We find that the melt event from 986 CE is most likely a large rain event similar to that from 2012 CE, and that these two events are unprecedented throughout the Holocene. In total, we can identify approximately 831 mm of melt (corrected for thinning) over the past 10 000 years. Our record of melt events shows a large, distinct peak around 1014 years b2k (986 CE) and a broad peak around 7000 years b2k, corresponding to the Holocene Climatic Optimum.
We analyze melt layer thicknesses, correct for ice thinning, and account for missing layers due to core breaks. We define the brittle zone in the EastGRIP ice core as that from 650 to 950 m depth, where we count on average more than three core breaks per meter. This transition is located at 1150 m depth in the EastGRIP ice core, corresponding to an age of 9720 years b2k. We detect and describe melt layers and lenses, seen as bubble-free layers and lenses, throughout the ice above the bubble–clathrate transition.
The data were acquired visually using an optical dark-field line scanner. We present a record of melt events obtained from the East Greenland Ice Core Project (EastGRIP) ice core in central northeastern Greenland, covering the largest part of the Holocene.
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