Deuterium Excess in a Deep Greenland Ice Core: A proxy for Arctic Sea Ice Concentration

• Main Author: McGehee, Rebecca
• Format: Text
• Language: unknown
• Published: Carleton Digital Commons 2017
• Subjects: Deuterium excess; sea ice; Renland; ice core; climate change; linear regression; paleoclimate reconstruction; Arctic; Greenland; Climate change; Greenland ice core; Sea ice
• Online Access: https://digitalcommons.carleton.edu/comps/939

Rising ocean temperatures over the last several decades have led to an accelerated rate of sea ice decline in the northern latitudes. This study is motivated by a need to accurately model and predict sea ice dynamics in a rapidly changing climate. This study uses isotope data from the Renland ice core on the east coast of Greenland to identify the isotopic parameter deuterium excess (d-excess) as a proxy for Arctic sea ice concentration. A high d-excess signal is preserved during years with less sea ice, because a larger area of open ocean leads to increased local evaporation and kinetic fractionation of isotopes. A low d-excess signal is preserved during years with more sea ice, as a smaller area of open ocean decreases kinetic fractionation and shifts the origin of moisture towards the subtropics. Due to the strong influence that the origin of moisture has on the d-excess signal, I suggest using summer d-excess data to study changes in Arctic sea ice concentration. The greater variability seen in summer sea ice concentration leaves a stronger signal in the d-excess record and will make paleo-reconstructions more accurate. The identification of d-excess as a proxy for sea ice is the next step in constraining the spatial and temporal scale of abrupt climate change, and is vital to predicting the impact of anthropogenic climate change.