About

Harriet Lau is an Assistant Professor in the Department of Earth, Environmental & Planetary Sciences at Brown University. Her research group explores global-scale geodynamical problems across many time scales, including solid Earth and ocean tides (hours to years), deformation of the Earth due to the melting of large Pleistocene ice sheets (years to tens of thousands of years), and mantle convection, which drives plate tectonics (millions to billions of years). Her work aims to coherently characterize the Earth's behavior across these vastly different time scales and to learn fundamental insights about our planet. Harriet Lau has contributed to understanding Earth's internal processes, including recent research on Earth's core and mantle interactions, early tectonic activity, and the Earth's magnetic field. She has presented at TEDx New England on Earth's natural cycles and rhythms, and her work has been featured in various scientific discussions and publications. She received the Packard Fellowship for Science and Engineering in 2022 in recognition of her outstanding work on the relationships between Earth's deformation and climate.

Research topics

• Computer Science
• Geology
• Physics
• Meteorology
• Engineering
• Astronomy
• Geophysics
• Seismology
• Geography
• Telecommunications
• Geodesy
• Oceanography
• Environmental science
• Aerospace engineering
• Earth science
• Astrobiology

Selected publications

• West Antarctic Ice Retreat Temporarily Halted with Transient Rheology in Future Climate Projections

  2026-04-24

  articleOpen access

  Abstract. Projections of sea-level change and Antarctic Ice Sheet (AIS) stability under anthropogenic climate change hinge upon accurately describing physical feedbacks that link ice dynamics (marine and terrestrial) with the gravitational, rotational and deformational response of the solid Earth to ice and ocean loading changes. In turn, the rate of AIS melting can lower the rate of global mean temperature rise, by promoting sea ice growth and amplifying Earth’s albedo. The marine West Antarctic Ice Sheet (WAIS) is vulnerable to runaway grounding line retreat. However, the rapid viscoelastic rebound of the bedrock in response to ice retreat has been shown to stabilize its grounding line, aided by the low-viscosity mantle beneath the WAIS. Such bedrock deformation is typically modelled with idealized Maxwell viscoelasticity, despite that rock deformation experiments show that additional “transient” creep mechanisms occur over societally relevant (~decadal-centennial) timescales that are missing from the Maxwell model. Here, we simulate future AIS evolution, coupled with self-consistent solid Earth deformation and sea level change, for various emissions scenarios (RCP 2.6, 4.5, 8.5), incorporating transient deformation. This more complete treatment of solid Earth deformation delays grounding line retreat as compared to Maxwell projections, with differences of tens of kilometres persisting for decades at Pine Island and Thwaites Glaciers. Though transient deformation slows glacier retreat, it is unable to prevent the bulk of ice loss and sea-level rise on longer, centennial timescales. Even still, deviations in AIS meltwater flux with transient deformation could affect the pace of global temperature rise in climate model predictions.

  PublisherOA PDFDOI

• Supplementary material to "West Antarctic Ice Retreat Temporarily Halted with Transient Rheology in Future Climate Projections"

  2026-04-24

  article
  PublisherDOI

• Thermal Evolution of the Moon Dominated by the Earth

  Zenodo (CERN European Organization for Nuclear Research) · 2025-07-23

  articleOpen access
  PublisherDOI

• True and Apparent Polar Wander From Sluggish to Active Lid Tectonics

  Journal of Geophysical Research Solid Earth · 2025-09-01

  articleOpen access1st authorCorresponding

  Abstract It has been proposed that to satisfy a wide range of geological observations, early Earth mantle convection operated in “sluggish‐lid” tectonics before transitioning to modern‐day, “active‐lid” tectonics. The former is the result of a weaker asthenosphere relative to the latter and manifests itself in a partially decoupled plate‐mantle system. This transition is required to produce reasonable apparent polar wander (APW) plate velocities over Earth history. Since these tectonic regimes are dictated by the thermo‐mechanical structure of the mantle, they should also influence true polar wander (TPW). Here, we explore the relative importance of TPW within a mantle that transitions from sluggish‐to active‐lid tectonics to provide some context on how to interpret paleomagnetic observations over Earth history. We find that TPW rates are faster when Earth's mantle operates in sluggish‐lid tectonics than active‐lid, contrary to previous results that appear to only be appropriate for active‐lid TPW. We also find that if subduction initiated during sluggish‐lid tectonics, this could also lead to high, intermittent rates of TPW.

  PublisherOA PDFDOI

• Meltwater Pulse 1A sea-level-rise patterns explained by global cascade of ice loss

  Nature Geoscience · 2025-02-18 · 5 citations

  article
  PublisherDOI

• Tidal Heating of the Lunar Magma Ocean: Reconciling an Old Moon with a Young Solidification

  arXiv (Cornell University) · 2025-11-25

  preprintOpen access

  The timing of the Moon's formation is fundamental to understanding the early Earth-Moon system. Ages of lunar magma ocean (LMO) crystallization have long been regarded as a key proxy for that event. Yet returned lunar sample ages cluster near the relatively young age of ~4.35 billion years ago (Ga). These ages are commonly interpreted as recording either a young-Moon formation age or later thermal resetting. Here we show that, for an old Moon (>4.5 Ga), the ~4.35 Ga age cluster can instead arise naturally from early LMO thermal evolution under Earth's tidal forcing. We identify tidal heating within a partially molten LMO as a major internal heat source. It offsets much of the early heat loss and maintains a long-lived high-energy state for >150 million years. As crystallization proceeded, this stable state was ultimately lost through the rapid collapse of tidal heating. The last stages of LMO solidification were compressed into a short interval near ~4.35 Ga. The tidal heat source decouples Moon formation from final LMO solidification. As an outcome of LMO evolution, we predict asymmetric late-stage crystallization between the lunar nearside and farside, potentially linking tidally modulated LMO evolution to the long-term lunar dichotomy.

  PublisherOA PDFDOI

• Thermal Evolution of the Moon Dominated by the Earth

  Zenodo (CERN European Organization for Nuclear Research) · 2025-07-23

  articleOpen access
  PublisherDOI

• Towards a Quantitative Assessment of the Impact of Transient Mantle Rheology on Future Antarctic Ice-Sheet Stability

  2025-03-15

  preprintOpen accessSenior authorCorresponding

  Mass transfer between the cryosphere and oceans leads to sea-surface height and topography changes whose timescales, amplitudes, and spatial patterns are controlled by mantle viscoelasticity. This ‘glacial isostatic adjustment’ (GIA) can slow or halt retreat of unstable marine-based ice sheets since ice loss induces gravitational sea-surface lowering and bedrock rebound, reducing water depths around ice-sheet margins and lowering their exposure to melting by warm ocean currents. Despite widespread recognition of this solid Earth–ice-sheet feedback, it has often been assumed that Earth’s mantle is too viscous for GIA to have a measurable impact on ice-sheet dynamics over the next few centuries, with many ice-sheet models used in state-of-the-art intercomparison projects assuming either a rigid bed or millennial viscoelastic bedrock deformation timescales. However, GPS bedrock displacement timeseries suggest very low mantle viscosities exist beneath vulnerable regions of the West Antarctic Ice Sheet (~1017–1019 Pa s), implying that bedrock elevations are responding to modern melting on annual-to-decadal timescales, i.e., fast enough to have significant impact on ice-sheet stability over the coming centuries. Interestingly, GPS-inferred viscosities obtained in the same regions, but from bedrock responses to longer-timescale (102 –105-yr) deglacial signals, are at ~10–100 times larger. This result suggests the low effective viscosities obtained for modern signals reflect the operation of transient deformation mechanisms. If confirmed, this transience would have major ramifications for our understanding of future Antarctic ice-sheet stability, since it would introduce a negative feedback whereby mantle viscosities and bedrock uplift rates scale with ice mass loss rates, limiting the speed of subsequent grounding line retreat. Here, we first test whether observed loading-timescale-dependence of GPS-inferred mantle viscosities can be explained using experimentally constrained parameterisations of transient rock deformation across seismic to convective timescales. This analysis is carried out by calibrating these thermomechanical parameterisations for individual seismic tomographic models using both geophysical and experimental observations. Importantly, by adopting a probabilistic inverse method we evaluate parametric uncertainties and propagate them into our estimates of timescale-dependent 3D mantle viscosity. We find that transient and steady-state viscosities predicted by our optimal parameterisations can simultaneously explain the short- and long-timescale GPS signals recorded across the Antarctic Peninsula. Next, we integrate this thermomechanical structure into 1D transient and Maxwell viscoelastic Earth models to quantify the impact of this more complex rheology on rates of Antarctic bedrock uplift and relative sea-level change on deglaciation timescales ranging from years to millenia. Our results show that transient mechanisms have measurable impacts on all submillenial deglaciation timescales but are particularly pronounced over decadal-to-centennial intervals, producing up to ~50% more bedrock uplift and up to ~70% higher maximum uplift rates than steady-state counterparts. We conclude by presenting a thermomechanically self-consistent framework for integrating our calibrated ‘full-spectrum’ rheological parameterisations into coupled GIA–ice-sheet simulations that account for observed transient and 3D viscosity variations. We will present early results from these simulations that will ultimately enable the potential stabilising impact of transient rheology on Antarctic ice-sheet evolution to be quantified under different climatic forcing scenarios, improving projections of future barystatic sea-level change.

  PublisherDOI

• Coupled fates of Earth’s mantle and core: Early sluggish-lid tectonics and a long-lived geodynamo

  Science Advances · 2024-08-02 · 11 citations

  articleOpen accessSenior author

  Conventional Earth evolution models are unable to simultaneously reproduce two fundamental observations: the mantle's secular temperature record and a long-lived geodynamo before inner core nucleation. Today, plate tectonics efficiently cools the mantle, but if assumed to operate throughout Earth's history, past mantle temperature and plate motion become unrealistically high. Through coupled core-mantle modeling that self-consistently predicts multiple mantle convection regimes, we show that over most of the Precambrian, Earth likely operated in a distinct "sluggish-lid" tectonic mode, characterized by partial decoupling between the lithosphere and mantle. This dominant early regime is due to a hotter Earth and the presence of the asthenosphere. This mode regulates the core-mantle boundary heat flow, which powers the geodynamo before inner core nucleation. Both sluggish-lid tectonics and a long-lived dynamo demonstrate the inextricably connected paths of the core-mantle system. Moreover, our simulations simultaneously satisfy diverse geological observations and are consistent with emerging interpretations of such records.

  PublisherOA PDFDOI

• Adjoint sensitivity kernels for free oscillation spectra

  Geophysical Journal International · 2024-04-16 · 3 citations

  articleOpen access

  SUMMARY We apply the adjoint method to efficiently calculate sensitivity kernels for long-period seismic spectra with respect to structural and source parameters. Our approach is built around the solution of the frequency-domain equations of motion using the direct solution method (DSM). The DSM is currently applied within large-scale mode coupling calculations and is also likely to be useful within finite-element type methods for modelling seismic spectra that are being actively developed. Using mode coupling theory as a framework for solving both the forward and adjoint equations, we present numerical examples that focus on the spectrum close to four eigenfrequencies (the low-frequency mode, 0S2, and higher frequency modes, namely 2S2, 0S7 and 0S10 for comparison). For each chosen observable, we plot sensitivity kernels with respect to 3-D perturbations in density and seismic wave speeds. We also use the adjoint method to calculate derivatives of observables with respect to the matrices occurring within mode coupling calculations. This latter approach points towards a generalization of the two-stage splitting function method for structural inversions that does not rely on inaccurate self-coupling or group-coupling approximations. Finally, we verify through direct calculation that our sensitivity kernels correctly predict the linear dependence of the chosen observables on model perturbations. In doing this, we highlight the importance of non-linearity within inversions of long-period spectra.

  PublisherOA PDFDOI

Recent grants

• Collaborative Research: Towards a new framework for interpreting mantle deformation: integrating theory, experiments, and observations spanning seismic to convective timescales

  NSF · $452k · 2022–2027

• Constraints from multiple low frequency data on the long wavelength density structure in the deep mantle

  NSF · $596k · 2019–2023

Frequent coauthors

• J. X. Mitrovica

  46 shared

• Jacqueline Austermann

  46 shared

• Konstantin Latychev

  38 shared

• B. K. Holtzman

  Lamont-Doherty Earth Observatory

  28 shared

• M. Al Asad

  University of California, Berkeley

  24 shared

• Barbara Romanowicz

  Planetary Science Institute

  20 shared

• David Al‐Attar

  University of Cambridge

  20 shared

• Paula Koelemeijer

  19 shared

Awards & honors

• Packard Fellowship for Science and Engineering (2022)