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“It’s undeniable that the average firn line is creeping up,” Volken said, referring to the line across glaciers at which exposed glacier ice transitions to the snow-covered surface of a glacier.

Ice and firn, or dense snow leftover from previous seasons, also disappeared from the ridge.

Much of the ice on the continent of Antarctica is actually a form of consolidated snow called firn.

During large melt events, meltwater on the surface can seep through the snow and into firn, or a layer of compacted snow that is not yet compressed into glacial ice.

Depending on the temperature of the water, snow and firn, the meltwater can refreeze and can create ice lenses.