Director of the Colong Foundation for Wilderness, Keith Muir said Australia's ski season would be reduced significantly by 2050, which would rule the ski resort proposal by Vail Resorts at Perisher pointless.

"You shouldn't be building this 800 bed monster for skiing when the snow's going to be gone," Mr Muir said.

"Once the capital is invested they'll twist the whole park upside down to make it work."

"We're trying to use this as a bit of a lever to wake people up: the resorts are going because the snow is going."

By 2050, the region's 112-day snow season would be reduced by 20-55 days at best if global emissions were not reduced, data from a 2012 CSIRO report on Victoria's snow fields and a 2015 national climate change report suggest.

Another report commissioned by the Australian Alpine Co-ordinating Council indicated climate change threatened ski resorts in Australia, with resorts forced to rely on snow-making as 2050 approached, creating an unreliable and costly ski season.

Michael Grose, research scientist at CSIRO's Climate Science Centre, said while there would be occasional good seasons, the long-term trend was moving towards a reduction in Victoria and NSW's snow.

"The lower elevations are expected to feel impacts sooner and more strongly and so the higher elevation sites like Kosciuszko will feel that a little bit later," Mr Grose said.

Mr Muir said development projects like the one at Perisher were difficult to challenge, but the foundation was concerned the development would set a precedent of mass construction in Australia's national parks.

"Nothing will be sacrosanct, the land we set aside for nature will be developed then there will be nothing left," Mr Muir said.

"It's an absolute tragedy that the snow's going, it's an even bigger tragedy that we want to turn the park into something else and that's really what the fight's all about."

A concept plan for Perisher Village was approved under the controversial and since repealed Part 3a of NSW's Environmental Planning and Assessment Act 1979, which allowed state planning ministers to directly approve projects without approval from local councils or heritage and parks acts.

The concept plan for Perisher Village was set to expire on October 2, 2016 unless some form of physical commencement had begun, which Mr Muir claimed to have proof this hadn't happened.

Vail Resorts purchased Perisher for $176.6 million last year from James Packer but in a statement to Fairfax Media, Vail Resorts said they had no rights to develop Perisher Village and would not pursue development.

A spokesperson for NSW's Department of Planning and Environment said they were aware physical works on the Perisher Village Concept Plan had commenced on June 20, 2016 and department staff had since inspected the site and confirmed work had commenced.

Mr Muir said even the installation of a park bench and walking trail would count as physical commencement on the project.

The project has been in its infancy as far back as November 2001 with approval in September 2006 given under Part 3a by then-NSW Minister for Planning Frank Sartor.