New Zealand's tallest mountain has just been knocked down to size.
Aoraki/Mt Cook has been listed as 3754m above sea level, but high accuracy GPS data obtained during an Otago University climbing expedition in November reveals it's actually 3724m, or 30m shorter.
Pascal Sirguey from the Otago National School of Surveying says the change from the previous measurement, made after a massive rock-ice collapse in 1991, was due to a 20-year reshaping process.
Dr Sirguey says it appears there was still a relatively thick ice cap after that collapse but that it was probably out of balance with the new summit ridge shape.
"As a result the ice cap has been subject to erosion over the past 20 years," he said.
"While the effects of climate change may spring to mind as an explanation, it is probably a case of a simple change in the geomorphology of the mountain."
Despite Mt Cook's slump it's still more than 200m taller than New Zealand's second-highest mountain, the neighbouring 3497m Mt Tasman.
The four-person climbing team did not reach the summit, but instead took measurements with state-of-the art receivers from the top of the ice cap a few metres away.
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