Links between GRACE/GRACE-FO derived temporal mass variations in Greenland and climatic indices

The Greenland Ice Sheet (GIS) has been experiencing significant mass loss since the 1990s, driven by the intensifying effects of global warming. However, this global trend is modulated by distinct annual and interannual variations, highlighting the complex interplay between the ice sheet, atmospheric systems, and the ocean. In this study, we analyzed GIS mass changes from early 2002 to late 2023 using data from the GRACE and GRACE-FO missions, focusing on the dominant temporal cycles and their relationships with climatic indices and parameters.

Using Empirical Orthogonal Functions (EOF) applied to mass variation data from the COST-G solution, we identified five leading modes of variability, accounting for 67.5% of the total variance. The primary mode capture both the annual cycle and longer-term periodicities, while subsequent modes highlight interannual oscillations, with cycles ranging from 4 to 11 years.

We examined the interactions between GIS mass changes and six key climatic drivers: the North Atlantic Oscillation (NAO), Greenland Blocking Index (GBI), Atlantic Multidecadal Oscillation (AMO), temperature duration and intensity, precipitation, and surface albedo. Cumulative indices and parameters enabled direct comparisons with the accumulated mass changes since 2002. Through Wavelet Analysis and cross-correlations, we uncovered significant links with varying time lags. They lead to a complete annual cycle and some interannual relationship between them. For instance, a positive NAO phase enhances precipitation, while the AMO displays a surprising 3.5-year delayed response to mass variations.

Additionally, our findings reveal a connection between 11-year cycles in NAO, GBI, and temperature to solar activity, while 4 to 7-year cycles align with potential atmospheric oscillations and Earth’s internal geodynamics.

This study highlights the GIS as a dynamic system modulated by interrelated processes operating on annual to decadal timescales. We have only investigated Greenland in its globality, but we know that the response to external forcing at a scale of a basin or a glacier differs. It will be important to examine this point as the integrations of multi-scale climatic drivers is important to understand past variations and project future changes under a warming climate. Such understanding is vital for assessing global sea-level rise and formulating mitigation strategies.