A dog is seen through the large gaps in a barbed-wire fence, from which hangs a yellow and red radiation warning sign.

How do we warn future generations to avoid our buried nuclear waste?

Fearsome monuments, color-changing cats, and atomic "priesthoods" have all been proposed as solutions—but warning humanity of this existential danger is much harder than it sounds.

A battered placard warns of radiation inside the Chernobyl Exclusion Zone in Buryakovka, Ukraine, 2011. Research suggests that as little as 6% of the world’s population recognizes the “universal” radiation warning sign of a trefoil against a yellow background.
Photograph by GERD LUDWIG, Nat Geo Image Collection

For around five decades, human beings have been burying nuclear waste deep underground—a radioactive legacy that may remain lethal for thousands of years. But with more than 20 nuclear repositories in consideration and development across the world, how will our descendants some 500 generations from now be able to identify where and what these sites are, and why they should avoid them? The problem has been tackled with proposals ranging from ominous monuments and “atomic priesthoods” to glowing cats, but it turns out that warning future humans of danger is much harder than it sounds.

For centuries in northeast Japan, for example, people have erected enormous stone tablets along the coast to warn future generations of tsunami threat. Despite declaring that nothing should be built below a certain point, many later residents ignored or forgot the warnings and built homes in vulnerable areas, paying a terrible price. More recently, the U.S. government standardized a universal warning sign for radiation in the 1950s (a trefoil of black blades on a yellow background)—but research suggests that as little as 6% of the world’s population may actually recognize it.

The ‘abyss of deep time’

In the early 1980s, as world governments and the nuclear industry became increasingly concerned about what to do about the long-term storage of radioactive waste, a new field of study developed: nuclear semiotics, the very broad, esoteric, and sometimes surreal study of how we will warn future humans, civilizations—or even post-human species—about our deadly legacy.

The creation of nuclear semiotics is credited to a group of engineers, scientists, political scientists, psychologists, anthropologists, archaeologists, and more who worked on the Human Interference Task Force (HITF).  Formed by the U.S. Department of Energy and Bechtel Corp. in 1981, the task force took their cues from the monumental structures, sacred texts, and even curses that survive from ancient civilizations in order to come up with our society’s “largest conscious attempt to communicate across the abyss of deep time.”

The HITF decided that the most effective way to scare future generations was through the creation of enormous monuments around nuclear-waste storage sites that were designed to evoke a sense of danger and dread. One proposed “stop sign” is a sprawling landscape of huge rock-like thorns emerging from the earth in every direction, while another suggests a sort of atomic “Stonehenge” over the waste repository, comprised of huge granite columns marking its boundary, earthen ramparts round the facility’s actual footprint, and a structure at its heart containing information about the site. Additional copies of the information would be buried around the site self, and in stored archives around the world on special long-lasting paper, labeled with the perhaps optimistic administrative message: “Keep for 10,000 years.”

Even with equally chilling warning messages that could be carved into such creations (one example: “This place is not a place of honor. No highly esteemed dead is commemorated here… nothing valued is here. What is here was dangerous and repulsive to us.”), monuments on such a scale are more likely than not to attract attention from the curious, the criminal, and even future archaeologists, and end up encouraging the very thing that they are supposed to prevent—the excavation of the site. The Egyptian pyramids are a case in point. They are still here, but the priests are long gone, and we ignore the terrible curses, looting their burial chambers and desecrating their dead.

Ironically, one of the most pilloried proposals made to the HITF was that of a self-perpetuating, manipulative “atomic priesthood” with a designated elite who would employ myth, legend, and secretive ritual to create a sense of taboo around these sites for generations to come.

The HITF ended their work in 1984, concluding that any successful attempt to communicate a warning across deep time will have to rely on monumental architecture and markers. Structures should be durable enough to require no maintenance for 10,000 years, and should be disturbing enough to inspire people to transmit knowledge about them—whether through oral legends or physical archives—across countless generations.

‘Furry Geiger counters’

A few years after the HITF was formed, writer Françoise Bastide and semiotician Paolo Fabbri came up with a very different approach to keep future generations from our buried nuclear waste: the Ray Cat. In the future, they believed, cats could be bred to change color in the presence of radiation. The cats would then be released into the wild, and while generations of Ray Cats prowled the land, the story of the color-shifting felines and the danger they represent would be passed down to future human generations in folk tales and oral histories. 

Ray Cats were thought to work better than, say, Ray Dogs or Ray Rats because of the supernatural associations humans have fairly consistently attached to cats across many cultures: The ancient Egyptians worshiped the cat god Bastet, the Vikings believed that two cats propelled the chariot of the goddess Freya, and in China, farmers worshipped the cat deity Li Shou who protected crops from rats and drove away evil spirits. The cat is also synonymous with independence and the freedom to go wherever it wants, which is useful for a furry, mobile Geiger counter.

“Looking at it through a scientific lens, a Ray Cat doesn’t look too crazy to me,” says Kevin Chen, founder of Ray Cat Solution in 2015, a community of people who are fascinated by Bastide’s and Fabbri’s ideas and exploring the possibility of genetically engineering felines to glow through enzyme interaction. “I mean it’s crazy, but as crazy as the idea of bringing back the woolly mammoth. The concept is there, the technology doesn’t necessarily exist today to do it, but along the way we will figure out how to do it and may gain other benefits from it.” 

The Ray Cat has certainly inspired storytellers, visionaries, and artists to join Chen’s embryonic movement with Ray-Cat reverent t-shirts, songs, music videos, and even an award-winning documentary, The Ray Cat Solution. Such cultural products help insert these four-legged warning signs into the popular imagination and build the legend, much as its creators intended—and, perhaps, help to trigger the research needed to start the long process of turning Ray Cats from concept into reality.

Parchment, not priesthoods

Forty years after the HITF, the Paris-based Nuclear Energy Agency, an intergovernmental agency that encourages cooperation among 33 advanced nuclear countries, was still coming up with ways to warn future humans about breaking into toxic radioactive mausoleums. Its Preservation of Records, Knowledge and Memory Across Generations (RK&M) initiative published its final report in 2019, just as governments were reconsidering nuclear energy as a step in reducing global warming.

Unlike the atomic “priesthoods” and “Stonehenges” of decades ago, the RK&M report focuses on ways to help future humans make informed decisions through the use of libraries, time capsules, and physical markers. Rather than a field of enormous rock thorns, for instance, thousands of markers could be buried around a nuclear waste site, possibly containing information that’s recorded on durable materials like vellum (parchment made of animal skin), rather than on laminated paper documents or USB drives.

“I think that there has been a change in perspective over the last 40 years,” says Neil Hyatt, chief scientific adviser to the U.K. government’s Nuclear Waste Services. “Now the international community has moved on…to think about a multi-layering of messages using different tools to pass on information about what was done on these sites, to allow people to make up their own mind about how they might interact with it in the future.”

Hyatt believes this approach is reflected in the British plans to find a willing community to house its national nuclear repository on British soil, cultivating the community relationship not just during site construction, but all the way through the 750 planned years of its operation, closure, and post-closure monitoring under institutional control.

In her work, artist and researcher Cécile Massart embodies this new approach. She imagines creative laboratories built above future nuclear waste repositories, where writer-explorers, artist-guardians, and scientist-archaeologists could work together to monitor the sites over many generations. “The geological repositories themselves become platforms for artistic research and landscape design,” Massart says.

Ultimately, the millennia of deep time dwarfs any human timeline. “It’s hugely interesting and challenging as a technical person to be talking about this, because it takes us right to the core of what it means to be human,” says Hyatt. “The good news is that we’ve got a long time in front of us to find the essential solutions.”

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