Appendix C

Glossary

Age–depth models: A quantitative relationship that establishes a chronology for sequential layers in a proxy archive, so that a given sample at a given depth in the archive can be related to a specific time (e.g., calendar date, or numbers of years before present). Age–depth models use a variety of different statistical techniques to establish likely age ranges for a given depth in an archive.

Analytical pipeline: A series of data-processing steps to prepare data for visualization, analysis, and modeling. Open-source and reproducible pipelines are important for ensuring transparency and reproducibility in scientific analysis.

Dendrochronology: The science of using the environmental information recorded by or in the exactly dated annual rings of trees to identify, understand, and quantify past changes or events in the Earth system.

Discoverability: The ease with which unknown information can be discovered by searching databases, the internet, and other sources. It differs from the term findability in that the search is for new information or data that the user does not yet know exists.

Ecosystem services: These are the direct and indirect benefits that ecosystems provide humans. Agroecosystems, rangelands, forests, and wetlands “provide provisioning services, regulating services, supporting services, and

cultural services” (de Groot et al., 2002; MEA, 2005) that support and sustain human livelihoods.

Extreme event: Any event that is sufficiently consequential, high-magnitude, rare, or rapid that it falls significantly outside the typical distribution of similar events can be considered within this category (e.g., Stewart et al., 2022). A broad set of criteria is adopted that allows an event to be defined by either its impact or its physical properties, such as absolute magnitude or recurrence rate.

Findability: The ease with which known information can be found by searching databases, the internet, and other sources. It differs from the term discoverability in that the search is for known information. The user knows the data or information exists and needs to locate it.

Information ecosystem: All structures, entities, and agents related to the flow of information relevant to a research domain, as well as the information itself.

Instrumental: Describes evidence that is sourced from engineered instruments that monitor the current state of the Earth system (e.g., weather stations, satellites, buoys, streamflow gauges, seismic monitoring stations). The temporal extent of instrumental records varies by measurement system and quickly fades back in time. For example, satellite-based observations of the Earth’s land surface extend back to the Landsat program in the early 1970s, while global networks of weather station records of temperature extend back to the late nineteenth century and a few individual records in Europe to the eighteenth century. For geographic locations, or intervals of Earth history, where or when instrumental evidence is lacking, paleoenvironmental data are necessary to reconstruct the past state of the Earth system.

Lacustrine deposits: The accumulations of sediments in a lake or wetland environment, composed of a combination of clastic material (sand, silt, and clay), organic matter, and chemical precipitates. Sedimentation is influenced by runoff, stream transport, aerial deposition, lake chemistry, nutrient availability, and basin shape. The physical and geochemical attributes of these sediments are excellent archives of past environmental conditions including extreme events such as major floods, earthquakes, volcanic eruptions, wildfires, and extreme temperature fluctuations.

Microfossil: The remains of organisms preserved in rock and sediment that are small enough to require a microscope to see them clearly (generally

1 mm or less but some fossils are as large as 2 mm in size). Scientists use these minute fossils to study past environmental conditions and evolution. Examples include pollen, bacteria, algae, foraminifera, ostracods, and many kinds of plankton.

Natural archive: Features of the Earth (e.g., tree rings, speleothems, corals, lake and ocean sediments, and other geological deposits, such as river terraces and alluvial fans) that preserve clues about past climate and environmental change. Because these materials build up in layers over time, they follow the principle of superposition; younger material is generally deposited on top of older material, which enables environmental history to be deciphered in chronological order.

Nonstationarity: Refers to the property of a set of data in the time domain where the statistical properties (for instance, the mean and the variance) change over time.

Observation: Any measurement or recording of some aspect of the Earth system. Observations may be visual, written, or measured, and can be from paleoenvironmental or instrumental methods. Observations are elements of empirical evidence, which, when assembled into large spatiotemporal datasets, are used to test and refine quantitative and conceptual models of the Earth system.

Paleocene–Eocene thermal maximum (PETM): A rapid and brief interval of extreme global warming (referred to as a hyperthermal event) that occurred approximately 56 million years ago near the transition between the Paleocene and Eocene epochs. The PETM is a prominent example in Earth history of how the global climate system responds to rapid introduction of greenhouse gases sourced from carbon stored in geological reservoirs, making it a target of intensive study in climate science.

Paleoecology: The ecology of the past. It is mainly concerned with reconstructing past relationships among biota, populations, communities, landscapes, environments, and ecosystems.

Paleoenvironmental: Defined here as referring to the processes, conditions, and living communities of past environments as preserved in natural archives, written records, oral traditions, or archaeological remains. Paleoenvironmental conditions are reconstructed by analyzing data from these archives of information to understand how climate and ecosystems have changed through time.

Paleoenvironmental data: Any data that can be used to infer past conditions of the Earth that include natural archives, written records, oral traditions, and archaeological information.

Paleohydrology: The study of the evidence of moving water and sediment in stream channels before the time of continuous (systematic) hydrologic records or direct measurements (Costa, 1987).

Paleoseismology: The study of ancient earthquakes, using a variety of paleoenvironmental evidence and proxies to reconstruct earthquake histories. Paleoseismology can provide recurrence estimates for seismic hazard risk assessment.

Paleotempestology: The study of past storm activity, most often focused on tropical cyclones (Minamidate and Goto, 2024).

Proxy: A measurable feature of the natural world formed in the past and preserved to the present that contains physical, biological, or chemical information about the environment in which it was formed. While sometimes used interchangeably with archive, proxies are more specifically the measurement(s) of physical, biological, or chemical properties of an archive that are used to reconstruct past environmental conditions.

Return period (recurrence interval): A statistical measurement or estimate of the average time between events; it is commonly used for climate, earthquake, and hydrologic hazards. For solid earth hazards such as earthquakes, scientists may use the equivalent term recurrence interval.

Seismite: A sedimentary layer or soft-sediment deformation feature formed by earthquake shaking of unconsolidated sediments, causing dewatering or liquefaction.

Speleothem: A calcium carbonate deposit that forms in caves through the evaporation and carbon dioxide degassing of waters that enter the cave from the overlying karst rock and soil. Speleothems are important natural archives of past environments and extreme events because they can be precisely dated and record the surface air temperatures and rainfall patterns of the past as well as extreme events such as floods, wildfires, earthquakes, and volcanic eruptions.

Stationarity: Refers to the property of a set of data in the time domain where the statistical properties (for instance, the mean and the variance) do not change over time.

Synthesis and translation center: Synthesis centers primarily focus on gathering and reanalyzing existing datasets, rather than collecting new measurements. Translation centers focus on building project-oriented teams and relationships between scientists and other stakeholders so scientific research can directly inform stakeholder priorities.

Tephra: The volcanic material ejected during an eruption, including ash and rock fragments. Tephra layers can be used to provide age estimates within an archive.

Translation: In the context of this report, the term translation represents the exchange of knowledge about the occurrence, impacts, and importance of extreme events between the scientists who generated this information and the local communities, actuaries, engineers, state and federal agencies, tribal communities, and other stakeholders who can take action to improve societal resilience to future extreme events, if given more precise knowledge about the probability and effect of past extreme events. This term is adopted from the fields of translational ecology and translational medicine (Enquist et al., 2017; Wall et al., 2017).