Climate change is putting pressure on one of science’s earliest fields of discovery: archaeology.

Drought in the Colorado River Basin is once again exposing age-old artifacts as lakes and rivers turn into mudflats. And where droughts do not occur, there are floods – sometimes in quick succession with drought.

Consider the Mississippi River Basin. Two and a half years ago, the basin experienced record flooding that devastated the riverbanks and adjacent land filled with artifacts dating back to the Mississippian civilization. Today, the river is so dry that shipwrecks rise from watery graves, including in the Lower Mississippi, where Spanish conquistadors arrived in the 16th century, followed by French explorers who sailed the river as they claimed the region for King Louis XIV, calling it “Louisiana.

“The pattern seems to be that we swing wildly from one spectrum to the other. In the long run, it’s not good for archaeology,” said Charles McGimsey, an archaeologist from Louisiana. “Archaeological sites do best either staying under water or staying on dry land. Going back and forth is not good.”

Yet as more artifacts emerge — from Mesopotamia to Mississippi — scientists say drought and other impacts of climate change are undermining their ability to protect and document important sites before they degrade or disappear.

Record floods in the Nile River Basin in 2020 came perilously close to damaging Al Bajrawiyya in Sudan, the heart of the ancient Kingdom of Kush and a UN World Heritage Site. according to reports from Agence France Presse.

In Iraq, ancient structures, including Babylon, the capital of two Babylonian empires, began to erode as salt concentrations associated with the drying of riverbeds and eventual saltwater intrusion began to erode their clay foundations. as reported from guard.

In August, as extreme drought gripped Europe, a flotilla of World War II-era German warships sunk in the Danube River in Serbia emerged from the water. In central Spain, receding water in the Valdecanas Reservoir has revealed Bronze Age granite boulders known as the Guadalperal Dolmens. According to Reuters news service.

Climate risks to cultural artifacts are also a growing concern in the United States, as more sites are damaged by extreme weather conditions, both inland and along the coast.

“Of course, all archaeologists are concerned about the effects of climate,” said Tim Paukettat, a professor of anthropology at the University of Illinois Champaign-Urbana and Illinois state archaeologist.

Pauketat, who has studied what is believed to be one of the most intact pre-European settlements in North America at Cahokia near modern-day St. Louis, said climate change has accelerated long-standing fears among archaeologists that many of the undiscovered historic and prehistoric sites in the world, objects disappear one fossil at a time, a primitive tool or a piece of pottery.

The National Park Service, which manages 85 million acres of culturally or naturally significant areas, has cataloged nearly 150,000 archaeological sites. The agency has a dedicated archaeologist in its climate change response program to coordinate staff and research on topics that “range from coastal erosion and storm damage to the effects of wildfires, floods, melting permafrost and degradation due to changing are rain and temperature patterns,” officials said.

The Bureau of Land Management—although less directly involved in archaeological surveys—issues cultural resource permits that allow individuals or organizations to conduct field research on BLM lands. The agency has also strengthened its climate commitments, noting on its website that its mission of multiple uses for BLM conservation, recreation and commercial use is directly threatened by climate change.

Dave Conlin, an archaeologist and head of the Colorado National Park Submerged Resources Center, said exposing cultural artifacts due to climate change — especially in aquatic conditions — is harmful for two reasons.

“The first is that they experience a wet-dry cycle,” which makes preserved objects brittle, a problem compounded by waves and changes in hot and cold surface air temperatures. The other is exposure to people who are invariably drawn to curious objects sticking out of a riverbank or rising above the water’s surface, he said.

“For terrestrial sites, seeing them can involve an extensive hike into the countryside, where things are more hidden and can be more difficult to access,” Conlin added. While archaeological sites in dried up lakes and rivers “can be easily accessed by people on a pontoon boat.”

The two huge reservoirs of the Colorado River Basin, Lake Powell and Lake Mead, offer excellent examples of what happens when extreme drought occurs and lakes whose combined normal surface area covers 500 square miles effectively shrink. The shoreline widens, lakeside marinas become dry docks, and the “bathtub ring” lining the edges of the reservoirs marks the top of canyon-like walls.

Last summer, experts said Lake Mead had dropped to its lowest level since 1937. Today, the drought-stricken reservoir has revealed numerous artifacts, including the remains of a 19th-century Mormon settlement called St. Thomas, which is now open to visitors at Lake Mead National Recreation Area.

Lake boats also appear. Earlier this year, Higgins landing craft like those used by US and Allied forces storming France’s Normandy Beach on D-Day floated ashore on the reservoir. Experts say it was used as a research vessel during the filling of the reservoir. Before the landfall, the landing craft was about 185 feet below the surface of the lake.

McGimsey, the Louisiana state archaeologist who recently examined the find of a late 19th-century river ferry near the east bank of the Mississippi River in Baton Rouge, said the vessel, while not as old as other shipwrecks in the canal, represents a unique era in Louisiana history when the river was still primarily used for agriculture and transportation.

Due to its proximity to the dike, locals and tourists are allowed to approach and even touch the remains, something that would not be allowed under other circumstances.

“There are records that show literally hundreds of ships sunk in the Mississippi during Europe,” McGimsey said. “I certainly expect more to emerge if the river continues to drop, and we’ll do our best to get out there and record them.”

Reprinted from E&E news with permission from POLITICO, LLC. Copyright 2022. E&E News provides important news for energy and environmental professionals.

https://www.scientificamerican.com/article/climate-change-is-adding-urgency-to-archaeology/

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