Identifying and mapping very small mountain glaciers on coarse to high-resolution imagery

Small mountain glaciers are an important part of the cryosphere and tend to respond rapidly to climate warming. Historically, mapping very small glaciers (generally considered to be <0.5 km²) using satellite imagery has often been subjective due to the difficulty in differentiating them from perennial snowpatches. For this reason, most scientists implement minimum size-thresholds (typically 0.01–0.05 km²). However, when mapping on high-resolution imagery (<1 m) with minimal seasonal snow cover, glaciers <0.05 km² and even <0.01 km² are readily identifiable and using a minimum threshold may be inappropriate. For these cases, we have developed a set of criteria to enable the identification of very small glaciers and classify them as certain, probable, or possible. Our identification criteria are based on detailed ice surface structures (e.g. evidence of flow banding and crevasses) and diagnostic glacial landforms (e.g. moraines). Implementation of this scoring system should facilitate a more consistent and objective approach to identifying and mapping very small glaciers on high-resolution imagery, helping to produce more comprehensive and accurate glacier inventories.