Cave climate study at Yarrangobilly

Yarrangobilly Caves.

Research that hopes to reveal the impacts of humans and the external environment on cave climate is currently taking place at Yarrangobilly, as part of a new Australasian study that could potentially allow for better cave management in future. 

Humans have been visiting and exploring caves all over Australia for thousands of years, but how many have ever stopped to consider the impacts of their visit upon these subterranean marvels?

The Australasian Caves and Karst Management Association (ACKMA) is now investigating just this, rallying a team of experts and cave enthusiasts to take part in a study looking at cave climate and factors which may influence it. 

The idea came as a result of Covid-19 in early May last year, as lockdowns and a new way of living forced the closure of all visitor caves due to ‘social distancing concerns.

As a result, ACKMA decided these conditions would provide the unique opportunity to collect data and monitor cave activity free from human interference, especially as for many caves this was the first time in over a hundred years that no-one could go inside.

The study is looking at 26 different caves across Australia, New Zealand and Tasmania, including those at Yarrangobilly and Jillabenan.

Verified climate loggers inside and outside of the caves are currently recording both temperature and humidity data, information which will aid in understanding cave climate and sustainability – particularly the impacts of humans when visiting. 

Professor Andy Baker is a cave and karst researcher at the University of New South Wales (UNSW), who was asked to join the study due to his experience in cave research and monitoring.

Having already gone temporarily part-time in his teaching role at the university – to help cut costs during the worst of Covid – Professor Baker was convinced he would be spending his extra time ‘helping elderly neighbours’, so when the opportunity to coordinate the technical side of the study came about he was quick to accept. 

As cave research has progressed, there has been a continuous juggle between allowing visitors to experience the natural wonders of caves whilst also ensuring that the structures which have taken millions of years to form remain preserved. 

As well as Professor Baker, 17 other caving organisations had also volunteered for the ACKMA study, something that the Professor believed demonstrated a willingness from the entire community to continue to learn and improve upon their own carefully constructed management plans. 

“The organisation [ACKMA] is a caves management organisation, so everyone that has taken part is very keen to have a sustainable management of the caves,” he said.

Whilst the study is only relatively new – with data collection beginning in June and some caves continuing to be affected by Covid restrictions – the research has already recorded some interesting results.

Professor Baker explained that in some caves they have already observed a slight increase in recorded temperature caused by visiting tour groups – an increase which grew larger depending on the size of the group.

For some caves, this relationship between tour groups and cave temperature is so distinct that the data clearly shows when and what time these groups visited, due to the subsequent rise.

However, just as quickly as this temperature increased due to large numbers of visitors, it also decreased at a similar rate once they left the cave – soon returning to its natural temperature state. 

Professor Baker said that this is extremely positive and highlights that the management plans of most caves have been working extremely well, to limit any long-term human impact. 

“I think it shows the caves are being very well managed and that the tour groups sizes are appropriate and sustainable,” Professor Baker said.

“If any of these caves are mismanaged and they allow 300 people at any one time inside for example – and we start to see all these environmental impacts – we’ll see that through the climate data, but no one is doing that.

“All these organisations are very keen to be environmentally friendly and sustainable and they’re [clearly] doing the right thing.”

The Professor also said that so far the recorded seasonal trends in climate data between summer and winter months, are greater than any temperature changes caused by visitors, indicating that human exposure is having little long-term impact. 

“When the natural variability is bigger than anything from tourists… you know you’re doing the right thing,” he said. 

Changes in temperature can have numerous effects upon the preservation of a cave and its ecosystem, with organisms in subterranean environments often more specialised to specific conditions – meaning any changes can have dramatic impacts.

To prevent this, limiting tour sizes and fitting LED lights are both examples of strategies that have been introduced by cave management to minimise any potential temperature increases.

Some caves are also able to regulate this temperature themselves through ventilation, a process that regulates a build-up of carbon dioxide which visitors also contribute to.

“If people go in, they’re going to breathe out more carbon dioxide and that can accumulate and you might be heating up the cave at the same time.

“If you have a cave that is very well ventilated with the outside air, then that heat and carbon dioxide dissipates, but then if you have less ventilation it can accumulate.”

As well as temperature and carbon dioxide, dust, skin and oils deposited – mostly unwillingly – by humans can all also diminish both the formations and the ecosystems within the caves.

This is because these substances disrupt the growth of the calcite crystals, meaning it is crucial that visitors do not touch stalactite and other rock surfaces when inside. 

Professor Baker also said that simply monitoring temperature can be used as a good baseline indicator for all of these other effects by humans on the cave, as temperature change can be linked with the duration of tours and therefore how long the caves are exposed to potential human interference. 

Yarrangobilly’s karst landscapes were created from a belt of limestone laid down about 440 million years ago.

Almost all cave formations can be seen at the precinct, with these karst environments acting as a form of natural time capsules – preserving evidence of climate change, floods, droughts, fires, animal and human activity.

As such, Yarrangobilly has previously hosted numerous researchers from universities, nuclear science organisations and even Snowy Hydro, and now is undertaking this cave climate study at Jillabenan Cave.

Jillabenan is also rather significant as like many other caves it has also been affected by several man-made changes over time. 

Amongst its fantastic array of natural formations, the cave features wheelchair accessibility rails, and a former ‘wishing well’.

In the case of the ‘wishing well’ – a natural pool of water which visitors were encouraged to throw coins into when the cave was privately owned – there is a slight green stain from where the copper coins have sat in the water for many years, and begun to stain the rock.

This green, however, is slowly being covered by natural rock, and today is only visible to a keen eye.  

Today, most caves in Australia are very well managed and human interference is minimal, and the research of the ACKMA study supports this so far. 

Because of Australia’s relative isolation and population size, Professor Baker also said that the country is lucky that there aren’t even larger numbers of people visiting caves like there are in many other countries – numbers which make cave preservation more difficult. 

The climate study at Jillabenan and the rest of the caves will continue some time into the future, and when social distancing regulations are removed will again provide new results for Professor Baker and his team to study.