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1. Common Era sea-level budgets along the U.S. Atlantic coast

   https://doi.org/10.1038/s41467-021-22079-2  

   Walker, Jennifer S.; Kopp, Robert E.; Shaw, Timothy A.; Cahill, Niamh; Khan, Nicole S.; Barber, Donald C.; Ashe, Erica L.; Brain, Matthew J.; Clear, Jennifer L.; Corbett, D. Reide; et al (December 2021, Nature Communications)

   null (Ed.)

   Abstract Sea-level budgets account for the contributions of processes driving sea-level change, but are predominantly focused on global-mean sea level and limited to the 20th and 21st centuries. Here we estimate site-specific sea-level budgets along the U.S. Atlantic coast during the Common Era (0–2000 CE) by separating relative sea-level (RSL) records into process-related signals on different spatial scales. Regional-scale, temporally linear processes driven by glacial isostatic adjustment dominate RSL change and exhibit a spatial gradient, with fastest rates of rise in southern New Jersey (1.6 ± 0.02 mm yr −1 ). Regional and local, temporally non-linear processes, such as ocean/atmosphere dynamics and groundwater withdrawal, contributed between −0.3 and 0.4 mm yr −1 over centennial timescales. The most significant change in the budgets is the increasing influence of the common global signal due to ice melt and thermal expansion since 1800 CE, which became a dominant contributor to RSL with a 20th century rate of 1.3 ± 0.1 mm yr −1 . 

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2. Climate pacing of millennial sea-level change variability in the central and western Mediterranean

   https://doi.org/10.1038/s41467-021-24250-1  

   Vacchi, Matteo; Joyse, Kristen M.; Kopp, Robert E.; Marriner, Nick; Kaniewski, David; Rovere, Alessio (December 2021, Nature Communications)

   Abstract Future warming in the Mediterranean is expected to significantly exceed global values with unpredictable implications on the sea-level rise rates in the coming decades. Here, we apply an empirical-Bayesian spatio-temporal statistical model to a dataset of 401 sea-level index points from the central and western Mediterranean and reconstruct rates of sea-level change for the past 10,000 years. We demonstrate that the mean rates of Mediterranean industrial-era sea-level rise have been significantly faster than any other period since ~4000 years ago. We further highlight a previously unrecognized variability in Mediterranean sea-level change rates. In the Common Era, this variability correlates with the occurrence of major regional-scale cooling/warming episodes. Our data show a sea-level stabilization during the Late Antique Little Ice Age cold event, which interrupted a general rising trend of ~0.45 mm a −1 that characterized the warming episodes of the Common Era. By contrast, the Little Ice Age cold event had only minor regional effects on Mediterranean sea-level change rates. 

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3. A noisy-input generalized additive model for relative sea-level change along the Atlantic coast of North America

   https://doi.org/10.1093/jrsssc/qlae044  

   Upton, Maeve; Parnell, Andrew; Kemp, Andrew; Ashe, Erica; McCarthy, Gerard; Cahill, Niamh (September 2024, Journal of the Royal Statistical Society Series C: Applied Statistics)

   Abstract We propose a Bayesian, noisy-input, spatial–temporal generalized additive model to examine regional relative sea-level (RSL) changes over time. The model provides probabilistic estimates of component drivers of regional RSL change via the combination of a univariate spline capturing a common regional signal over time, random slopes and intercepts capturing site-specific (local), long-term linear trends and a spatial–temporal spline capturing residual, non-linear, local variations. Proxy and instrumental records of RSL and corresponding measurement errors inform the model and a noisy-input method accounts for proxy temporal uncertainties. Results highlight the decomposition of regional RSL changes over 3,000 years along North America’s Atlantic coast. The physical process glacial isostatic adjustment prevailed before 1800 CE, with anthropogenic forcing dominating after 1900 CE. 

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4. The Influence of Future Changes in Tidal Range, Storm Surge, and Mean Sea Level on the Emergence of Chronic Flooding

   https://doi.org/10.1029/2023EF003993  

   Hague, Ben S; Talke, Stefan A (February 2024, Earth's Future)

   Abstract Sea‐level rise is leading to increasingly frequent coastal floods globally. Recent research shows that changes in tidal properties and storm surge magnitudes can further exacerbate sea‐level rise‐related increases in flood frequencies. However, such non‐stationarity in tide and storm surge statistics are largely neglected in existing coastal flood projection methodologies. Here we develop a framework to explore the effect that different realizations of various sources of uncertainty have on projections of coastal flood frequencies, including changes in tidal range and storminess. Our projection methodology captures how observed flood rates depend on how storm surges coincide with tidal extremes. We show that higher flood rates and earlier emergence of chronic flooding are associated with larger sea‐level rise rates, lower flood thresholds, and increases in tidal range and skew surge magnitudes. Smaller sea‐level rise rates, higher flood thresholds and decreases in sea level variability lead to commensurately lower flood rates. Percentagewise, changes in tidal amplitudes generally have a much larger impact on flood frequencies than equivalent percentagewise changes in storm surge magnitudes. We explore several implications of these findings. Firstly, understanding future local changes in storm surges and tides is required to fully quantify future flood hazards. Secondly, existing hazard assessments may underestimate future flood rates as changes in tides are not considered. Finally, identifying the flood frequencies and severities relevant to local coastal managers is imperative to develop useable and policy‐relevant projections for decisionmakers. 

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5. Climate did not drive Common Era Maldivian sea-level lowstands

   https://doi.org/doi:10.1038/s41561-021-00731-2  

   Piecuch, Christopher G.; Kemp, A. C.; Gebbie, G.; Meltzner, A. (April 2021, Nature geoscience)

   Super, J. (Ed.)

   Reconstructions of Common Era sea level are informative of relationships between sea level and natural climate variability, and the uniqueness of modern sea-level rise1. Kench et al.2 recently reconstructed Common Era sea level in the Maldives, Indian Ocean, using corals, and reported periods of 150–500 years when sea level fell and rose at average rates of 2.7–4.3 mm yr−1, which they attributed to ocean cooling and warming inferred from reconstructions of sea-surface temperature (SST) and radiative forcing (Fig. 2 of ref. 2). We challenge their interpretation, using principles of sea-level physics to argue that pre-industrial radiative forcing and SST changes were insufficient to cause thermosteric sea-level (TSL) trends as large as reported for the Maldives2. Our results support the paradigm that modern rates and magnitudes of sea-level rise due to climate change are unprecedented during the Common Era3,4. 

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