This past summer, I was leaning on a metal railing on the walkway near the famous surf spot known as Steamer Lane in Santa Cruz, California. From the cliffs, I was looking down at the surf as it ran ashore and twisted into consistent swirling patterns. The waves rushed up against the cliff edge, then rebounded back onto themselves as they swirled atop the sand before dissipating. “It’s all a matter of numbers and time,” I thought to myself, as I imagined small grains of soil slowly being carved out of the coastal edge. These places appear to be stable, reliable entities—they are not. For many of the world’s coastal residents, this is an unsettling reality. Sea levels are rising, and humanity’s response is often defensive: sea walls, riprap, and so on. Given that we seek stability, whether imagined or manufactured, what can be done about the incessant, incremental threat of rising seas? Here anthropology, with a little imaginative push from speculative fiction, can help us grapple with humanity’s future on the edge of the sea.

Past

Humans have occupied Isla de Cedros in Baja California, Mexico for about twelve thousand years. The settlement of Isla de Cedros was part of a broader pattern of migration near the end of the Pleistocene, in which humans followed a coastal route (see Erlandson et al. 2007). This island, which has some of the oldest shell middens along the coast of North America, was first occupied either right before or just after changing sea levels separated it from the mainland. Between 13,000 and 7,500 years ago, the Isla Cedros coastline changed dramatically. The first human occupants of this island, Matthew Des Lauriers (2006, 264) argues, likely arrived with extensive knowledge of marine resources and how to exploit them.

Maps of Isla de Cedros’s shoreline during the Pleistocene-to-Holocene transition show the striking changes that took place over this 5,500-year period. Anyone who has spent extensive time in coastal spaces knows that relatively subtle changes in tides and shorelines can have dramatic effects. People who live along the coast must have extensive knowledge of all of these factors and conditions. This knowledge is a matter of hours and days, but also seasons and years. Maps of Isla de Cedros’s changing coast push me to think about all of the knowledge that people carried with them, and also how that knowledge had to be adapted over time when once reliable sites were slowly inundated. The capacity for adjustment is crucial. Still, it’s important not to see the past as merely a collection of adaptive success stories. Some people didn’t survive these changes, and survival is never just a matter of ingenuity.

Present

One day in March of 2012, while doing my fieldwork in the Cape Region of Baja California Sur, Mexico, I was mapping the tide line of a large sandy beach with a GPS device. Early one morning a week later, I heard that this beach had collapsed. I drove over to check it out. Indeed, about twenty meters of this large sandy beach had rapidly fallen into a deep underwater canyon. I remapped the tide line that day, struck by the instability of it all. Gone. Later that morning I talked with a fisherman who has known this place for decades. Oh, we’ve seen this before, he said nonchalantly. The same exact thing happened about forty years ago. The evidence is there, but unless you witness striking events or have this kind of specific, place-based knowledge, it’s easy to miss. It’s all too easy to slip back into the comforting illusion of stability.

Perhaps the Holocene has been too easy on us. Between eighteen and seven thousand years ago, rapid global warming resulted in tremendous rates of sea level rise. As Gary Griggs (2017, 4) explains, “sea level rose on average nearly half an inch per year or about forty-five inches per century.” Depending on the coastal topography, this could have translated to dramatic changes in shorelines. For about eleven thousand years, the global coast was incredibly volatile; humanity had to adjust. For the past seven thousand years, global climate and sea level rise have remained relatively stable. This has resulted in a tremendous expansion of human populations along the world’s coasts. Today, approximately three billion people live between 60 and 125 miles of the coast (Griggs 2017, 11). With the onset of sea level rise in the twenty-first century, humanity is once again entering a more volatile relationship with the edge of the sea. Adieu, complacency.

Future

“The act of imagining diverse futures,” writes Andrew Merrie, “can reveal unseen pathways and can inspire human ingenuity, while also highlighting the limitations of human agency in a complex world.” Kim Stanley Robinson’s Three Californias trilogy, written in the 1980s and 1990s, envisions three different futures for one of the world’s iconic coastal territories. In this series, California’s possible futures are imagined as apocalyptic, dystopian, and utopian respectively. But it was not until his New York 2140, written in 2017, that Robinson directly tackled the question of sea level rise. Robinson describes it as a book about coping: “What I want to explore is the idea that the coming crisis will force us to invent a kind of postcapitalism, but that global capitalism will not let go of our social systems easily. It’s entrenched, it’s defensive, and it’s incredibly powerful.”

It is, moreover, about numbers and time. We have the incremental threat of sea level rise crashing, inevitably, up against growing coastal populations and deeply ingrained economic systems. Numbers coupled with ideologies and habits. So where to now? We likely can’t count on the luck of late Pleistocene stability to save us this time. Climate change and sea level rise are not the problems per se; rather, our quandary lies in thinking that is bound up with assumptions of, and perhaps hopes for, stability. Can we look back and then forward—with the help of speculative fiction—to see our way through this anthropogenic bind?