Global mean sea level likely higher than present during the holocene.

Global mean sea-level (GMSL) change can shed light on how the Earth system responds to warming. Glaciological evidence indicates that Earth's ice sheets retreated inland of early industrial (1850 CE) extents during the Holocene (11.7-0 ka), yet previous work suggests that Holocene GMSL never surpassed early industrial levels.

Glacial isostatic adjustment reduces past and future Arctic subsea permafrost.

Sea-level rise submerges terrestrial permafrost in the Arctic, turning it into subsea permafrost. Subsea permafrost underlies ~ 1.8 million km of Arctic continental shelf, with thicknesses in places exceeding 700 m.

GIA imaging of 3-D mantle viscosity based on palaeo sea level observations - Part I: Sensitivity kernels for an Earth with laterally varying viscosity.

A key initial step in geophysical imaging is to devise an effective means of mapping the sensitivity of an observation to the model parameters, that is to compute its Fréchet derivatives or sensitivity kernel. In the absence of any simplifying assumptions and when faced with a large number of free parameters, the adjoint method can be an effective and efficient approach to calculating Fréchet derivatives and requires just two numerical simulations. In the Glacial Isostatic Adjustment problem, these consist of a forward simulation driven by changes in ice mass and an adjoint simulation driven by loads that are applied at the observation sites.

Toward a Cenozoic history of atmospheric CO.

The geological record encodes the relationship between climate and atmospheric carbon dioxide (CO) over long and short timescales, as well as potential drivers of evolutionary transitions. However, reconstructing CO beyond direct measurements requires the use of paleoproxies and herein lies the challenge, as proxies differ in their assumptions, degree of understanding, and even reconstructed values. In this study, we critically evaluated, categorized, and integrated available proxies to create a high-fidelity and transparently constructed atmospheric CO record spanning the past 66 million years.

Geodynamically corrected Pliocene shoreline elevations in Australia consistent with midrange projections of Antarctic ice loss.

The Mid-Pliocene represents the most recent interval in Earth history with climatic conditions similar to those expected in the coming decades. Mid-Pliocene sea level estimates therefore provide important constraints on projections of future ice sheet behavior and sea level change but differ by tens of meters due to local distortion of paleoshorelines caused by mantle dynamics. We combine an Australian sea level marker compilation with geodynamic simulations and probabilistic inversions to quantify and remove these post-Pliocene vertical motions at continental scale.

Constraining the contribution of the Antarctic Ice Sheet to Last Interglacial sea level.

Polar temperatures during the Last Interglacial [LIG; ~129 to 116 thousand years (ka)] were warmer than today, making this time period an important testing ground to better understand how ice sheets respond to warming. However, it remains debated how much and when the Antarctic and Greenland ice sheets changed during this period. Here, we present a combination of new and existing absolutely dated LIG sea-level observations from Britain, France, and Denmark.

Influence of reef isostasy, dynamic topography, and glacial isostatic adjustment on sea-level records in Northeastern Australia.

Understanding sea level during the peak of the Last Interglacial (125,000 yrs ago) is important for assessing future ice-sheet dynamics in response to climate change. The coasts and continental shelves of northeastern Australia (Queensland) preserve an extensive Last Interglacial record in the facies of coastal strandplains onland and fossil reefs offshore. However, there is a discrepancy, amounting to tens of meters, in the elevation of sea-level indicators between offshore and onshore sites.

The role of gravitational body forces in the development of metamorphic core complexes.

Within extreme continental extension areas, ductile middle crust is exhumed at the surface as metamorphic core complexes. Sophisticated quantitative models of extreme extension predicted upward transport of ductile middle-lower crust through time. Here we develop a general model for metamorphic core complexes formation and demonstrate that they result from the collapse of a mountain belt supported by a thickened crustal root.

Coupled influence of tectonics, climate, and surface processes on landscape evolution in southwestern North America.

The Cenozoic landscape evolution in southwestern North America is ascribed to crustal isostasy, dynamic topography, or lithosphere tectonics, but their relative contributions remain controversial. Here we reconstruct landscape history since the late Eocene by investigating the interplay between mantle convection, lithosphere dynamics, climate, and surface processes using fully coupled four-dimensional numerical models. Our quantified depth-dependent strain rate and stress history within the lithosphere, under the influence of gravitational collapse and sub-lithospheric mantle flow, show that high gravitational potential energy of a mountain chain relative to a lower Colorado Plateau can explain extension directions and stress magnitudes in the belt of metamorphic core complexes during topographic collapse.

Long-Term Earth-Moon Evolution With High-Level Orbit and Ocean Tide Models.

Tides and Earth-Moon system evolution are coupled over geological time. Tidal energy dissipation on Earth slows rotation rate, increases obliquity, lunar orbit semi-major axis and eccentricity, and decreases lunar inclination. Tidal and core-mantle boundary dissipation within the Moon decrease inclination, eccentricity and semi-major axis.

Total isostatic response to the complete unloading of the Greenland and Antarctic Ice Sheets.

The land surface beneath the Greenland and Antarctic Ice Sheets is isostatically suppressed by the mass of the overlying ice. Accurate computation of the land elevation in the absence of ice is important when considering, for example, regional geodynamics, geomorphology, and ice sheet behaviour. Here, we use contemporary compilations of ice thickness and lithospheric effective elastic thickness to calculate the fully re-equilibrated isostatic response of the solid Earth to the complete removal of the Greenland and Antarctic Ice Sheets.

Sea-level trends across The Bahamas constrain peak last interglacial ice melt.

During the last interglacial (LIG) period, global mean sea level (GMSL) was higher than at present, likely driven by greater high-latitude insolation. Past sea-level estimates require elevation measurements and age determination of marine sediments that formed at or near sea level, and those elevations must be corrected for glacial isostatic adjustment (GIA). However, this GIA correction is subject to uncertainties in the GIA model inputs, namely, Earth's rheology and past ice history, which reduces precision and accuracy in estimates of past GMSL.

Sea-level stands from the Western Mediterranean over the past 6.5 million years.

Sea-level reconstructions are important for understanding past ice sheet variability and its response to past and future warming. Here we present Neogene and Quaternary sea-level snapshots using phreatic overgrowths on speleothems (POS) from caves on Mallorca, Spain. POS are excellent sea level index points because of their clear relationship to sea level and precise U-Pb chronology.

Constraints on global mean sea level during Pliocene warmth.

Reconstructing the evolution of sea level during past warmer epochs such as the Pliocene provides insight into the response of sea level and ice sheets to prolonged warming. Although estimates of the global mean sea level (GMSL) during this time do exist, they vary by several tens of metres, hindering the assessment of past and future ice-sheet stability. Here we show that during the mid-Piacenzian Warm Period, which was on average two to three degrees Celsius warmer than the pre-industrial period, the GMSL was about 16.

Detection of a dynamic topography signal in last interglacial sea-level records.

Estimating minimum ice volume during the last interglacial based on local sea-level indicators requires that these indicators are corrected for processes that alter local sea level relative to the global average. Although glacial isostatic adjustment is generally accounted for, global scale dynamic changes in topography driven by convective mantle flow are generally not considered. We use numerical models of mantle flow to quantify vertical deflections caused by dynamic topography and compare predictions at passive margins to a globally distributed set of last interglacial sea-level markers.

Plasmon mediated confocal dark-field microscopy.

An efficient mode for scanning confocal dark-field microscopy through a thin gold film is established that takes advantage of the intermediate excitation of surface plasmons both in the excitation and in the emission process. This concept is verified by experimental investigation of the effective point-spread function, the intensity distribution of the scattered radiation and by comparison with a classical dark-field geometry. The wavelength-dependence of both the signal strength and the point-spread function are discussed.