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Vertical land motion is a key component of relative sea-level changes in coastal areas. Rates of vertical land motion can vary temporally owing to anthropogenic and natural processes. Yet, such nonlinear behaviour has not been fully accounted for in twentieth-century sea-level budgets or projections because long-term observations at relevant spatial scales are scarce. Here we infer vertical land motion at a global set of tide gauge stations by comparing their records with a probabilistic reconstruction of climate-related sea level (1900–2021) that integrates model-based estimates of sterodynamic, barystatic and inverse-barometer contributions. Differences between climate-related sea-level and tide gauge records primarily reflect vertical land motion and reveal previously unreported temporal variations linked to subsurface fluid withdrawal, as well as seismic and volcanic processes. We show that decadal fluctuations in regional relative sea-level trends can exceed those driven by climate-related processes by an order of magnitude. Consequently, vertical land motion projections based on linear extrapolations introduce systematic median sea-level projection errors of typically up to 7.6 mm yr−1 at sites influenced by seismic or volcanic activity and 5.6 mm yr−1 at the other sites. Our time-varying vertical land motion estimates constrain geophysical models of anthropogenic and volcano-tectonic crustal processes and pave the way for more robust sea-level projections at tide gauges. 

Abstract Compound floods are often thought of as large, infrequent floods during which extremes of coastal sea level and/or river flow combine with each other or additional factors (e.g., tides and rainfall) to induce major flooding. However, little is known about the potentially compound nature of more frequent, lower‐level floods. Here, we introduce the term “compound minor floods” to define minor floods composed of two or more water‐level sources. We use the Delaware River Estuary as a case study to investigate the prevalence and composition of these minor compound floods along the extent of a tidal river. We apply multiple linear regression to a 22‐year time series of coastal water levels and river discharge to establish the contributions of tides, nontidal open‐ocean effects, and river discharge to minor flood events at eight locations along the tidal Delaware River. We find that most minor flood events are compound in nature, requiring at least two components (e.g., tides and river discharge) to initiate flooding. We identify spatial structure in the relative importance of oceanographic and riverine contributions to minor flooding along the tidal reach of the estuary. These results suggest that incorporating fluvial components into minor flooding assessments is important to fully characterize flood risk along tidal rivers and estuaries. 

Abstract High‐tide flooding—minor, disruptive coastal inundation—is expected to become more frequent as sea levels rise. However, quantifying just how quickly high‐tide flooding rates are changing, and whether some places experience more high‐tide flooding than others, is challenging. To quantify trends in high‐tide flooding from tide‐gauge observations, flood thresholds—elevations above which flooding begins—must be specified. Past studies of high‐tide flooding in the United States have used different data sets and approaches for specifying flood thresholds, only some of which directly relate to coastal impacts, which has lead to sometimes conflicting and ambiguous results. Here we present a novel method for quantifying, with uncertainty, high‐tide flooding thresholds along the United States coast based on sparsely available impact‐based flood thresholds. We use those newly modeled thresholds to make an updated assessment of changes in high‐tide flooding across the United States over the past few decades. From 1990–2000 to 2010–2020, high‐tide flooding rates almost certainly (probability ) increased along the United States East Coast, Gulf Coast, California, and Pacific Islands, while they very likely decreased along Alaska during that time; significant changes in high‐tide flooding rates between the two decades were not detected in Oregon, Washington, and the Caribbean. Averaging spatially, we find that high‐tide flooding rates probably more than doubled nationally between 1990–2000 and 2010–2020. Our approach lays a foundation for future studies to more accurately model high‐tide flood thresholds and trends along the global coastline. 

This repository contains hourly Shelfbreak jet transport (Sv) derived from the three central moorings of the OOI Coastal Pioneer Array (https://ooinet.oceanobservatories.org/).  Transport is computed from east velocity component (u, in m/s), which is then depth integrated from 15 until 115m. The depth integrated velocity (m2/s) is transformed in transport considering a jet width of 40 km, and then converted into Sv (by dividing by 10^6 factor). Thus, to convert the transport time series back to m2/s, the time series must be divided by 4.10^10. Tides were removed from the velocity component, with Utide harmonic estimation, using the 68 standard tidal coefficients, except for the Semi-annual and Annual components (Sa and SSa). First column: date (datetime format, year-month-day hour:min:second)Second column: Qy (jet transport, in Sv)   accompanying paper: Camargo, C. M. L., Piecuch, C. G., & Raubenheimer, B. (2024). From Shelfbreak to Shoreline: Coastal sea level and local ocean dynamics in the northwest Atlantic. Geophysical Research Letters, 51, e2024GL109583. https://doi.org/10.1029/2024GL109583 

Abstract The Gulf Stream is a vital limb of the North Atlantic circulation that influences regional climate, sea level, and hurricane activity. Given the Gulf Stream's relevance to weather and climate, many studies have attempted to estimate trends in its volumetric transport from various data sets, but results have been inconclusive, and no consensus has emerged whether it is weakening with climate change. Here we use Bayesian analysis to jointly assimilate multiple observational data sets from the Florida Straits to quantify uncertainty and change in Gulf Stream volume transport since 1982. We find with virtual certainty (probabilityP > 99%) that Gulf Stream volume transport through the Florida Straits declined by 1.2 ± 1.0 Sv in the past 40 years (95% credible interval). This significant trend has emerged from the data set only over the past ten years, the first unequivocal evidence for a recent multidecadal decline in this climate‐relevant component of ocean circulation. 

Abstract. Identifying the causes for historical sea-level changes in coastal tide-gauge records is important for constraining oceanographic, geologic, and climatic processes. The Río de la Plata estuary in South America features the longest tide-gauge records in the South Atlantic. Despite the relevance of these data for large-scale circulation and climate studies, the mechanisms underlying relative sea-level changes in this region during the past century have not been firmly established. I study annual data from tide gauges in the Río de la Plata and stream gauges along the Río Paraná and Río Uruguay to establish relationships between river streamflow and sea level over 1931–2014. Regression analysis suggests that streamflow explains 59 %±17 % of the total sea-level variance at Buenos Aires, Argentina, and 28 %±21 % at Montevideo, Uruguay (95 % confidence intervals). A long-term streamflow increase effected sea-level trends of 0.71±0.35 mm yr−1 at Buenos Aires and 0.48±0.38 mm yr−1 at Montevideo. More generally, sea level at Buenos Aires and Montevideo respectively rises by (7.3±1.8)×10-6 m and (4.7±2.6)×10-6 m per 1 m3 s−1 streamflow increase. These observational results are consistent with simple theories for the coastal sea-level response to streamflow forcing, suggesting a causal relationship between streamflow and sea level mediated by ocean dynamics. Findings advance understanding of local, regional, and global sea-level changes; clarify sea-level physics; inform future projections of coastal sea level and the interpretation of satellite data and proxy reconstructions; and highlight future research directions. Specifically, local and regional river effects should be accounted for in basin-scale and global mean sea-level budgets as well as reconstructions based on sparse tide-gauge records.