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The 5,000-year-old answer to surviving rising seas

One anthropologist’s research in Puerto Rico is needed more than ever — and threatened like never before

By Eric Niiler

For decades, anthropologist Isabel Rivera-Collazo has been telling a narrative about climate change through her research, showing how ancient populations adapted to environmental pressures.

When Hurricane Maria devastated Puerto Rico, Rivera-Collazo suddenly found herself a character in that story.

The night the hurricane hit in September 2017, Rivera-Collazo, a professor at the University of California San Diego and the Scripps Institution of Oceanography, was at home in California, talking to her Puerto Rican family by phone. Her relatives were hunkered down in their house, high in the mountain village of Aibonito in central Puerto Rico. At some point, nearby cell towers went down and she lost contact with her mother-in-law.

Her relatives all survived. But the hurricane eventually claimed nearly 3,000 lives — including many people Rivera-Collazo knows through family and friends. It wiped out thousands of the island’s homes, schools, and hospitals. And it began a speedy process of wiping away the core of her scientific work: a string of archaeological sites along the Puerto Rican coast.

Now, Rivera-Collazo, 43, has been immersed, not only in reclaiming those sites, but in applying her academic research to questions that are critical today. From communities that lived millennia ago, she says, we can draw lessons not only about where to rebuild present-day communities, but also how to protect them.

“Because we have at least 5,000 years of the decision-making on this landscape,” she says, “we can use that locally relevant knowledge to inform the present.”

Rivera-Collazo grew up in Puerto Rico. After studying anthropology and archaeology at the University of Puerto Rico, she worked on archaeological sites in Israel and the Middle East, then completed a PhD in environmental archaeology at University College London.

She returned to Puerto Rico to do much of her field work, tracing settlements from 5,000 years ago to the arrival of Spanish explorer Ponce de Leon and colonial rule.

The indigenous people who lived on the coastal plains of Puerto Rico, she says, knew not to build their villages beyond the protective sand dunes and swampy wetlands that act as a buffer against storms. (It’s a lesson that resort developers along the coastline have mostly forgotten.) These former inhabitants of the island, known as the Boricua, also brought with them sustainable crops from other Caribbean islands that could withstand long droughts or periods of intense rainfall and flooding such as the “Medieval Warm Period” that lasted from 900 AD to 1300 AD.

“I am acknowledging that we are facing a dire scenario. I want to see what works instead of what fails.”

Modern Puerto Rico, by contrast, relies heavily on imported food — 85 percent of the island’s diet comes from elsewhere. While tending a backyard farm might not work for San Juan’s urban residents, Rivera-Collazo says, it could have made a huge difference for the vast rural areas that suffered for months after Maria knocked out electricity, roads, and water supplies. Rivera-Collazo has found evidence of this ancient food resiliency in some of her study sites in south central Puerto Rico. 

Though previous cultures grappled with temporary changes in the climate, Rivera-Collazo says Maria is a sign of something more dire: global temperature changes that are driven by human activity, and affecting the island at a rapid pace. In the past year, many of the archaeological sites that Rivera-Collazo has been studying have been wiped away by flooding and sea level rise. In early 2018, unusual tidal floods ate away 6 feet of dunes where she and her students have been digging for clues to past villages. Some of these artifacts and stone homes now lie underwater, like Atlantean villages just off the Puerto Rican coast.

Flood waters surround homes in Catano, Puerto Rico, one week after the passage of Hurricane Maria in 2017. Photo by Carlos Giusti/AP

In a research study published in 2018, Rivera-Collazo and her colleagues found 27 archaeological sites in Puerto Rico that flood at high tide, another 56 that will flood by 2050, and 140 sites that will flood by 2100 — all the result of sea level rise that could reach nearly 6 feet by the end of the century.

“What I’ve seen in the last two years, I’ve never seen before,” said Rivera-Collazo. “Sites are literally disappearing one day after the next.”

And as Puerto Rico continues to rebuild, she says, the work of restoring those sites feels even more pressing. “Some archaeologists want to look for collapse, but I want to look for continuation and what elements of a society made them resilient to changes,” she says. “I am acknowledging that we are facing a dire scenario. I want to see what works instead of what fails.”

Even before Maria struck, Rivera-Collazo’s scientific drive had merged with her personal connection to the island. In 2013, she received a National Science Foundation grant to set up an outdoor museum called Hacienda La Esperanza in the town of Manatí. The project pairs archaeology and environmental studies students from the University of Puerto Rico with citizen-scientists from the local community to teach visitors about the region’s history, archaeology, and ecology, says Carlos Torres, an agronomer and ecologist for Puerto Rico’s largest conservation group, Para La Naturaleza.

Torrez, who also worked on the Hacienda project, says Rivera-Collazo has made a huge difference in protecting the island’s cultural heritage by getting local residents to care about it.

“She’s one of the few people in Puerto Rico that are protecting this information and archaeological sites…for younger generations,” Torres says. “She was one of the scientists that really liked to work with people that didn’t have a scientific background. She takes time to explain science to people.”

In the months after Maria, Rivera-Collazo grew even more involved; she put down her laptop and picked up a clipboard, organizing relief shipments of solar panels and water filtration from systems from the San Diego area to help families without power or water.

“When I was responding to Hurricane Maria, people said I was taking it too personally,” says Rivera-Collazo. “Many scientists do not work at their own sites, so when disasters occur, they stay back and they are safe. But when you are embedded into your own community, for me it is more important to do science for my island than for other people.”

Now, Rivera-Collazo is a member of the Puerto Rico Climate Change Council, a group of scientists and academic experts that is advising the government on future scenarios. Emergency officials want to relocate residents away from the coastline because of risks of flooding and future storms, she says — something that, historically, has been easier said than done.

“The one thing I have learned, based on research of thousands of years, is that people do not move easily, even if they know there is a threat,” Rivera-Collazo says. She hopes her data might convince the public that relocation is the best solution, and that relying on technological fixes, such building concrete sea walls or putting houses on stilts, probably won’t work in the long term.

This summer, Rivera-Collazo will return to Puerto Rico with her students to help rebuild a dune ecosystem that was washed away earlier this year, along with evidence of past cultures and how they handled changes in their era.

She’ll also urge policymakers to remember the lessons that she has uncovered — the biggest one being that we shouldn’t rely on modern technology to save us from climate change.

“People have trusted technology because we thought that we could predict, respond to, and stop these changes. But the reliance on technology was so large with Maria that it caused a catastrophe,” she says. “We need to understand how people recovered from these [environmental] changes in the past. We do not have the luxury of trial and error.”

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Eric Niiler is a writer based in Washington, D.C.


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