“The glacier’s melt rate is exponentially increasing,” Thompson said. “It’s similar to visiting a terminal cancer patient, and documenting the change in their body, but not being able to do anything about it.”
Globally, glacier melt is a major contributor to sea level rise, which, along with warming ocean waters, can lead to more frequent and more intense storms.
Thompson said the mountaintop glaciers around the world contribute between a third and a half of the annual sea level rise in the Earth’s oceans.
“They are much more vulnerable to the rising temperatures because they’re small and they’re warmer – they’re closer to the melting threshold,” he said. “Ice is just a threshold system. It is perfectly happy at freezing temperatures or below, but everything changes at 32 degrees Fahrenheit.
Climate change has increased the temperature of the atmosphere, which means the air around the glacier is warmer. But it has also changed the altitude at which rain turns to snow. That means that where snow once fell on top of the glacier, helping rebuild its ice year-by-year, rain is now falling. That rainfall is the kiss of death for a glacier.
Water absorbs more energy – more heat – from the sun than snow does, so increasing the water on top of the glacier warms the glacier even more, accelerating the melting of the remaining ice.
“If you want to kill a glacier, just put water on it,” Thompson said. “The water basically becomes like a hot water drill. It goes right through the ice to the bedrock. So, when water starts to accumulate on top of the glacier, the glacier starts to melt much faster than current models predict as the models are driven by temperature changes but don’t account for the effect of water accumulating on the glacier surface.”
Once water starts streaming through crevasses in the glacier to the bedrock, it also begins to lubricate the glacier along its bottom. This eventually creates a warm pool beneath the glacier, which may cause the glacier to slide, ever-so-slowly, down the mountain to lower elevations where temperatures are warmer.
Such was the case with this glacier, the researchers learned when they first drilled in 2010. The cores they brought to the surface showed meltwater at the base of the glacier as well as at the top.
That melt can affect the information scientists are able to learn from the cores, which normally provide year-by-year data records of the climate around the glacier. As the glacier melts, those year-by-year records can become blurred. In this case, however, the cores still showed evidence of El Niño events throughout the ice cores’ history. Because so much of the glacier has melted, the cores hold data for only the last 50 years, despite the fact that these glaciers have likely occupied these mountaintops for the last 5,000 or so years.
The glacier’s disappearance is a cultural loss, too, Thompson said: The indigenous people who live around the mountain worship it.
“The ridges and the valleys are the arms and legs of their god, and the glacier is the head,” he said.
When the team drilled in 2010, some of the elders of the indigenous communities protested: “In their words, they thought we were ‘drilling into the skull of their god to steal the god’s memories,’” Thompson said. “I told them that was exactly what we were doing. We needed to preserve those memories because the glacier was going to melt.”
That started a debate throughout the indigenous community, weighing whether the team should be allowed to continue its research mission to learn the history contained within the ice, or was it more important that the glacier remain undisturbed? Thompson said the elders of the community were strongly in favor of kicking the research team out while the younger people, he said, wanted the mission to continue. In this case, the younger people won.
“It was the young people who were saying, ‘Have you not seen what’s happening?’” Thompson said.
Other Ohio State researchers on this study are Ellen Mosley-Thompson, Mary E. Davis, Ping-Nan Lin, Julien P. Nicolas, John F. Bolzan, Paolo Gabrielli, Victor Zagorodnov, and Bryan G. Mark. This work was funded in part by the National Science Foundation.
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December 10, 2019 at 03:00AM
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