A satellite image of Okjokull, a former glacier in Iceland, from August 1, 2019, shows a scattering of thin ice patches.

(NASA Earth Observatory image by Joshua Stevens using Landsat data from the U.S. Geological Survey)

At a Glance

Okjokull was declared dead in 2014 when it was no longer thick enough to move on its own.Now, Ok is just a small patch of ice at the top of a volcano in Iceland.The plaque is said to be the first monument to a glacier lost to climate change anywhere in the world.

The message is sobering.

"Ok is the first Icelandic glacier to lose its status as glacier. In the next 200 years all our main glaciers are expected to follow the same path."

The warning appears on a plaque commemorating the loss of Okjokull, a glacier in Iceland that was declared dead in 2014 when it was no longer thick enough to move on its own. Jokull means glacier in Icelandic. Ok is now just a small patch of ice at the top of a volcano northeast of Reykjavik, the capital.

On Sunday, Iceland's Prime Minister Katrin Jakobsdottir, other officials and scientists gathered to lay the plaque at the volcano.

“This will be the first monument to a ,” Cymene Howe, an anthropologist at Rice University and one of the scientists on the trek, said in July. “By marking Ok’s passing, we hope to draw attention to what is being lost as Earth’s glaciers expire. These bodies of ice are the largest freshwater reserves on the planet and frozen within them are histories of the atmosphere. They are also often important cultural forms that are full of significance.”

Icelandic author Andri Snaer Magnason wrote the words on the plaque.

"You think in a different time scale when you're ," Magnason told the BBC. "You start to think that someone actually is coming there in 300 years reading it.

Okjokull covered more than 6 square miles in 1890. By 1978, it was less than 1 square mile, according to NASA, which recently .

These satellite images show Okjokull on September 14, 1986, and on August 1, 2019. The Icelandic glacier was declared dead in 2014.

(NASA Earth Observatory images by Joshua Stevens using Landsat data from the U.S. Geological Survey)

In 2014, "we made the decision that this was no longer a living glacier,," Oddur Sigurdsson, a glaciologist with the Icelandic Meteorological Office, told AFP. To move under its own weight, a glacier needs to be about 130 to 165 feet thick, Sigurdsson said.

Howe and Dominic Boyer, also a Rice University professor, made called "Not Ok" in 2018, and came up with the idea of a memorial during filming.

The message on the plaque commemorating Iceland's Okjokull was written by Icelandic author Andri Snaer Magnason.

(Rice University/Dominic Boyer and Cymene Howe)

"People felt this was a real loss, and that it deserved some kind of memorial," Boyer told the BBC. "Plaques recognize things that humans have done, accomplishments, great events. The passing of a glacier is also a human accomplishment — if a very dubious one — in that it is anthropogenic climate change that drove this glacier to melt."

Magnason, the author, said. "Climate change doesn't have a beginning or end and I think the philosophy behind this plaque is to place this warning sign to remind ourselves that historical events are happening, and we should not normalize them. We should put our feet down and say, okay, this is gone, this is significant."

The full plaque reads:

"A letter to the future

"Ok is the first Icelandic glacier to lose its status as glacier. In the next 200 years all our main 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 ends with the date, August 2019, and the concentration of carbon dioxide in the air globally: 415 parts per million.

Sigurdsson said he fears it may already be too late to save many of the Earth's glaciers.

"The inertia of the climate system is such that, even if we could stop introducing greenhouse gases into the atmosphere right now, it will keep on warming for century and a half or two centuries before it reaches equilibrium," he said.

A monument is unveiled at site of Okjokull, Iceland's first glacier lost to climate change in western Iceland on August 18, 2019. (Jeremie Richard/AFP/Getty Images)