While glaciers around the world are shrinking because of global warming, 50 in New Zealand's Southern Alps have been gaining more ice mass over the last three years.
An annual survey by the National Institute of Water and Atmospheric Research (NIWA) using aerial photographs shows the glaciers have reversed a pattern in which they shrunk in four of five years between 1998 and 2002.
But NIWA climate scientist, Jim Salinger, said that while the glaciers were continuing to recover, they were still far from their ice-packed glory of a century ago.
He said the Frank Josef Glacier, in the Westland National Park, which descends about 10km from the main divide in the Alps to about 300m above sea level in temperate rain forest, was still much shorter than in 1900.
And the total volume of ice in the Southern Alps has been reduced by 25 to 30 percent as mean temperatures rose by 0.7oC.
Mark Mellsop, director of Franz Josef Glacier Guides, said the ice was advancing by up to about 1m a day.
"It's pushing a pile of rocks in front of it like a slow-moving bulldozer blade, so you can certainly see evidence of the advance," he told the Press newspaper in Christchurch.
The 14km Fox Glacier is growing about 70cm a day, according to Alpine Guides managing director Mike Browne, who said the advance had been especially noticeable over the last three months of winter.
He said guides had to cut new steps into the ice for guided walking groups regularly because old ones were being moved by the advancing glacier.
Salinger said that last year's gains were caused by heavier snowfalls in the Alps which had caused the seventh-largest increase in ice volumes since NIWA's aerial surveys began in 1977.
The World Glacier Monitoring Service has reported an average annual loss of half a meter in ice thickness since 1980 in monitored glaciers, demonstrating the effects of global warming.
But Salinger said New Zealand glaciers were boosted by extremely high rainfall, with more than 10m a year falling west of the Southern Alps' main divide.
Most glaciers, except for some in parts of Norway, were in areas of lower rainfall and were affected more quickly by rising temperatures.