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We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on various time scales and present a new sea-level record for the past 100 million years (My). Long-term sea level peaked at 100 ± 50 meters during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. Sea level mirrors oxygen isotope variations, reflecting ice-volume change on the 10⁴- to 10⁶-year scale, but a link between oxygen isotope and sea level on the 10⁷-year scale must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past 100 My, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5 Ma to the present).

In the largest global cooling event of the Cenozoic Era, between 33.8 and 33.5 Myr ago, warm, high-CO 2 conditions gave way to the variable ‘icehouse’ climates that prevail today. Despite intense study, the history of cooling versus ice-sheet growth and sea-level fall reconstructed from oxygen isotope values in marine sediments at the transition has not been resolved. Here, we analyse oxygen isotopes and Mg/Ca ratios of benthic foraminifera, and integrate the results with the stratigraphic record of sea-level change across the Eocene–Oligocene transition from a continental-shelf site at Saint Stephens Quarry, Alabama. Comparisons with deep-sea (Sites 522 (South Atlantic) and 1218 (Pacific)) δ 18 O and Mg/Ca records enable us to reconstruct temperature, ice-volume and sea-level changes across the climate transition. Our records show that the transition occurred in at least three distinct steps, with an increasing influence of ice volume on the oxygen isotope record as the transition progressed. By the early Oligocene, ice sheets were ∼25% larger than present. This growth was associated with a relative sea-level decrease of approximately 105 m, which equates to a 67 m eustatic fall. The Eocene–Oligocene transition is the largest global cooling in the Cenozoic period. A comparison of three independent proxies from the continental shelf and deep ocean reveals a three-step transition to cold glacial conditions, with ice sheets 25% larger than their present size.

The geologic record provides constraints on the rates, amplitudes, and mechanisms controlling globally averaged (eustatic) and relative (eustatic plus subsidence/uplift) changes of sea level on various time scales. On geological time scales, global sea level changes are tied primarily to long-term (10⁷–10⁸-year scale) tectonism and short-term (10³–10⁶-year scale) changes in continental ice volume, though recent studies also illustrate the importance of tectonism on 10⁶-year time scales. The history of 10⁶-year scale eustatic changes has been controversial; the most widely used sea level curves agree with independently derived estimates with regard to the ages of sea level falls, but depart significantly from more recent studies with regard to amplitudes. We present a 180-million-year history of sea level changes. A global sea level rise of 120 m followed the Last Glacial Maximum, with rates that exceeded 10 times the modern rate of rise (> 40 mm yr⁻¹ versus ~ 3 mm yr⁻¹). The \"ice ages\" of the past 2.6 million years were due to growth/decay of large Northern Hemisphere ice sheets. Those of the past 780,000 years caused sea level changes that were large (> 100 m) and paced primarily by the ~100,000 year eccentricity cycle; smaller changes (typically < 60 m) prior to this time were paced primarily by the 41,000-year tilt cycle. The growth and decay of a continental-scale ice sheet in Antarctica caused 50–60-m variations on the 10⁶-year scale beginning ~ 33.5 million years ago. Prior to this time, Earth had been a warm, high-CO₂ \"greenhouse\" world that was largely ice-free back to 260 million years ago, though recent evidence suggests that 15–25-m sea level changes may have been caused by the growth and decay of small, ephemeral continental ice sheets.

We evaluate paleo‐, historical, and future sea‐level rise along the U.S. mid‐Atlantic coast. The rate of relative sea‐level rise in New Jersey decreased from 3.5 ± 1.0 mm/yr at 7.5–6.5 ka, to 2.2 ± 0.8 mm/yr at 5.5–4.5 ka to a minimum of 0.9 ± 0.4 mm/yr at 3.3–2.3 ka. Relative sea level rose at a rate of 1.6 ± 0.1 mm/yr from 2.2 to 1.2 ka (750 Common Era [CE]) and 1.4 ± 0.1 mm/yr from 800 to 1800 CE. Geological and tide‐gauge data show that sea‐level rise was more rapid throughout the region since the Industrial Revolution (19th century = 2.7 ± 0.4 mm/yr; 20th century = 3.8 ± 0.2 mm/yr). There is a 95% probability that the 20th century rate of sea‐level rise was faster than it was in any century in the last 4.3 kyr. These records reflect global rise (∼1.7 ± 0.2 mm/yr since 1880 CE) and subsidence from glacio‐isostatic adjustment (∼1.3 ± 0.4 mm/yr) at bedrock locations (e.g., New York City). At coastal plain locations, the rate of rise is 0.3–1.3 mm/yr higher due to groundwater withdrawal and compaction. We construct 21st century relative sea‐level rise scenarios including global, regional, and local processes. We project a 22 cm rise at bedrock locations by 2030 (central scenario; low‐ and high‐end scenarios range of 16–38 cm), 40 cm by 2050 (range 28–65 cm), and 96 cm by 2100 (range 66–168 cm), with coastal plain locations having higher rises (3, 5–6, and 10–12 cm higher, respectively). By 2050 CE in the central scenario, a storm with a 10 year recurrence interval will exceed all historic storms at Atlantic City. Summary An analysis of geological and historical sea‐level records shows a significant rate of increase in sea‐level rise since the nineteenth century. In New Jersey, it is extremely likely that sea‐level rise in the twentieth century was faster than during any other century in the last 4.3 thousand years. Accounting for regional and local factors, the authors project sea‐level rise in the mid‐Atlantic U.S. most likely about 38–42′′ (96–106 cm) over the twentieth century, but possibly as high as 66–71′′ (168–180 cm). Key Points Controls on relative sea‐level rise in the U.S. mid‐Atlantic region Current relative sea‐level rise is unprecedented over past 4.3 kyr Regional sea‐level projections for bedrock and coastal plain sites

Studies of ancient sea levels provide insights into the mechanisms and rates of sea level changes due to tectonic processes (e.g., ocean crust production) and climatic variations (e.g., insolation due to Earth’s orbital changes and atmospheric CO₂). Global mean sea level (GMSL) changes since the Middle Eocene (ca. 48 million years ago [Ma]) have been primarily driven by ice volume changes paced on astronomical timescales (2400, 1200, 95/125, 41, and 19/23 thousand years [kyr]), modulated by changes in atmospheric CO₂. During peak warm intervals (e.g., Early Eocene Climatic Optimum 56–48 Ma and the early Late Cretaceous ca. 100–80 Ma), atmospheric CO₂ was high and Earth was more than 5°C warmer and mostly ice-free, contributing ~66 m of GMSL rise from ice alone. However, even in the warmest times (e.g., Early Eocene, ca 50 Ma), growth and decay of small ice sheets (25 m sea level equivalent) likely drove sea level changes that inundated continents and controlled the record of shallow-water deposits. Ice sheets were confined to the interior of Antarctica prior to the Oligocene and first reached the Antarctic coast at 34 Ma, with the lowest sea levels –20±10 m relative to modern GMSL. Following a near ice-free Miocene Climatic Optimum (17–13.8 Ma), a permanent East Antarctic Ice Sheet (EAIS) developed in the Middle Miocene (ca. 13.8 Ma). During the Pliocene (4–3 Ma), CO₂ was similar to 2020 CE (Common Era) and sea levels stood ~22±10 m above present, requiring significant loss of the Greenland Ice Sheet (~7 m of sea level), West Antarctic Ice Sheet (~5 m after isostatic compensation), and vulnerable portions of the EAIS. The small Northern Hemisphere ice sheets of the Eocene to Pliocene expanded into continental scale in the Quaternary (past 2.55 million years). Sea level reached its lowest point (~130 m below present) during the Last Glacial Maximum (ca. 27–20 thousand years before 1950 [ka]), episodically rose during the deglaciation (ca. 20–11 ka) at rates that at times were in excess of 47 mm yr–1 (vs. modern rates of 3.2 mm yr–1), and progressively slowed during the Early to Middle Holocene from ca. 11 ka until ~4 ka. During the Late Holocene (last 4.2 kyr, including the CE), GMSL only exhibited multi-centennial variability of ±0.1 m. The modern episode of GMSL rise began in the late nineteenth century, with most of the twentieth century rise attributable to global warming and ice melt. Under moderate emissions scenarios, GMSL is likely to rise 0.4–1.0 m in this century, with ancient analogs suggesting a longer term (centennial to millennial scale) equilibrium rise of ~10 m. Under higher emissions scenarios, twenty-first century GMSL will rise greater than 2 m, and in the long term, tens of meters cannot be excluded.

The release of over 4500 Gt (gigatonnes) of carbon at the Paleocene–Eocene boundary provides the closest geological analog to modern anthropogenic CO2 emissions. The cause(s) of and responses to the resulting Paleocene–Eocene Thermal Maximum (PETM) and attendant carbon isotopic excursion (CIE) remain enigmatic and intriguing despite over 30 years of intense study. CIE records from the deep sea are generally thin due to its short duration and slow sedimentation rates, and they are truncated due to corrosive bottom waters dissolving carbonate sediments. In contrast, PETM coastal plain sections along the US mid-Atlantic margin are thick, generally having an expanded record of the CIE. Drilling here presents an opportunity to study the PETM onset to a level of detail that could transform our understanding of this important event. Previous drilling in this region provided important insights, but existing cores are either depleted or contain stratigraphic gaps. New core material is needed for well-resolved marine climate records. To plan new drilling, members of the international scientific community attended a multi-staged, hybrid scientific drilling workshop in 2022 designed to maximize not only scientifically and demographically diverse participation but also to protect participants' health and safety during the global pandemic and to reduce our carbon footprint. The resulting plan identified 10 sites for drill holes that would penetrate the Cretaceous–Paleogene (K–Pg) boundary, targeting the pre-onset excursion (POE), the CIE onset, the rapidly deposited Marlboro Clay that records a very thick CIE body, and other Eocene hyperthermals. The workshop participants developed several primary scientific objectives related to investigating the nature and the cause(s) of the CIE onset as well as the biotic effects of the PETM on the paleoshelf. Additional objectives focus on the evidence for widespread wildfires and changes in the hydrological cycle, shelf morphology, and sea level during the PETM as well as the desire to study both underlying K–Pg sediments and overlying post-Eocene records of extreme hyperthermal climate events. All objectives address our overarching research question: what was the Earth system response to a rapid carbon cycle perturbation?

We describe seven Paleocene to lowermost Eocene sequences in core holes at Island Beach, Bass River, Ancora, Millville, and Sea Girt, NJ (Ocean Drilling Program Leg 150X, 174AX) and analyze benthic foraminiferal assemblages to assess paleodepth changes within sequences. These sequences are referred to as Pa0, Pa1a, Pa1b, Pa2a, Pa2b, Pa3a, and Pa3b. Paleocene sequence boundaries are identified by unconformities and variations in benthic foraminiferal biofacies. We used Q-mode factor analysis and paleoslope modeling to identify three distinct middle-outer neritic benthic foraminiferal assemblages and their associated water depths. Paleodepths during the early Paleocene and deposition of Pa0, Pa1a, and Pa2b were ~80 m with ~20 m changes across sequence boundaries. A long-term shallowing occurred through the late Paleocene where paleodepths were ~5070 m in Pa3a. This trend drastically changes in the earliest Eocene where the paleodepths of sequence Pa3b were ~120150 m. New Jersey Paleocene sequence boundaries correlate with those in other regions and with 18O increases in the deep sea, suggesting Paleocene eustatic lowerings were associated with ice-growth events.

We present measurements of the in situ, microscopic architecture of a self- assembled bilayer at the interface between a regularly nanopatterned surface and an aqueous sub-phase using neutron reflectometry. The substrate is patterned with a rectangular array of nanoscale holes. Because of the high quality of the pattern, using neutron reflectometry, we are able to map the surface-normal density distribution of the patterned silicon, the penetration of water into the pattern, and the distribution of a deposited film inside and outside of the etched holes. In this stud; 1,2-dilauroyl-sn-glycero-3-phosphocholine （DLPC） single bilayers were deposited on the hydrophilic patterned surface. For bilayers deposited either by vesicle fusion （VF） or by the Langmuir-Schaefer （L-S） technique, the most consistent model found to fit the data shows that the lipids form bilayer coatings on top of the substrate as well as the bottoms of the holes in an essentially conformal fashion. However, while there is a single bilayer on the unetched silicon surface, the lipids coating the bottoms of the holes form a complex bimodal structure consistent with a rough surface produced by the etching process. This study provides insight into film transfer both outside and inside regular nanopatterned features.

Sixteen erosional surfaces are recognized in a 144-m-thick condensed package of Tertiary (Eocene-Pliocene) clinoform-toe sediments recovered at ODP Site 1073 on the New Jersey slope. Most of these surfaces are associated with significant hiatuses or extremely condensed intervals defined by Sr isotopes or biostratigraphic data, and many can be linked to sequence boundaries defined in onshore and shelf seismic studies. All surfaces define the bases of fining upward sequences; they separate clay or biogenic muds below from authigenic glauconitic sandy muds or sands above. The entire Tertiary package is thoroughly bioturbated and dominated by ichnotaxa representing softground conditions. Burrow densities, burrow preservation, and the relative importance of certain ichnotaxa vary through the Tertiary package, reflecting changes in water depth, relative degree of condensation, and associated glaucony authigenesis, all related to margin progradation. Nonetheless, when individual sequences are considered, little or no change in softground ichnofossil assemblages is recognized across bounding surfaces. However, most surfaces are marked clearly by firmground Thalassinoides, burrow systems that penetrate deeply (up to 2 m) into subjacent clays and are characterized by extremely sharp walls and coarser glauconitic fills. In shallower shelf sequences, firmground ichnofabrics develop at sequence boundaries in response to subaerial exposure and transgressive ravinement. In contrast, the Tertiary firmgrounds on the New Jersey margin formed in deep water in response to phases of rapid transgression and net erosion; consolidated mud substrates were exhumed as a result of sediment starvation and bottom-current winnowing, facilitated by bioerosion, at or near the bases of slope clinoforms. These observations extend the previously established sequence stratigraphic utility of the substrate-controlled Glossifungites ichnofacies to deeper water facies.

Sixteen erosional surfaces are recognized in a 144-m-thick condensed package of Tertiary (Eocene-Pliocene) clinoform-toe sediments recovered at ODP Site 1073 on the New Jersey slope. Most of these surfaces are associated with significant hiatuses or extremely condensed intervals defined by Sr isotopes or biostratigraphic data, and many can be linked to sequence boundaries defined in onshore and shelf seismic studies. All surfaces define the bases of fining upward sequences; they separate clay or biogenic muds below from authigenic glauconitic sandy muds or sands above. The entire Tertiary package is thoroughly bioturbated and dominated by ichnotaxa representing softground conditions. Burrow densities, burrow preservation, and the relative importance of certain ichnotaxa vary through the Tertiary package, reflecting changes in water depth, relative degree of condensation, and associated glaucony authigenesis, all related to margin progradation. Nonetheless, when individual sequences are considered, little or no change in softground ichnofossil assemblages is recognized across bounding surfaces. However, most surfaces are marked clearly by firm-ground Thalassinoides, burrow systems that penetrate deeply (up to 2 m) into subjacent clays and are characterized by extremely sharp walls and coarser glauconitic fills. In shallower shelf sequences, firmground ichnofabrics develop at sequence boundaries in response to subaerial exposure and transgressive ravinement. In contrast, the Tertiary firmgrounds on the New Jersey margin formed in deep water in response to phases of rapid transgression and net erosion; consolidated mud substrates were exhumed as a result of sediment starvation and bottom-current winnowing, facilitated by bioerosion, at or near the bases of slope clinoforms. These observations extend the previously established sequence stratigraphic utility of the substrate-controlled Glossifungites ichnofacies to deeper water facies.