Last semester, I was tasked with completing a remote sensing project about ANYTHING I wanted to look at. But who knew choosing a topic would be the hardest part? I thought hard and long about what I wanted to do- terrestrial or marine? environmental vs anthropogenic? After much thought, I chose to quantify glacier retreat in the Great Aletsch Glacier Region using the normalized difference snow index (NDSI) from 2001 to 2025.

The Great Aletsch Glacier is part of the Swiss Jungfrau-Aletsch UNESCO World Heritage Site, covering approximately 824 km^2. However, Switzerland is experiencing a higher rate of warming (2°C since the pre-industrial era) compared to the rest of the world. As a result, the Great Aletsch Glacier region has lost 3km in length and 200m in height. These facts sparked my interest and I wanted to know (approximately) how much of the Great Aletsch Glacier region has retreated due to intensifying global warming.

To do so, I ran a change detection analysis using Landsat imagery from 2001 and 2025. After, I quantified the change by ‘pixel counting’ (amount of pixels* 30m* 30m/1,000,000,) and proceeded with an equalized stratified random sampling point accuracy assessment and confusion matrix.

Although this may not seem like an intensive project, the results from each step are very fascinating!

Visually, you can see the overall NDSI change over the 24-year period. Specifically, you can see the growth of proglacial lakes and the retreat of the terminals. Most notably, the tributaries are progressively becoming more defined as human-intensified climate change continues to disproportionately affect the Eastern Bernese Alps.

The final output is shown to the right. This map highlights glacial retreat in red and glacial advancement in green, overlaid on the 2025 Landsat imagery. As you can see, many areas have experienced glacial loss over 24 years. However, I would like to draw your attention to the green area (a glacial lake). This area shows that there is advancement occurring, but that is not the case. Since the thresholds for both water and ice are very, very similar, I could not separate them, and due to time constraints, I could not remove the lakes from my analysis!

Overall, I got glacial retreat values of 331 km^2 (Transition from ice-covered to ice-free features) and 2068.6 km^2, showing no change over the 24-year period. And of course, I would like to mention that there are many external variables influencing the glacial retreat, as well as small human errors when running the classification!

I really enjoyed this project and want to expand on it in the future or do something similar!