Researching Climate Change in Puerto Rico at the Scripps Center for Marine Archaeology

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A report by Will Bowen for La Jolla Light.

Although many people are in disbelief and so they are complacent, scientists have been warning us that the Earth is undergoing global climate change and we must prepare for it if we are to have a productive future. The theory is that global conditions have been warming up as part of a natural cycle since the last Ice Age (Glacial Maxim 20,000-25,000 years ago), but in the last few decades things have dramatically sped up due to human activities.

The intense burning of fossil fuels has caused a steep rise in the levels of carbon dioxide (CO2) in the atmosphere, creating a greenhouse-like effect and leading to hotter conditions that have begun to rapidly melt ice in glaciers and at the polar caps, thus causing the oceans to rise.

For millions of years, the level of CO2 in the atmosphere has paralleled air temperature. Scientists think that temperature will inevitable rise to match the radical spike in CO2 level, though it hasn’t yet.

If you look at aerial photographs of the major glaciers or study maps of the Arctic and Antarctica you can see the effects of global warming boldly demonstrated. Glaciers have shrunk and large areas of the polar ice sheaths have melted.

It is not certain what Mother Nature will do. Humans can only guess at the future based on the data and the models we have. But it looks like we will eventually lose low-lying places on the ocean front, for example, the beautiful city of Venice, Italy. It’s also thought that San Francisco Airport may be underwater in 100 years, unless some sort of sea wall is built to protect it.

Many of our California beaches (worth about $60 billion a year in tourist revenue) may also end up under water.

Finding a link to past rising seas

What can we do about climate change? Can we stop it or alter its course? Some scientists think we still have time, others say it is far too late and we will just have to adapt by moving back from the coast as the oceans rise. We are not unique in the dilemma we face. In past times, other human beings faced the same problem of rising oceans. Throughout the world there are civilizations now underwater, lost to the rising oceans.

In La Jolla, there is evidence offshore and underwater that two Native civilizations (flourishing 8,000 and 12,000 years ago) experienced serious sea-level changes that impacted their lifestyle and led to their disappearance. Hopefully, we can learn from these lost cultures by studying and understanding how they adapted or failed to adapt to climate change and rising seas.

Scripps Center for Marine Archaeology

Scripps Institute of Oceanography (SIO) is resolute on the idea of learning from the past. Its researchers have started a project to study the past, called the Scripps Center for Marine Archaeology (SCMA). The goal of SCMA, which is a team effort by SIO and the UC San Diego Department of Anthropology, is to investigate the influence of changing marine environments on ancient societies and to reconstruct archeological sites that are now under the water.

SCMA was founded by SIO emeritus professor Walter Munk and Damien Leloup, who met at the world renowned Explorer’s Club. Leloup used to dive with the great French oceanographer and inventor of the aqua lung, Jacques Cousteau. Together Munk and Leloup were able to raise $400,000 to start SCMA.

The Center is currently headed by UCSD anthropology professor Tom Levy, an archaeologist who specializes in the Middle East, and John Hildebrand, a professor at SIO known for his work using sound for underwater sensing and discovery. The purpose of SCMA, according to Scripps’ director Margaret Leinen, “Is to advance marine archaeology as a field, and on a larger scale, to help scientists explore ways to better understand and protect our planet.”

Carol Padden, dean of UCSD Division of Social Sciences, added that SCMA will, “Find ways to study the relationship between society and the sea, increasing our knowledge of the past for a better future.”

Said Levy, “We are not just going to study sunken ships, but we will look at the adaptation of coastal societies who underwent environmental change. There are hidden coastlines now underwater all over the world where civilization and culture once flourished. Those are the places we need to study.”

Adding new expertise

SIO and the anthropology department jointly hired two new faculty members who’ve been studying climate change as the first step to grow SCMA. These new professors are Isabel Rivera-Collazo, who specializes in human resilience and adaptation to climate change on the island of Puerto Rico; and Jade d’Alpoim Guedes, a Harvard graduate who works on climate change in Tibet and China.

Rivera-Collazo said she grew up on a small farm in the mountains above San Juan, Puerto Rico, where her family grew vegetables and herbs. “I ran all around the wilds of the mountain. We were like hermits. People would say, ‘Oh, look at those hippies!’ ” she laughed.

The people who supplied her family with irrigation equipment spoke Hebrew. Because she liked the sound of their language, when the opportunity came up, she went to Israel for the summer to study Hebrew and live on a kibbutz. “When I was in Israel, I discovered archaeology. There are so many treasures of the past in the Holy Land. So when I went back to school in Puerto Rico, I changed my major to archaeology. I later returned to Haifa to study underwater archaeology,” Rivera-Collazo said.

She studies the Late Pleistocene and Holocene eras when modern man first arose. She has found habitation sites off the coast of Puerto Rico from the time when the oceans were much lower. “The last Glacial Maxim was 25,000 years ago. Since then, the planet has been warming steadily. But here were two periods when the rapid melting of ice stopped for several thousand years … long enough for coastal civilizations to develop. These two periods of stability of the ocean level are called the Younger Dryas and the Bolling Allerod,” Rivera-Collazo explained.

These stable periods can also be observed off the coast of La Jolla at depths of 24 meters (78 feet) and 59 (193 feet) meters. At these depths, underwater archaeologists have found evidence of Native civilizations.

In 1964, more than 100 Native American stone bowls were brought up by SIO divers. It is predicted that a more thorough study of sites at these depths will reveal human presence dating back 8,000-14,000 years. These will undoubtedly be the oldest sites in San Diego, where almost all inland archaeological sites are younger than 7,000 years.

Rivera-Collazo will be joined by Guedes, who graduated with a Ph.D. from Harvard University in 2013. Like her colleague, Guedes grew up on a farm where she helped her father collect seeds in Portugal. Guedes said she has been studying climate change and adaptation along the coast in China and in Tibet, and like Rivera-Collazo, she is very interested in making archaeology relevant and useful for modern times.

One of the amazing applications of Guedes’ work is the recommendation she made to introduce Hopi Indian corn to Ethiopia where it is getting too hot and too dry to grow its staple crop of bananas. She has further recommended the return to the farming older grains, which were once staples on the Tibetan plateau in the days when Tibet was a warmer land, like it is now becoming again.

Of our impending local problems with the sea, Guedes said, “It is essential to understand how humans from the deep past of La Jolla dealt with challenges, such as a rising sea level and a changing coastline, and to highlight the similarities and differences to what our town faces today, so that we can take the best path forward in protecting this beautiful place.”

With such a great staff, Hildebrand is confident that SCMA has a rosy future. “We want to have a lot of public participation in our work, and that will include seminars and workshops for people to come and get involved. We are also going to have a field school where people can learn underwater archaeology, both in Israel and right here in La Jolla!” he said.

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