| The Greenland ice core from NorthGRIP (NGRIP) contains a proxy climate record
across the Pleistocene–Holocene boundary of unprecedented clarity and resolution.
Analysis of an array of physical and chemical parameters within the ice enables the
base of the Holocene, as reflected in the first signs of climatic warming at the end
of the Younger Dryas/Greenland Stadial 1 cold phase, to be located with a high
degree of precision. This climatic event is most clearly reflected in an abrupt shift
in deuterium excess values, accompanied by more gradual changes in δ18O, dust
concentration, a range of chemical species, and annual layer thickness. A timescale based on
multi-parameter annual layer counting provides an age of 11,700 calendar yr b2k (before AD
2000) for the base of the Holocene, with a maximum counting error of 99 yr. A
proposal that an archived core from this unique sequence should constitute the Global
Stratotype Section and Point (GSSP) for the base of the Holocene Series/Epoch
(Quaternary System/Period) has been ratified by the International Union of Geological
Sciences.
The results have been published in Journal of Quaternary Science vol. 24(1), pp. 3–17,
2009 by an author team consisting of Mike Walker, Sigfus Johnsen, Sune Olander
Rasmussen, Trevor Popp, Jørgen-Peder Steffensen, Phil Gibbard, Wim Hoek, John Lowe,
John Andrews, Svante Björck, Les C. Cwynar, Konrad Hughen, Peter Kershaw,
Bernd Kromer, Thomas Litt, David J. Lowe, Takeshi Nakagawa, Rewi Newnham,
and Jakob Schwander. The poster presents the definition and the underlying data. |