Melting Glacier: A 37-Year (1984-2020) High-Resolution Glacier-Cover Record of MT. Kilimanjaro

Shuai Yuan, Juepeng Zheng, Lixian Zhang, Runmin Dong, Yile Xing, Yuhan She, Haohuan Fu, Ray C. C. Cheung

Abstract: Commonly recognized as an important symbol of the tropics and global warming, the glacier loss on Mt. Kilimanjaro has received worldwide attention for decades. In this paper, we propose a high-resolution glacier-cover (GC) record of Mt. Kilimanjaro over the period from 1984 to 2020, using a novel deep learning-based semantic segmentation method and Google Earth images, as well as digital elevation model (DEM) and ERA5-Land (ERA5) for snowline and temperature variations analysis. Our method achieves an accuracy of 94.37%, which proves the model's capability to record the GC areas precisely. The results show that (1) the GC area dramatically decreases from 19.2 km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> to 3.6 km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> during 37 years, which decreases about 4% and 2% per year from 1984 to 2000 and from 2000 to 2020 respectively, (2) the snowline altitude rises from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4,651 m$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5,088 m$</tex> by about <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$437 m$</tex> , and (3) the average <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5,000 m$</tex> air temperature on Mt. Kilimanjaro increases from −2.1 °C to −1.1 °C by about 1 °C. This study indicates that there will be no GC within a few decades if the current loss continues.