Varying regional δ18O–temperature relationship in high-resolution stable water isotopes from east Greenland

• Published in: Climate of the Past
• Main Authors: Holme, Christian, Gkinis, Vasileios, Lanzky, Mika, Morris, Valerie, Olesen, Martin, Thayer, Abigail, Vaughn, Bruce H., Vinther, Bo M.
• Format: Other/Unknown Material
• Language: English
• Published: 2019
• Subjects: envir; geo; Greenland; Renland; East Greenland; Fram Strait; ice core; Iceland; North Atlantic; North Atlantic oscillation; Sea ice
• Online Access: https://doi.org/10.5194/cp-15-893-2019; https://cp.copernicus.org/articles/15/893/2019/

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 ...