Unintended Consequences of Lights in Carlsbad Caverns

Being so used to having almost anyplace lighted so people can see their way, I hadn’t thought much of the lighting of the largest natural underground wonders in the United States. My first trip through the Big Room of Carlsbad Caverns was on Thanksgiving Day. We arrived shortly after this amazing natural wonder opened to the public. With so few people there, we were able to have parts of the path in the Big Room of Carlsbad Caverns to ourselves for minutes at a time.

It took a few minutes for our eyes to adjust, especially my companion who is due to have cataract surgery in a few months. The illumination was subdued. In some places it seemed there had at one time been lights that were now either burned out or turned off. Where we could see, we stood in awe before the amazing natural growths hanging from the ceiling or coming up from the ground.

Since most people were at home getting ready for their Thanksgiving meal, we were able to have some long conversations with the various park rangers that walked throughout this expansive underground wonder. One of our questions was about lighting.

The ranger told us that the lighting placement was designed by an expert in the theater. There used to be much larger and brighter lights spread throughout the Big Room. After a while an unintended consequence was noted. Green algae began to appear on the walls. This hadn’t happened before because Carlsbad Caverns had been pitch black before people wanted to be able to see what was inside. The earlier explorers came down with either oil lamps or the lamps on hard hats miners would wear. These did not produce algae growth.

To prevent the green growth on the wet walls of Carlsbad Caverns, some bulbs were turned off and the intensity of others was decreased. Although this reduced the algae growth, it also decreased what you can see. If we had thought of it, we would have brought a high intensity flashlight. This is strongly suggested on some of the guided tours where the paths are totally dark.

In the next few years the park service will be installing LED lighting. These do not promote algae growth and will last longer than what is now there. The park ranger explained that much more of the natural wonders would be seen and that LED would enable Carlsbad Caverns to stay in its more natural state… if you dismiss the fact that “natural” means pitch black.