Macfee et al. (2025) Rising snowline altitudes across Southern Hemisphere glaciers from 2000 to 2023

Identification

• Journal: Scientific Reports
• Year: 2025
• Date: 2025-10-13
• Authors: Mia W. Macfee, Jonathan L. Carrivick, Duncan J. Quincey
• DOI: 10.1038/s41598-025-19486-6

Research Groups

• School of Geography and water@leeds, University of Leeds, Leeds, England.

Short Summary

This study determined the spatial patterns and temporal trends of end-of-summer snowline altitudes (SLAEOS) for 6364 glaciers across five Southern Hemisphere mountain regions from 2000 to 2023. It revealed a pervasive rise in SLAEOS on the majority of glaciers, with rates up to 7.18 meters per year, indicating widespread glacier mass loss, though some western regions experienced declines.

Objective

• To determine the spatial patterns and temporal trends of end-of-summer snowline altitudes (SLAEOS) for thousands of glaciers across the Southern Hemisphere from 2000 to 2023.

Study Configuration

• Spatial Scale: 6364 glaciers across five Southern Hemisphere mountain regions: Southern Alps of New Zealand, Antarctic Peninsula, Central Andes, Central Chilean Andes, and Southern Andes. These regions were further split into east and west morpho-climatic zones.
• Temporal Scale: 23 years, from 1 January 2000 to 31 December 2023.

Methodology and Data

• Models used:
  • Google Earth Engine (GEE) for satellite image retrieval, filtering, and analysis.
  • C Function of Mask (CFMask) algorithm for cloud masking.
  • SCS + C topographic correction method.
  • NIRSWIR Otsu method for binary snow/ice classification.
  • Linear regression for temporal trend identification.
  • t-test for statistical significance of trends.
• Data sources:
  • Landsat collections (Landsat 4 TM, 5 TM, 7 ETM+, 8 OLI) at 30 meters horizontal resolution.
  • ALOS AW3D30 v. 3.1 Digital Elevation Model (DEM) at 30 meters resolution (median date 2009).
  • Glacier outlines from Global Land Ice Measurements from Space (GLIMS) via the National Snow and Ice Data Center (NSIDC).
  • New Zealand aerial survey dataset and direct mass balance measurements from 6 reference glaciers for validation.

Main Results

• End-of-summer snowline altitudes (SLAEOS) increased on the majority of 6364 glaciers across the Southern Hemisphere between 2000 and 2023, with rates up to 7.18 meters per year.
• Anomalies from the multi-decadal mean SLAEOS became predominantly positive for all regions, especially between 2011 and 2023.
• The rate of SLAEOS rise accelerated by up to a factor of 4.0 in the western Southern Alps of New Zealand when comparing pre- and post-2010 rates of change.
• Region-wide median SLAEOS declined in the western Antarctic Peninsula (-0.28 ± 0.32 meters per year, statistically insignificant) and western Southern Andes (-0.98 ± 0.13 meters per year, statistically insignificant).
• The eastern Antarctic Peninsula showed the fastest rate of rise of any region at 6.39 ± 0.39 meters per year (p = 0.013).
• SLAEOS changes showed strong positive correlations with geodetic mass balance (r² = 0.76, increasing to 0.95 when excluding an anomalous glacier).
• The developed snow classification method achieved a mean accuracy of 87.4 ± 6.2%, with an absolute uncertainty of ± 18.7 meters for individual SLAEOS measurements.

Contributions

• Developed a novel Google Earth Engine-based approach for automated, large-scale retrieval and analysis of end-of-summer snowline altitudes (SLAEOS) for thousands of glaciers across multiple decades.
• Provided the first comprehensive quantification of spatial patterns and accelerating temporal trends of SLAEOS across the Southern Hemisphere from 2000 to 2023, addressing a significant research gap due to limited direct observations.
• Revealed pervasive glacier accumulation area reduction and increasingly negative mass balance across most Southern Hemisphere glaciers, with implications for committed ice loss and meltwater production.
• Identified complex spatio-temporal variability in SLAEOS trends, highlighting the interplay of temperature, precipitation, and large-scale climate modes (e.g., ENSO, SAM) across different regions.
• Established teleconnections between Andean and Southern Alps glaciers, showing in-phase behavior for northern Andes and out-of-phase for Patagonia.

Funding

• Natural Environment Research Council highlight topic grant Deplete and Retreat (NE/X004031/1).

Citation

@article{Macfee2025Rising,
  author = {Macfee, Mia W. and Carrivick, Jonathan L. and Quincey, Duncan J.},
  title = {Rising snowline altitudes across Southern Hemisphere glaciers from 2000 to 2023},
  journal = {Scientific Reports},
  year = {2025},
  doi = {10.1038/s41598-025-19486-6},
  url = {https://doi.org/10.1038/s41598-025-19486-6}
}