As sea levels rise due to global warming, thousands of archaeological sites in coastal regions around the world could be lost due to erosion, a team of archaeologists have warned based on the findings of a recent study.
Torben Rick from the Smithsonian Institution, Leslie Reeder of Southern Methodist University, and Jon Erlandson of the University of Oregon have issued a call to action for scientists to assess the sites most at risk in a paper published in the latest edition of the Journal of Coastal Conservation.
The archaeologists modelled the impact of coastal erosion and urban expansion on archaeological sites, and presented a case study from southern California’s Santa Barbara Channel region (SBC), including the Northern Channel Islands. Their focus was understanding the effects and future impacts of sea level rise, marine erosion, climate change, and modern development on the preservation of archaeological records.
The researchers rued the fact that outside of the archaeological community, the conservation of global cultural heritage and the archaeological record rarely receive mention, let alone priority. "The vast majority of the human past is known only from the archaeological record—a fragile resource that greatly enhances our understanding of human behaviour, diversity, and ecology. Unfortunately, the archaeological record is non-renewable and heavily threatened by modern human development and natural processes like stream and coastal erosion," they wrote. The researchers called for destructive threats to archaeological records to be quantified and systematically examined so informed decisions can be made about preservation and efficient mitigation.
The Santa Barbara Channel region has one of the longest known occupations of any coastline in the Americas, dating at least 13,000 years ago. When Europeans first arrived, the Chumash peoples living in the area had some of the highest population densities of hunter-gatherers in the world. The researchers say that the early occupation of the SBC is important for understanding the initial peopling of the Americas. Recent evidence has showed that rising sea levels about 15,000—7,000 years ago submerged much of the archaeological evidence. Today, thousands of archaeological sites on the shorelines and sea cliffs of the SBC are once again threatened by a number of social and environmental factors. The reasons, the scientists say, are modern urban development, sea level rise, and global warming.
The archaeologists worked on the coastal vulnerability index (CVI) developed by the United States Geological Survey based on quantifiable data like geomorphology, historical rates of shoreline change, coastal slope, relative sea level rise, wave action, and tidal range. They then proposed developing an index of the sites most at risk so informed decisions can be made about how to preserve or salvage them. They have called it the cultural resource vulnerability index (CRVI).
The team used this index foe their pilot study and found that of the 2,328 archaeological sites in the SBC coastal zone, 57 scored “very high” on the CRVI. These most threatened sites were primarily found within 100 m of the shore and below 30 m in elevation. Another 270 sites had a “high” score.
They pointed out that 150 known archaeological sites were located at less than 2 m in elevation. "If the MSL rises one metre during the 21st century, and if the tidal range remains steady at around 1 m, these sites would likely be inundated or severely eroded. Only 350 known sites are currently located on private land, while only 220 known sites are expected to be on urban land by 2050," the archaeologists warned.
