Waitomo Caves shut ‘five times’ due to high CO2

One of New Zealand’s most popular tourist attractions, the Waitomo Glowworm Caves, had to shut up shop a number of times over summer because of excessive carbon dioxide levels, driven partly by visitor numbers.

The chair of the cave’s environmental advisory group is worried what burgeoning tourist numbers could mean for the cave, and said the potential to damage it was very high.

About half a million people visit the Waitomo Caves every year, making them the most-visited caves in the Southern Hemisphere.

Tourism Holdings is the leaseholder and operates the Discover Waitomo Group, which includes the Waitomo Glowworm Caves, Ruakuri Cave and Aranui Cave.

The chief executive of Tourism Holdings, Grant Webster, said the glowworm caves have been shut down about five times over summer because the level of carbon dioxide in the caves has gotten too high.

He said this was not isolated, and had happened over the last few years.

The glowworm caves could be closed anywhere from half an hour to a few hours and visitors were usually very understanding when it happened.

Mr Webster said the carbon dioxide level was not something that could be directly attributed to visitor numbers, and had a lot to do with climatic conditions and ventilation of the caves.

‘Gaping hole’ in legislation

But the chair of the external environmental advisory group, University of Auckland professor Chris De Freitas, who is an expert scientist in this field, said he had no doubt that there was a close link between high visitor numbers and high carbon levels.

“The more people in the cave at any one time, the higher the concentration of carbon dioxide in the atmosphere, and of course that’s a key facet of the physical environment of the cave and it affects the cave’s environment as well as the ecosystems within the cave.”

Dr de Freitas said the caves were incredibly sensitive and damage could take tens of thousands of years to heal.

He believed the government has a custodial role to play, similar to the Department of Conservation’s role with national parks or marine reserves.

Dr de Freitas said the fact this was not in place was a “gaping hole” in New Zealand’s environmental legislation.

“There’s no protection at all for caves, or no management guidelines for show caves or commercial tourist caves – this is in sharp contrast to say places like Croatia, Slovenia, Italy.”

Dr de Freitas said Tourism Holdings managed the caves in a very responsible and conscientious way, which was sheer good luck because there was no legislative obligation for the company to do so.

He said there were caves in New Zealand that could be vulnerable to mismanagement, but he did not want to name them.