At the same time, the glaciers they were coming to see were receding fast.
University of Canterbury glaciologist Dr Heather Purdie said the biggest change had been the rapid development of pro-glacial lakes in these areas – meaning the actual terminal ice cliffs that tourists sought pictures of were moving further away from viewing points.
"For example, the Tasman Glacier terminus is now 5.5km distant and the Hooker Glacier terminus 2.5km distant from the main visitor viewing points," the study co-author said.
Large valley glaciers were also getting thinner, making access yet more difficult.
Over recent years, tourism operators had moved to overcome this by flying tourists in by aircraft – a point of contention among different groups, and also somewhat of an irony, given the threat CO2-driven climate change posed to glaciers.
A survey of tourists carried out as part of the study found that just half indicated that learning about climate change was an important part of their trip, even though 70 per cent expected the glaciers to recede further in the future.
Purdie saw it as a good opportunity to get the message across.
"Increasing the awareness of climate change in visitors who come to see these alpine regions would be beneficial," Purdie said.
"For example, visitors might start choosing to off-set their flights by purchasing some form of carbon credits.
"Wouldn't it be great if, after coming to see and experience glacier change, visitors felt inspired to make changes to their own personal lifestyles that will benefit the environment."
More generally, she saw a need to ensure that booming tourist numbers didn't compromise the natural spaces that had drawn visitors there in the first place.
"With appropriate resourcing and good design, managers can help protect quality visitor experiences, but this cannot be left to chance."
The Department of the Conservation was in the process of reviewing its 10-year management plan for Aoraki Mount Cook National Park.
But that work had been paused as DOC worked with South Island iwi Ngāi Tahu to understand the implications of a recent Supreme Court decision granting Ngāi Tai ki Tāmaki Tribal Trust the right to apply for exclusive rights to guided tours around Hauraki Gulf islands.
DOC's planning, permissions and land director Marie Long said part of the management plan would set limits on the number of aircraft landings allowed at each site.
"In terms of glaciers receding, the place this is the most visible is on the West Coast with Franz Josef and Fox glaciers," she said.
"Access to these glaciers by foot and by vehicle is increasingly difficult because of landslides and extreme weather events, and in turn this is increasing demand for scenic flights and heli-hikes.
"We use our management planning processes to engage on these difficult issues with the communities."
DOC was now looking at what response was needed across all areas of its management when it came to climate change impacts and sustainability, she said.
"Tapping into education as a way to raise awareness of climate issues will be an important part of this work."
