In recent years, concerns about the damaging effects of anthropogenic global climate change have been amplified by the increasing frequency of destructive weather events, large-scale wildfires and droughts, and a growing body of evidence indicating sea levels will rise appreciably over the next several centuries, from 1 m in the next century to 5 m or more in the centuries thereafter ([1–4]). The effects of such increases in sea level will be severe and long-lasting. At present, over 40% of all people worldwide live within a 100 km distance from the nearest coastline, many in low lying areas vulnerable to sea level rise [5–11]. Should projected rises occur, the effect on humans living on and near the coast, including the loss of infrastructure is nearly incalculable, and will require population movement and resettlement on scales unprecedented in human history. Here we demonstrate, using examples from the southeastern United States, that not only modern populations and properties, but also irreplaceable heritage in the form of the physical record of past human settlements, are currently vulnerable to projected sea level rise as a destructive agent. We argue that archaeologists and society at large should direct increased attention to planning for and mitigating these losses to heritage resources.
The worldwide historic preservation community has begun to express serious concerns over the threat of global climate change to the archaeological and historic record, especially with respect to the potential loss of data that will occur as coastal zones are subjected to increased erosional forces and inundation from rising sea levels [12–35]). Analyses have been directed to determining how rising or fluctuating sea levels damage archaeological and historical resources, sacred and traditional sites, as well as submerged resources like former terrestrial archaeological sites, buildings, and shipwrecks [36–45]. Threats to coastal and near-coastal cultural resources will also come from activities undertaken to resist rising waters. Sea walls and other barriers may provide protection to critical coastlines at favorable cost benefit tradeoffs , but their construction will potentially impact large numbers of existing and undocumented cultural resources, far exceeding work conducted as a result of recent oil spills like the Exxon Valdez in Alaska and Deepwater Horizon along the southeastern Gulf coast [47–50]. Far less consideration has been given to the damage or loss of cultural resources that will occur as populations residing in coastal areas are displaced inland, building new communities or expanding existing ones. In previously less-developed regions, where little prior archaeological work has occurred, innumerable unrecorded archaeological and historical sites will also be threatened. The salvaging of valuable materials from threatened infrastructure itself will likely take a toll on historic properties, although some of the more iconic buildings may themselves be relocated to higher ground. For example, the White House or the Lincoln Memorial may be moved from Washington, D.C., much like the Egyptian New Kingdom era temple of Abu Simbel was moved before the rising waters of the Aswan High Dam submerged the area in the 1960s, and the Cape Hatteras lighthouse was relocated 2,900 feet to protect it from encroaching seas in 1999 [32, 51, 52].
Damage from shoreline erosion represents a significant concern to preservationists, with appreciable research globally now being directed to well-known archaeological and historical resources threatened by such processes [19, 24, 25, 27–45]. Important research is addressing the threat of global climate change, particularly sea level rise, to national landmarks or national parks in the United States [19, 21, 28, 29, 32, 53, 54]. However, more inclusive and geographically broad-based analyses are rare, because comprehensive data sets encompassing all known archaeological and historical resources at regional or continental scales have not previously been available. In the United States, cultural resource data are managed at the state rather than the national level, or within specific federal agencies, making such database development and large-scale analyses challenging. Integrating these data together is crucial to determining how climate change, including fluctuations in sea-level, will impact heritage resources at regional and continental scales. Calls for such syntheses have recently appeared [55, 56], and fostering research on this scale is widely heralded as a grand challenge facing the archaeological profession in the United States [57, 58], essential to exploring questions about changes over time in organizational complexity, human responses to climate change, and long-term settlement dynamics [31, 59–70].
Linked database development: The DINAA project
The Digital Index of North American Archaeology [71–73], or DINAA, permits the examination of relationships between environmental and cultural resources over large areas, by rendering diverse heritage data sets interoperable, and linking them with natural systems data sets encompassing physiography, biota, and climate in the past, present, and projected into the future. A multi-institutional collaboration, DINAA consists of an online, integrated open-source database of archaeological and other kinds of evidence for North America’s human settlement. Since 2012, DINAA has compiled and rendered interoperable archaeological site file data from 15 states in Eastern North America (N = 505,056 sites). This work has been done in consultation and cooperation with government, academic, and tribal stakeholders, and with funding from the National Science Foundation, the Institute of Museum and Library Services, and support from the leadership of archaeological professional organizations, including the Society for American Archaeology, the Society for Historical Archaeology, and the Archaeology Division of the American Anthropological Association  (Fig 1). As of October 2017, personnel from 21 states are actively participating in DINAA development, and the project has initiated discussions with site file managers and governing authorities in the remaining 28 states in continental North America, and in other countries, with the goal of developing a truly continental database. Information rendered accessible through DINAA is seeing increasing attention and use by researchers and resource managers, enhancing public awareness, education, and appreciation for scientific research in general and archaeology in particular [74–86].
Data: . Ohio and most Pennsylvania site data is at county-level resolution.
DINAA is a publicly accessible compilation of existing archaeological site file, collection, and report data from multiple regional, state, and local repositories, linked with other archaeological databases as well as modern and paleoenvironmental data sets, with site numbers serving as the basic identifier and standardized temporal metadata as a relational control between data sets, to permit analyses by selected time periods. Archaeological site files contain data and metadata about the chronology, location, and function of sites, in combination with other information that can include diagnostic artifact descriptions, radiocarbon and other absolute dating determinations, and bibliographic citations. While each state and agency uses somewhat different systems, they are rendered interoperable through DINAA.
Through deployment on Open Context , an open data publishing service for archaeology, DINAA embraces current best practices in scientific data-management including open standards and open licensing, transparent version control of both data and source code, Linked Data, and iterative development. Through aggregation and human editorial processes to align data set schemas and controlled vocabularies, DINAA provides some of the benefits of centralization without requiring different (and typically financially constrained) state agencies to change their own systems. Thus, DINAA fosters independent development and experimentation through integration of distributed systems managed by a host of institutions. This approach enables community-wide participation and investment in archaeological informatics, making the resulting cyberinfrastructure products shared and useful for all.
DINAA also strictly conforms to legal requirements regarding the maintenance and use of cultural resources data. While analyses like those reported herein can occur making use of records with specific geospatial data, the data itself and permission to use it must be obtained from the agencies maintaining the information. DINAA, accordingly, does not publish or store precise site coordinates online, and the project redacts other sensitive attributes, particularly property ownership, from state site file repositories, in consultation with agency and other interested parties, including tribal nations. Directions to offices to contact to obtain such information for each site are provided with analytical output, but DINAA itself does not maintain or release such data. For public display purposes DINAA site data is aggregated within a tiled web map in Open Context, where a map-tiling algorithm allocates each site record to a 0.176 degree grid cell in the WGS Web Mercator projection (roughly 20×20 km at the equator). The Open Context platform provides publicly accessible online map interfaces for visualization and queries at a low level of spatial resolution that still has great utility when examining distributions encompassing large areas or time periods. DINAA digital data are archived with the California Digital Library, and mirrored in repositories in other countries to ensure long term survival [71, 72].
Indexing, or linking to and rendering interoperable data from many sources and across disciplines is a major function of DINAA, increasing its utility for resource management, research, and public education (Fig 2). By cross-referencing distributed collections on the Web, DINAA enables users to find and access relevant content in archaeological systems like Archaeology Southwest , the Paleoindian Database of the Americas [88, 89], the Eastern Woodlands Household Archaeology Database Project , the Canadian Archaeological Radiocarbon Database , the Digital Archaeological Archive of Comparative Slavery , the Chaco Research Archive , PeriodO , and The Digital Archaeological Record . Aggregators such as Pelagios , a collaborator with DINAA, can then “harvest” cross-references between different systems to present users with services, maps, and visualization tools to discover related data and other media that relate to DINAA curated site files. DINAA can serve as a key node in connecting North American archaeological data, allowing, for the first time, its linkage across multiple time periods and geographic regions, and using an array of environmental data sets to explore fundamental issues such as changes in human land use over time; the nature of the archaeological record collected over the past century, including the identification of research strengths and gaps; and, as we show here, how future changes in climate will affect site preservation and heritage management.
DINAA directs users to these outlets, but access and content control remains on their systems (black arrows indicate existing linkages, white arrows indicate linkages under development).