This image shows holes in the ice where dark pebbles heated up enough from the sun’s rays to melt straight down through to the ground. I went to a job interview last week and mentioned that if a debris layer is thick enough, it will insulate the underlying snow and ice, rather than melt it. The idea of two modes or two different responses of ice melt depending on debris thickness made one of the faculty members very curious. Do other disciplines not discuss thresholds? I bet even poetry has some. Thresholds are pervasive in climate science and geology it seems.