Temperature reconstruction from 10 to 120 kyr b2k from the NGRIP ice core
In order to reconstruct the temperature of the North Greenland Ice Core Project (NGRIP) site, new measurements of δ<sup>15</sup>N have been performed covering the time period from the beginning of the Holocene to Dansgaard–Oeschger (DO) event 8. Together with previously measured and most...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-04-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/10/887/2014/cp-10-887-2014.pdf |
| Summary: | In order to reconstruct the temperature of the North Greenland Ice Core
Project (NGRIP) site, new measurements of δ<sup>15</sup>N have been performed
covering the time period from the beginning of the Holocene to
Dansgaard–Oeschger (DO) event 8. Together with previously measured and
mostly published δ<sup>15</sup>N data, we present for the first time a NGRIP
temperature reconstruction for the whole last glacial period from 10 to
120 kyr b2k (thousand years before 2000 AD) including every DO event based
on δ<sup>15</sup>N isotope measurements combined with a firn densification and
heat diffusion model. The detected temperature rises at the onset of DO
events range from 5 °C (DO 25) up to 16.5 °C (DO 11) with an
uncertainty of ±3 °C. To bring measured and modelled data into
agreement, we had to reduce the accumulation rate given by the NGRIP
ss09sea06bm timescale in some periods by 30 to 35%, especially during the
last glacial maximum. A comparison between reconstructed temperature and
δ<sup>18</sup>O<sub>ice</sub> data confirms that the isotopic composition of
the stadial was strongly influenced by seasonality. We evidence
an anticorrelation between the variations of the
δ<sup>18</sup>O<sub>ice</sub> sensitivity to temperature (referred to as
α) and obliquity in agreement with a simple Rayleigh distillation
model. Finally, we suggest that α might be influenced by the Northern
Hemisphere ice sheet volume. |
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| ISSN: | 1814-9324 1814-9332 |