Talk by Sune O. Rasmussen, Centre for Ice and Climate – Niels Bohr Institute - University of Copenhagen

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Talk by Sune O. Rasmussen, Centre for Ice and Climate

Revising and extending the INTIMATE event stratigraphy: a proposal for how to count Greenland stadials and interstadials.

Since the very first ice core records showed the existence of alternating cold and warm periods during the last glacial, these variations have been assigned names and numbers to identify the oscillations and promote correlation and comparison between the ice core records and other types of sediment profiles. The most widely scheme, based on GRIP data in Dansgaard et al. (1993) used the terms stadials (cold) and interstadials (warm) and numbers assigned to the interstadials only. Björck et al. (1998) formalised the notation and numbering and added numbers to the stadials as part of the so-called INTIMATE event stratigraphy, which aimed at setting up a framework for robust correlation of climate records as part of the project INTegrating Ice core, MArine, and TErrestrial records. Subsequent updates and extensions by Walker et al. (1999), Lowe et al. (2008), and Blockley et al. (2012) sticked to this numbering strategy and defined start and end points of events down to and including interstadial 12. This scheme together with the numbering of deeper events as presented in NGRIP members (2004) is widely used although it is not the only scheme proposed (e.g., Rousseau et al., 2006).

With the increase in resolution of ice core records and the advent of a coherent dating framework for the Greenland ice cores, the Greenland Ice Core Chronology 2005 (GICC05), the current numbering scheme has become insufficient as Greenland climate is being analysed in several cores in parallel in still finer detail. The presentation will introduce a proposal on how to assign numbers to the interstadials and stadials that allow unique labelling of climate events also of shorter duration than what is included in the current numbering system, while maintaining the maximum degree of compatibility with the existing system.