Varying regional <i>δ</i><sup>18</sup>O–temperature relationship in high-resolution stable water isotopes from east Greenland
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Published:2019-05-16
Issue:3
Volume:15
Page:893-912
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ISSN:1814-9332
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Container-title:Climate of the Past
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language:en
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Short-container-title:Clim. Past
Author:
Holme ChristianORCID, Gkinis VasileiosORCID, Lanzky MikaORCID, Morris ValerieORCID, Olesen Martin, Thayer AbigailORCID, Vaughn Bruce H.ORCID, Vinther Bo M.
Abstract
Abstract. This study examines the stable water isotope signal
(δ18O) of three ice cores drilled on the Renland peninsula
(east Greenland coast). While ice core δ18O measurements
qualitatively are a measure of the local temperature history, the
δ18O variability in precipitation actually reflects the
integrated hydrological activity that the deposited ice experienced from the
evaporation source to the condensation site. Thus, as Renland is located next
to fluctuating sea ice cover, the transfer function used to infer past
temperatures from the δ18O variability is potentially
influenced by variations in the local moisture conditions. The objective of
this study is therefore to evaluate the δ18O variability
of ice cores drilled on Renland and examine the amount of the signal that
can be attributed to regional temperature variations. In the analysis, three
ice cores are utilized to create stacked summer, winter and annually averaged
δ18O signals (1801–2014 CE). The imprint of temperature on
δ18O is first examined by correlating the
δ18O stacks with instrumental temperature records from
east Greenland (1895–2014 CE) and Iceland (1830–2014 CE) and with the
regional climate model HIRHAM5 (1980–2014 CE). The results show that the
δ18O variability correlates with regional temperatures on
both a seasonal and an annual scale between 1910 and 2014, while
δ18O is uncorrelated with Iceland temperatures between
1830 and 1909. Our analysis indicates that the unstable regional
δ18O–temperature correlation does not result from changes
in weather patterns through strengthening and weakening of the
North Atlantic Oscillation. Instead, the results imply that the varying
δ18O–temperature relation is connected with the volume
flux of sea ice exported through Fram Strait (and south along the coast of
east Greenland). Notably, the δ18O variability only
reflects the variations in regional temperature when the temperature anomaly
is positive and the sea ice export anomaly is negative. It is hypothesized
that this could be caused by a larger sea ice volume flux during cold years
which suppresses the Iceland temperature signature in the Renland
δ18O signal. However, more isotope-enabled modeling
studies with emphasis on coastal ice caps are needed in order to quantify the
mechanisms behind this observation. As the amount of Renland
δ18O variability that reflects regional temperature varies
with time, the results have implications for studies performing
regression-based δ18O–temperature reconstructions based on
ice cores drilled in the vicinity of a fluctuating sea ice cover.
Funder
FP7 Ideas: European Research Council
Publisher
Copernicus GmbH
Subject
Paleontology,Stratigraphy,Global and Planetary Change
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