Ice age: Franz Josef Glacier loses 1km within 10 years

One of New Zealand's famous glaciers has receded 1km over the last 10 years - and the retreat of the ice has been captured on camera.

And the Department of Conservation says the retreat is making it much more challenging to maintain safe access to Franz Josef's frozen field.

Victoria University glaciologist Dr Brian Anderson has released time-lapse video of the glacier from 2012 to 2019 that shows the environmental change.

The camera has not been operating since February last year so the footage ends there.

"The retreat between 2012 and March 2019 was 910m," Anderson told the Greymouth Star.

He said that between 2012 and last month, the total ice recession was 1.06km.

Franz Josef spans 12km and is a temperate maritime glacier in Westland Tai Poutini National Park on the West Coast.

DoC regional visitor planner Jock Edmondson said the access road to Franz Josef Glacier was less resilient to storms, mainly because of the gravels and debris left in the riverbed by the retreating glacier and because severe storms were more frequent.

Edmondson told the Greymouth Star that DoC and the NZ Transport Agency were working together to look at the long-term resilience of the access road.

In a typical month - and with no adverse weather - it was costing between $5000 and $8000 just to keep the road open.

Edmonson said routine maintenance included inspections and reporting, repairing seal, vegetation control and drainage.

In the decade ending 2018 at least $11.2 million was spent on the access roads to Franz Josef and nearby Fox Glacier.

In 2019 a major storm led to extensive damage to both access roads and emergency repairs to the Franz Josef access road alone cost $4m.

The Fox Glacier access road has been closed for several years because of a massive slip.