- 1School of Environmental Sciences, University of Liverpool (j.lea@liverpool.ac.uk)
- 2Central Teaching Laboratories, University of Liverpool, UK
- 3Department of Geography, Durham University, UK
- 4School of Geography, Politics and Sociology, Newcastle University, UK
- 5School of Geography and Planning, Sheffield University, UK
- 6School of Earth Sciences, Ohio State University, USA
- 7School of Ocean Futures, Arizona State University, USA
- 8School of Geographical Sciences, Bristol University, USA
Loss of glacier ice is contributing substantially to rising sea levels, and is negatively impacting up to 1.9 billion people globally who rely on meltwater for agriculture, drinking water, hydropower and other ecosystem services. Quantifying how glaciers are responding to ongoing climate change therefore has far-reaching implications, though a global observational assessment of this at an individual glacier scale is currently lacking.
Here, we leverage the Randolph Glacier Inventory v7.0 (RGI) dataset (baseline date: 2000), and imagery from the Sentinel-2 archive between 2020 and 2024 to establish the change in extent of the 181,402 small ice masses (area <= 2 km2) globally that are most vulnerable to climate change. We achieve this through developing a simple, highly automated approach to glacier extent identification in Google Earth Engine, analysing all cloud free imagery for the end of the melt season in each RGI region.
Our workflow derives thresholded Normalised Difference Snow Index (NDSI) glacier masks for each Sentinel-2 image where at least 95% of the RGI outline area is visible, with the area of each contiguous ice/snow patch calculated using object based connected component analysis. To minimise potential false positives associated with ephemeral snow cover, the resulting masks for each glacier are ranked smallest to largest by the largest ice patch observed, before a final glacier mask is obtained from the areas identified as ice in at least two out of the three top ranked images. Results are compared to custom ERA5-Land reanalysis baselines to highlight the likely climate drivers of these changes, while CMIP6 climate simulations are used to project potential future change.
Our results highlight that significant global glacier loss and fragmentation has already occurred since 2000, and is likely to continue with future projected warming. This demonstrates recent glacier vulnerability to climate change and that negative impacts arising from glacier loss will likely become more acute on timescales much shorter than a human lifespan. In the International Year of Glacier's Preservation, this analysis therefore has tangible use for establishing the sensitivity of glaciers to future climate change, communicating the global vulnerability of glaciers, and motivating calls for action.
How to cite: Lea, J., Brough, S., Chudley, T., Davies, B., Ely, J., King, O., Lamantia, K., Larocca, L., and Maussion, F.: Significant global loss and fragmentation of glaciers since 2000, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12214, https://doi.org/10.5194/egusphere-egu25-12214, 2025.
