Yosemite’s Disappearing Glaciers

By Jennifer Mu

My husband and I spent a week in Yosemite National Park in April. It had been two decades since our last trip to Yosemite.

A week before we left home, I heard on the radio that Yosemite’s last two glaciers are fast disappearing. I went to the National Park’s website, and it predicted that Lyell’s Glacier could completely disappear in 2020. I thought this could be our last chance to see it, or whatever is left of it.

Melting glaciers are not news. It has been happening all over the world. From Himalaya to Peru, from the Arctic to Antarctica, glaciers are fast retreating. For years I’ve had this sense of urgency to see glaciers before they have all melted away.

We drove to the Canadian Glacier National Park in British Columbia years ago and there was not much there. On a tour to the Arctic, we saw retreating glaciers and chunks and chunks of floating ice with beautiful blue hues. We still haven’t made it to the Glacier National Park in Montana, but have read articles about its shrinking glaciers. The melting glaciers in Yosemite are too close to home to not check them out in person.

Yosemite’s Glaciers

Studies of Yosemite’s glaciers began in 1872. John Muir drove pine stakes into an ice field on Mount Maclure to measure its movement. He eventually convinced the world glaciers carved Yosemite Valley.

Yosemite's disappearing glaciers
Yosemite’s majesty is inspirational in all seasons, yet we are ruining its ecosystem.

After it was designated a national park, Yosemite’s scientists continued the regular survey of the two remaining glaciers, Lyell and Maclure. The most recent data indicated that the glaciers’ surface has shrunk from 300 acres to 60 acres, an 80% loss of glacier ice, since 1883 when they were first mapped and photographed. The Lyell Glacier has completely stopped moving, so it’s no longer a glacier by definition. In other words, it’s dead. Yosemite’s geologist, who was interviewed on the NPR program that I was listening to, described today’s Lyell Glacier as “a stagnant ice patch.”

Glaciers have come and gone with nature’s cycles, advancing and retreating about every 100,000 years. Scientists agree the current accelerated melting of Earth’s glaciers is due to the warmer temperatures caused by human activities. I don’t need to repeat here the consequences of melted glaciers, rising sea levels and warmer sea surface temperatures; we are already living some of them now.

Theoretically, more snow in the winter and colder temperatures could restore the glaciers. But the Earth is already in such deep trouble that I don’t know how to stay optimistic. There were news reports a Russian town near the entrance to the Arctic Ocean registered a record high 84 degrees on one weekend in May this year. The town’s average high temperature is normally around 54 degrees that time of year. During the same weekend Hawaii’s Mauna Loa Observatory registered the highest concentration of carbon dioxide in the atmosphere in human history.

The Importance of Yosemite’s Glaciers

Yosemite's disappearing glaciers
A calf from a glacier casts a blue shadow on the ocean.

According to Yosemite Park’s geologist, even if we stop emitting greenhouse gases today, it would be too late for Lyell and Maclure. Click here to see photos demonstrating the retreating glaciers. This is not something we can just feel a brief moment of sadness about and forget. The effect of their disappearance will touch each of us in the Bay Area in our lifetime.

These two glaciers provide for the headwaters of the Tuolumne River, keeping it flowing during summer and fall. The river is the primary source of drinking water for San Francisco. It also provides irrigation water for parts of the Central Valley. The glacier’s deaths will bring drastic changes in the ecosystem – that we are part of – for centuries. The lifestyle we know, and take for granted, will be no more.

It also means future generations will only learn about these glaciers, and their significance to the ecosystems and communities relying on them, in the park museum.

Courtesy of the Rossmoor News, July 10, 2019.  Email Jennifer Mu at barnhartmu8833@gmail.com

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