Abstract:
Downwasting has altered the morphology of the terminus region of the Tasman Glacier between 1971 and 1993. Rapid melting began in the late 1960s in a few isolated melt ponds in the centre and in a small elongated lakelet at the eastern lateral moraine. These ponds and lakes grew rapidly in size during the 1970s and coalesced to form a large melt lake by about 1990. This melting has led to a disintegration of the entire terminus region, and now occurs as far as 3 km upstream from the old terminus. A poorly understood convection mechanism prevents suspended silt from settling and causes the uniform grey colour of the lake (here called "Tasman Lake'). Surveys demonstrate how the terminus region of the largest New Zealand glacier has disintegrated over the past 22 years.
