The effects of climate change are not only threatening fragile ecosystems, but could erase our past as well.
Cliff palaces in Mesa Verde National Park. Image by Ken Lund via Flickr
In the hot middle of August 1996, lightning struck a dense piñon-juniper range in Mesa Verde National Park, Colorado. Then flames licked up, burning northward through Soda Canyon, Little Soda Canyon, and Park Mesa’s research area. The blaze ran its course for seven days. Aircrafts doused the park in water, and fire retardants known as “slurry” were used to snub out flames in the nooks of tough-to-reach craggy topography. Slurry stains are still visible, almost 20 years later, on the impressionable sandstone trail to Spruce Tree House, a collection of cliff dwellings. The national park contains an estimated 600 buildings fashioned into cliff alcoves, and over 5,000 other archeological sites produced by the Ancestral Puebloans. Although the fire quit just before reaching the Visitors’ Center, burning through a small (but important) 4,781 acres in the end, it accelerated a natural process known as spalling. When water evaporates in sandstone, layers of rock flake off. Because of this accelerated spalling, the fire claimed an important victim—the famous Battleship Rock Panel, which was degraded and destroyed. This petroglyph panel portrayed humans and animals, dated roughly back to 1100 AD, was chiseled into the sandstone, and helped archaeologists contextualize life of the Ancestral Puebloans.
The tremendous loss of a pivotal archaeological site as a result of the fire not only substantially changed how park archaeologists treat post-fire sites, but also offered a revealing glimpse of what’s to come as the effects of climate change take hold over the next century. A 2014 report by the Union of Concerned Scientists featured Mesa Verde alongside 29 other national landmarks that are now at risk because of the effects of climate change. Researchers say climate change will make longer and hotter fire seasons, and the resultant fires could potentially devastate archaeological preserves like the one at Mesa Verde. The report notes that over the last 600 years in that region, the last 50 have been the hottest. But it’s not just Mesa Verde, or even the United States. Climate change threatens to erase archaeological sites across the world.
Degrading Chilean Mummy. Image by Vivien Standen via Nature World News
Examples are abundant. In Peru, the intricate designs of the 600-year-old city of Chan Chan are suffering from increased torrential downpours due to overly abundant El Nino patterns. UNESCO described the erosion as “rapid and seemingly unstoppable.” Ironically, many of the same processes that put these sites at risk also turn up new artifacts. By 2007, over half of the acres in Mesa Verde had burned since the fire, revealing 676 new sites previously hidden beneath vegetation. The same ecological complications that are turning frozen Chilean mummies into black ooze are also causing artifacts and bodies to emerge from receding glaciers.
Maria Caffrey, a paleo-climatologist and research associate at the University of Colorado, Boulder was hired by the National Parks Service (NPS) to study how climate change will affect sea-level rises and storm surges along 118 costal park sites. Many archaeological sites occur along coastlines, where humans settled near the water. “As the climate gets warmer, we’re estimating storms will get more intense,” Caffrey tells me.
Uncovered Yup'ik artifacts. Image via Twitter user @adndotcom
Along the northwest coast of Alaska, for example, these bigger storms, along with erosion and rising tides, threaten to sweep away 1,000-year-old artifacts and sites of the first people to live in that area. One site along the Bering Sea contains a Yup’ik village frozen in thick layers of permafrost. It now faces the threat of melting, exposing the delicately preserved village to the elements—a 30-foot area at the edge of the site has already been washed into the sea. And it’s not just the ancient past that’s under threat. Jamestown, Virginia, part of Colonial National Historical Park, faces a massive threat from rising tides and rising water levels that might flood buried artifacts.
“Do we take them out and risk exposing them to the air, and potentially see more damage that way, or do we leave them in place?” Caffrey asks.
Cape Hatteras Lighthouse. Image by Gilz via Wikimedia Commons
These questions—whether and how to save which sites—will become increasingly important as climate patterns shift, and archaeological sites begin to take the brunt of the climate blow. Even if we could figure out the exact impact of change for every important site, the nature of choosing what to protect—and how to do it—might be more of an engineering and economic problem than a scientific one. In 1999, the NPS decided to move the Cape Hatteras Lighthouse 1500 feet from the shoreline, at a cost of $11.8 million. “The decision to relocate the Cape Hatteras Light Station was a sound public policy decision based on the best science and engineering information available,” the NPS writes. It’s not clear how many lighthouses will fall into a rising sea, but it’s unlikely we can move every single structure, let alone every broader archaeological site, that is at risk.
“This is the legacy we’re leaving for future generations,” Caffrey said. “We’re going to have to ask the tricky questions, of what ones do we try to save, or if we don’t save any at all, or whether or not some of these things eventually become monuments to climate change. Instead of having a lighthouse you can walk up to, maybe it becomes a submerged site that you can take a snorkel tour around and learn about climate change that way.”