In the 1950s, mountaineering legend Lou Whittaker took thousands of people to see the ice caves. He was fresh out of college at the time. A guided summit climb cost $28. The ice caves were just $5. Few people climbed Rainier back then.

“We’d rappel off the balcony on the lodge and land on the floor and say, let us tell you about the ice cave trips, and see if we could talk them into the five dollar fee,” Whittaker says.

Whittaker still vividly remembers the caves. “You could walk in 200 feet and still get this eerie green blue light which was awesome to see. And the cold air, even on a real hot day,” he says.

Two factors determine whether a glacier advances or retreats: how much snow falls in the winter and how warm it is during the summer.

Most glaciers in the Northwest have been retreating since a little ice age in the 1800s came to an end, They’ve retreated more quickly as carbon has accumulated in the atmosphere and average temperatures here have risen.

The Paradise Glacier thinned so dramatically that a band of rock split the glacier in two, leaving the lower half starved of ice. The caves formed beneath the thinning ice. In 1940, the park’s naturalist wrote that the lower Paradise Glacier was stagnant and predicted it wouldn’t last long.

But the 1950s and 1960s were good decades for snow at Rainier, and many of the glaciers there stopped retreating.

By the late 1970s, big holes opened in the ceiling of the caves, and they grew more dangerous. Within two decades, the lower half of the Paradise Glacier had melted.

The ice caves were gone.

“We live in a warming period. And times, they are a changing,” Whittaker says.

Paul Kennard, one of the park’s geologists, visited the Paradise Ice Caves in 1981, when very little of the glacier was left. At the time, he wasn’t alarmed.

“I think we saw the variations in the glaciers as just being a normal thing” he says. “We didn’t see this long term trend.”

Now, Kennard says, he sees it as a reflection of global climate change. Every one of Rainier’s glaciers is at its historic minimum. Between 2003 and 2009, Rainer lost ice six times faster than it had in previous decades.