High-Resolution Glacier Mapping of Folgefonna, Western Norway, During Its ‘Little Ice Age’ Maximum and Subsequent Retreat

The Little Ice Age (LIA) is crucial for understanding the pre-industrial state of the cryosphere. Reconstructions often extend modern glacier inventories to LIA moraines, assuming minimal changes in high-altitude regions— a questionable premise for plateau icefields and other ice masses with top-heavy hypsometries. Using geomorphological mapping based on a wide range of high-resolution remote sensing data, including Sentinel-2 satellite imagery, we mapped the LIA extent of the Folgefonna icefield, Western Norway, in the highest attainable detail, distinguishing its geomorphological signature from earlier Holocene advances. A notable distinction was the contrast between densely vegetated pre-LIA surfaces and sparsely vegetated areas characteristic of the LIA. In steep topographical regions, talus cones outside the LIA boundary remained glacially undisturbed, while those within were often reworked into glacial drift, losing their original form. Other key indicators of the LIA boundary included fresh glaciofluvial fans below moraines. The identification of these distinguishing features may improve the accuracy of LIA reconstructions, which in turn may contribute to better glacier inventories and provide a more reliable foundation for assessing long-term glacier dynamics and changes in the cryosphere.