Shfaqat Abbas Khan, Niels Jákup Korsgaard, Svend Visby Funder, Nicolaj Krog Larsen, Bo Vinther, Camilla S. Andresen, Antony J. Long, Sarah A. Woodroffe, Eric Steen Hansen, Jesper Olsen

Northern hemisphere temperatures reached their Holocene minimum and most glaciers reached their maximum during The Little Ice Age (LIA), but the timing of specific cold intervals is site-specific. In southern Greenland, we have compiled data from organic matter incorporated in LIA sediments, used as a signal for ice-free terrain being overridden by LIA glacier advances, and data from threshold lakes showing the onset of glacier-fed lakes, thus revealing the advance-maximum phase initiating the LIA. Finally, we have compiled lichenometry results indicating the onset of bedrock vegetation succeeding ice retreat. Our results show that the advance of glaciers
during the LIA occurs early after the Medieval Warm Period terminating soon after 1200 AD and culminates c. 1500-1600 AD. Historical maps also show that many glaciers on the western coast occupy a still-stand near the LIA maximum until 1900 AD before retreat commence.

Thus in southern Greenland, we define LIA as the period between the first signs of Late Holocene glacier readvance and the latest onset of retreat – i.e. from ca. 1200 to c. 1900. During this period northern hemisphere annual mean temperatures, although fluctuating, were generally below the 1961-1990 average, with the coldest interval between c. 1600 and 1800. Even though winter temperatures may have dominated the cooling, also the summer temperatures which are most closely correlated with glacier mass balances, dropped, to c. 0.6 below the average in the northern hemisphere including the Arctic. Furthermore, the glacier response seems to be mirrored
by a oceanic cooling between 500-1000 AD, followed by onset of the LIA at 1150-1250 AD as seen in the relative strength of warm subsurface water and the influence of the East Greenland Current.
OriginalsprogEngelsk
Publikationsdato11 apr. 2013
Antal sider1
StatusUdgivet - 11 apr. 2013
BegivenhedEuropean Geosciences Union General Assembly 2013 - Vienna, Østrig
Varighed: 7 apr. 201312 maj 2013

Konference

KonferenceEuropean Geosciences Union General Assembly 2013
LandØstrig
ByVienna
Periode07/04/201312/05/2013

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