A forgotten Cold War experience has revealed its frozen secret: it’s bad news for the planet

At first Andrew Christ was ecstatic. In the ground, taken at the bottom of the Greenland ice cap, he had discovered the remains of ancient plants. Only one other team of researchers had found vegetation under the kilometer-high mass of ice.

But then Christ determined how long it had been since this ground had seen sunlight: less than a million years. Just a blink of an eye in geological terms.

And it occurred to him. If ever plants grew in various places on the surface of Greenland, this meant that the ice now covering the island had completely melted. What if the entire Greenland ice sheet had melted once in the not too distant past, it meant i could disappear again.

Oh my God, he thought.

The results, published Monday in the Proceedings of the National Academy of Sciences, indicate that the northern hemisphere’s largest ice reserve may collapse due to a relatively small increase in temperature over a long period of time. This makes it even more vulnerable to human-caused warming, which causes the Earth to heat up faster now than at any time in its history.

“We know the Greenland ice cap has that threshold,” Christ said, and humanity is pushing it.

Greenhouse gas emissions from human activities have already increased global average temperatures by more than 1 degree Celsius (1.4 degrees Fahrenheit) since 1880. Greenland is losing ice at its fastest rate since humans invented agriculture, which has caused sea level to rise by around 14 millimeters over the past half century.

If the entire ice cap on the island were to melt now, global sea level would rise by more than 20 feet (about six meters).

“We don’t want to see what that will look like,” said Christ, a geologist at the University of Vermont. “It underscores the urgency of having to change the way things are going now.”

The story of this soil sample is almost as dramatic as the data it contains. It comes from the bottom of an ice core taken during “Project Iceworm,” a failed Cold War effort to hide nuclear missiles under Greenland ice.

Camp Century, in the far northwest of Greenland, was to be the basis of the US military project. Houses, dining rooms and medical facilities, all powered by a nuclear reactor, have been carved out of the ice.

In the “batalla entre el hombre y la naturaleza … el hombre ha llevado su mayor logro científico, el poder del átomo, a la cima del mundo”, declared el locutor Walter Cronkite durante una visita in 1960. “¿Pero puede vivir here? Can he stop the crushing force of Eternal Ice?

To hide the true purpose of the company, the United States asked scientists to research the site. Among the experiments was a one-of-a-kind project to obtain an ice core covering the entire depth of the ice cap.

“This ice core revolutionized our understanding of Earth’s past climate,” Christ said. By measuring the types of oxygen in each ice sheet, the researchers were able to get a rough estimate of how hot it was when the water froze. Analyzes of ice cores from Greenland and elsewhere have enabled scientists to reconstruct a record for global temperatures dating back tens of thousands of years.

But the roughly 12 inches (about 30 cm) of soil at the bottom of the Camp Century ice core has never been investigated.

During, The craze for the “Iceworm Project” became apparent when the ice began to move.. The tunnels collapsed. The team was crushed. The nuclear reactor was quickly dismantled and the field abandoned. All the scientific materials collected were sent to laboratories and were rarely redesigned.

More than half a century later, glaciologist Jørgen Steffensen was making an inventory at the University of Copenhagen’s ice carrot store when he came across what appeared to be cookie jars filled with sand, clay. and earth. Curious, he sent them to a few colleagues for analysis.

The samples arrived at the University of Vermont in coolers filled with freezer packs. Christ, then a doctoral student, was tasked with examining the material, extracting intriguing fragments and placing them on microscope slides.

He leaned down to look, then his eyes widened. “These are twigs and leaves and moss,” he said, “freeze-dried for hundreds of thousands of years. It literally looks like they could’ve been alive yesterday. “

Christ summoned his advisor, Paul Bierman, and an undergraduate assistant to the lab. They all started jumping, laughing and screaming, as a group of high school tourists stared at them in bewilderment.

“This is the most exciting day of my scientific life and you are here for it,” Christ remembers telling the teenagers.

The fossils were passed on to plant experts for further analysis, and Christ set out to try to determine when they might have grown. He used a technique called cosmogenic nuclide dating, which estimates how long rocks have been buried by analyzing the particles created when materials are exposed to radiation from space.

Early analyzes suggest that the plants are no more than a million years old, which means they must have grown during the epoch of repeated ice ages known as the Pleistocene. Meanwhile, greenhouse gas concentrations in the atmosphere were well below current levels, and the Earth was rarely as hot as it is today.

“If we had found a much older age it would have been awesome, but it might not have been so scary”Christ said. “Because what we found means the ice cap has melted and raised sea level in a climate system like ours. This, as a climatologist, is more serious ”.

Further studies are needed to reduce the period of time over which this merger could have occurred, Christ said. This likely occurred during a period of relative warmth known as the “interglacial”. The ice layer would have slowly diminished, like an ice cube moved from the freezer to the refrigerator.

The current cast in Greenland is more like an ice cube moved from the freezer to the oven. And humans keep raising the temperature of the oven.

The entire Greenland ice sheet is unlikely to collapse in the foreseeable future.

“But if we heat the ice cap to more than 1.5 degrees Celsius,” a number of United Nations scientists have identified as the threshold for catastrophic climate change, “the risk of complete elimination increases more and more “, did he declare. an ice expert from the University of California at Irvine, who was not involved in the new study.

The fact that this has happened from natural causes in the past is no consolation, he added. Geological records show the cost of past climate change to animals and ecosystems, and offer a warning of what humanity may face.

Unless the world drastically cuts its greenhouse gas emissions, scientists predict Greenland could lose up to 35.9 billion tonnes of ice over the rest of the century. The subsequent rise in sea level could exceed three feet (almost one meter), which would significantly worsen hurricanes and flooding.

Christ tried to imagine what must have crossed the minds of the men who obtained these samples in the 1960s. The notion of artificial warming hardly existed. People were much more concerned about the looming threat of nuclear war.

And yet, “even at this point in history, we had already pushed Earth’s climate system into uncharted territory,” Christ said.

The discoveries offer a kind of poetic justiceHe continued: Over 60 years ago the Americans went to Greenland believing they could conquer the ice. But they left with a hard lesson on the fragility of humanity.

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