RIP, Ok glacier.

With a theme of fighting climate change, about 100 Icelanders have said farewell to what once was a glacier. Scientists said it was the first of Iceland's glaciers to disappear because of climate change.

Iceland geologist Oddur Sigurðsson declared the Okjokull glacier extinct about a decade ago. But on Sunday he brought a death certificate to the made-for-media memorial.

About 100 years ago, the glacier covered almost 6 square miles of a mountainside in western Iceland and measured more than 160 feet thick.

A plaque has been installed at the site of the former glacier, which reads: “In the next 200 years, all our glaciers are expected to follow the same path, This monument is to acknowledge that we know what is happening and what needs to be done. Only you know if we did it.”

It's the first monument to a glacier lost to climate change anywhere in the world, said anthropologist Cymene Howe of Rice University in Houston, in a statement last month. “By marking Ok’s passing, we hope to draw attention to what is being lost as Earth’s glaciers expire."

The English name of the glacier is "Ok glacier."

Residents Sunday reminisced about drinking pure water thousands of years old from Ok.

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"The symbolic death of a glacier is a warning to us, and we need action," former Irish president Mary Robinson said.

"We see the consequences of the climate crisis," Icelandic Prime Minister Katrín Jakobsdóttir said. "We have no time to lose."

The memorial also carries the words “415ppm CO2,” referring to the record-breaking level of 415 parts per million of carbon dioxide recorded in the Earth's atmosphere in May.

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"I know my grandchildren will ask me how this day was and why I didn't do enough," said Gunnhildur Hallgrimsdottir, 17.

“One of our Icelandic colleagues put it very wisely when he said, ‘Memorials are not for the dead; they are for the living,'” Howe said. “With this memorial, we want to underscore that it is up to us, the living, to collectively respond to the rapid loss of glaciers and the ongoing impacts of climate change.

"For Ok glacier it is already too late; it is now what scientists call ‘dead ice.'”

Contributing: The Associated Press