Tasmania's World Heritage-listed Port Arthur Historic Site is under threat from climate change, according to the authority responsible for managing the major tourism destination.
Some heritage has already been lost at the Coal Mines Historic Site, also on the Tasman Peninsula, where convicts were once forced to perform hard labour.
David Roe, the archaeology manager for the Port Arthur Historic Site Management Authority, revealed to a parliamentary committee that climate change will be one of the "biggest issues" for the site in coming years.
The small burial site at Port Arthur, the Isle of the Dead, contains what is believed to be the world's oldest oceanic tidal benchmark.
Experts say it indicates the tide level has already risen 15 centimetres since 1841.
Dr Roe said the sea level rise was already having substantial impacts, and climate change would accelerate decay.
The authority has been working with researchers since 2014 to determine the likely effects — not only in relation to sea levels, but also other issues such as increasing soil salinity.
It has also received a grant from the Climate Change Office to undertake modelling of what inundation at Port Arthur will look like over the next century.
"We've engaged with local, national and international colleagues to work out what kind of responses might be appropriate, so that we preserve as best as possible the heritage assets that we've got, but also that we ensure that the values of those sites are not deleteriously affected."
Dr Roe said graves on the Isle of the Dead were not threatened, and while headstones were being monitored, they seemed stable.
Part of the island fell into the sea in the 1890s.
Dr Roe said some heritage had been lost at the Coal Mines site.
"At the Coal Mines beach we have lost material, that's been happening since about 2009, partly as a combination of storm surges but also day-to-day erosion," he said.
Greens leader Cassy O'Connor asked the questions about Port Arthur's management of climate change risk during Government Business Enterprise hearings.
She said with sea level rise already significantly impacting the Coal Mines, inaction on climate change would put Port Arthur's heritage further at risk.
"We welcome the work [Port Arthur Historic Site Management Authority] have done mapping out potential impacts over the next 100 years.
"This is what all government should be doing across the board to protect the wilderness and built and cultural heritage gems that make this island like no other place on Earth."
