By Mike Toner
Washington State Division of Archaeology staff Maegan Smith and Chip McGimsey, Ph.D., assess the Brookhill Ferry Shipwreck on the Mississippi River in Baton Rouge, Louisiana. Photo courtesy of Washington State Division of Archaeology
Editor’s Note: This is the second part of a two-part series examining the impacts of climate change on archaeology. See part one about sea-level rise and its threats to coastal sites in the Spring 2025 issue of American Archaeology.
Along the shores and side canyons of the Colorado River, the past stands starkly exposed on land once covered by the largest man-made reservoir in the country. Upstream from the Hoover Dam, where a 24-year drought has left Lake Mead 160 feet below full pool, the ruins of the “lost city” of Pueblo Grande de Nevada are high and dry for the first time since the lake began filling 80 years ago.
Drought, flood, erosion, and fire have been fixtures of the human experience throughout time. But scientists say there is something different—and more ominous—in the recent intensity of climatic extremes. Droughts, by their nature, are transitory, but the U.S. Geological Survey has warned that climate change is making them “more frequent, longer, and more severe.” Droughts are deeper. Fires are burning more intensely. Glaciers are melting. Sea level is rising faster.
The world, in a word, is getting warmer. According to the World Meteorological Organization, the year 2024 was the warmest in recorded history. The second warmest was 2023. In fact, the ten warmest years on record are the last ten years. While many see the trend as a threat to the future, archaeologists also see it as a growing threat to the record of the past.
For archaeologists, the reemergence of Lake Mead’s “lost city” provides a new opportunity to study the ancestral Puebloans who inhabited the Nevada’s Moapa Valley more than a thousand years ago. But that opportunity comes at a price. The sprawling site, as well as a frontier ghost town abandoned in the 1930s when the reservoir began to fill, stands exposed to the elements—and worse. Unauthorized roads and trails now snake their way across the newly emergent land where Ancestral Puebloans lived a thousand years ago.
Scientists identify the fuels (combustible vegetation, live or dead) and fire behavior (movement of fire and its release of energy) that lead to adverse impacts to archaeological resources and sites in the Jemez Mountains in 2014. Treatments can then be designed to reduce risks. Photo by Rachel Loehman, U.S. Geological Survey
“There are no fences out there and there’s not much control over what happens,” said Desert Research Institute archaeologist Greg Haynes. “One person bulldozed a road through an archaeological site. We don’t know if people are taking things or not, but they are recreating anywhere they want.” He said cattle are often present, and they are “terribly destructive to archaeological sites, too.”
Further up the Colorado, behind the Glen Canyon Dam, water levels in Lake Powell hit a record low in 2023 and have yet to fully recover. With the “bathtub rings” that mark high water on the canyon walls 100 feet above current levels, many of its 2,000 archaeological sites—ancient rock art panels, dwellings, and burials stand newly exposed and largely unprotected.
“There’s a lot of looting and vandalism in exposed areas,” said Navajo Nation Tribal Culture Program archaeologist Erik Stanfield, who recently helped survey Glen Canyon for the National Park Service. “In some areas, we are seeing burials eroding out as the water level falls,” he said. “Large pictograph panels that were protected by the water are exposed again. There are structures covered with quagga mussels from their time underwater.”
Drought has gripped the American Southwest for 25 consecutive years. Tree ring data shows it to be the driest multi-decade period in the region since A.D. 800. Droughts, of course, are not new events in human experience.
This is an excerpt of ‘Drought, Flood, Fire, & Ice,’ in American Archaeology, Summer 2025, Vol. 29, and No. 2. Subscribe to read the full text.
FURTHER READING
- Climate Change and Your National Parks
- An Assessment of the Impacts of Climate Change on Cultural Heritage in Illinois
- Wildland Fire in Ecosystems Effects of Fire on Cultural Resources and Archaeology
- Extreme Precipitation in a Warming Climate
- Proceedings of the National Academy of Sciences: Archaeology, climate, and global change in the Age of Humans
