Recent Climate Change Feedbacks to Greenland Ice Sheet Mass Changes from GRACE

Fang Zou,Janet E Nichol,Robert Tenzer,Hok Sum Fok

doi:10.3390/rs12193250

Abstract

Although a significant effort has been dedicated to studying changes in the mass budget of the Greenland Ice Sheet (GrIS), mechanisms behind these changes are not yet fully understood. In this study, we address this issue by investigating the link between climate controls and mass changes of the GrIS between August 2002 and June 2017. We estimate the GrIS mass changes based on averaging the Gravity Recovery and Climate Experiment (GRACE) monthly gravity field solutions from four processing data centers. We then investigate the possible impact of different climate variables on the GrIS mass changes using the North Atlantic Oscillation (NAO), temperature, precipitation, and the 700 hPa wind retrieved from the ERA-5 reanalysis. Results indicate a decrease of −267.77 ± 32.67 Gt/yr in the total mass of the GrIS over the 16-year period. By quantifying the relationship between climate controls and mass changes, we observe that mass changes in different parts of Greenland have varying sensitivity to climate controls. The NAO mainly controls mass changes in west Greenland, where the summertime NAO modulations have a greater impact on the summer mass loss than the wintertime NAO modulations have on the winter mass gain. The GrIS mass changes are correlated spatially with summer temperature, especially in southwest Greenland. Mass balance changes in northwest Greenland are mostly affected by wind anomalies. These new findings based on wind anomalies indicate that the summer atmospheric circulation anomalies control surface temperature and snow precipitation and consequently affect mass changes in different parts of Greenland.

Highlights

The Greenland Ice Sheet (GrIS) (Figure 1) has been losing mass at a rate that is a major contribution to global sea-level rise in recent decades [1,2,3,4,5,6]
The summertime North Atlantic Oscillation (NAO) index has a greater impact on the summer mass loss than the wintertime NAO index on the winter mass gain
Our result shows that the GrIS total mass during the whole investigated period went through a rapid mass losing (2002–2008), followed by an accelerated mass loss (2009–2012), before a period of relatively slow mass loss (2013–2017)

Summary

Introduction

The Greenland Ice Sheet (GrIS) (Figure 1) has been losing mass at a rate that is a major contribution to global sea-level rise in recent decades [1,2,3,4,5,6]. The Gravity Recovery and Climate Experiment (GRACE) space mission in the terrestrial gravity field from space has been successfully used to monitor the mass changes in Greenland from temporal variations in space [20,21,22,23]. Previous studies used the SMB and ice discharge data for a detailed analysis and validation of GRACE results [12,23]. Zou et al (2020) [29] analyzed the temporal and spatial distribution of mass changes in Greenland over the past 15 years by using GRACE, SMB, and ice discharge data. The main purpose of this study is to investigate mechanisms behind mass changes when we used the GRACE mass change results in our analysis without separating the individual signals

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Discussion

Conclusion