In the far corner of northwestern Alaska, Cape Krusenstern National Monument stands testament to human adaptations to climate change for over 5,000 years.
Over 5,000 years ago, beach ridges began to form along the coast of Cape Krusenstern. Changing climatic conditions meant that the sea level and the energy and direction of waves shifted over time, affecting when and how the coastline formed. Beach ridges built up during warm periods at 2400–1600 B.P.* and 1650–1240 B.P., only to erode during stormy colder periods at 1600–1200 B.P., 1150–900 B.P., and 500–150 B.P. The beach ridges not only capture past fluctuations in sea level, wave energy and wave direction, but also the ways that people adapted over thousands of years to a changing climate. (*B.P. means "before present" and refers to time before 1950, which can be dated using carbon-14 dating.)
From the beach ridges, archeologists found evidence of every known cultural tradition in northwest Alaska from the past 5,500 years. Archeological sites on the bluff behind the beach ridges may date as early as 9000 B.P. Among the cultures represented were the American Paleo Arctic, Denbigh, Choris, Norton, Ipiutak, Birnirk, and Western Thule, as well as historic whaling and modern Iñupiat.
Archeological resources at Cape Krusenstern tell us about the earliest Americans and the ancestors of Eskimo societies still living in the region. Climate influenced where people settled, what they ate, how quickly their technology changed, and every other facet of life. For example, radiocarbon dating shows that people lived on the coast during warm periods, when the beach ridges built up. They settled inland during cooler, stormier periods.
People adapted to where the climate pushed food resources, especially meat. On a seasonal basis, the Lower Noatak and Kotzebue (who are traditionally associated with the ridges) hunted marine animals during spring thaw, fished in summer and fall, then moved inland toward caribou during their spring and fall migrations. During cooler climatic periods along the coast, resources became more scarce. For example, the Inuipiats responded to climate change by moving up the Kobuk River, adapting land uses and tools specializing in caribou.
Some artifacts recovered from the beach ridges, especially stone tools, share characteristics with finds from Russia, Siberia, and other places in Asia. They point to human migration at a time when the sea level was low and crossing the Bering Strait was possible by foot. Other sites point to more recent settlements by ancestors of the Iñupiat and other tribes.
Part of the American story—the migration of peoples, the lifeways of Native Alaskans—is threatened by climate change due to impacts on archeological sites. Scientists say that the rate of coastal change is unlike anything ever seen since humans came to the continent. Climate change is affecting Alaska dramatically—more than anywhere else in the United States. Scientists anticipate increasing annual and seasonal temperatures and melting glaciers and permafrost. As a result, they predict changes to regional hydrology, drainage, and landscape morphology.
The beach ridges are susceptible to coastal erosion, rising sea level, and slumping due to thawing permafrost. Such changes to the landscape have especially damaging impacts to archeological resources and the cultural history associated with them. In particular, sea level rise and a renewed period of coastal storminess associated with climate change threaten to erode or submerge many of the precious records and resources contained in the beach ridge complex. Slumping and landslides resulting from melting permafrost also threaten to compromise the integrity of archeological sites. Recent studies at Cape Krusenstern found seven fresh landslides that result from permafrost thaw.
Cape Krusenstern's beach ridges will record these changes—as well as any future changes—just as they have recorded the changes over the past 5,000 years.
Shelby Anderson, Cape Krusenstern Human-Environmental Dynamics Project- Two Hundred Years: on the beach of their time, Department of Anthropology, University of Washington/National Park Service: 2008.
J. L. Giddings and D.D Anderson, Beach Ridge Archaeology of Cape Krusenstern. National Park Service, Publications in Archaeology No. 20, U.S. Department of the Interior, Washington, D. C.: 1986 ed.
Caroline Jezierski, Rachel Loehman, and Amanda Schramm, Understanding the Science of Climate Change: Talking points - impacts to Alaska Boreal and Arctic. Natural Resource Report NPS/NRPC/NRR, National Park Service: 2010.
J. W. Jordan and O.K. Mason, "A 5000 Year Record of Intertidal Peat Stratigraphy and Sea Level Change from Northwest Alaska," Quaternary International 1999, 60:37-47.
Jim Lawler and Sara Wesser, Climate Change Resource Brief for the Arctic Network: Bering Land Bridge National Preserve, Cape Krusenstern National Monument, Noatak National Preserve, Kobuk Valley National Preserve, and Gates of the Arctic National Park and Preserve, National Park Service, Alaska Region Inventory and Monitoring Program, 2010: 1-2
Owen K. Mason and S. Craig Gerlach, “Chukchi Hotspots, Paleo-Polynas, and Caribou Crashes: Climatic and Ecological Dimensions of North Alaska Prehistory”, Arctic Anthropology vol. 32, no. 1, 1995: 101-130