Article
Meteorology & Atmospheric Sciences
Darin Comeau, Xylar S. Asay-Davis, Carolyn Branecky Begeman, Matthew J. Hoffman, Wuyin Lin, Mark R. Petersen, Stephen F. Price, Andrew F. Roberts, Luke P. Van Roekel, Milena Veneziani, Jonathan D. Wolfe, Jeremy G. Fyke, Todd D. Ringler, Adrian K. Turner
Summary: In this study, the configuration of the U.S. Department of Energy's Energy Exascale Earth System Model (E3SM) v1.2 for the cryosphere is documented. The model includes the simulation and parameterization of Antarctic ice-shelf basal melting and iceberg melt, aiming to accurately represent the mass loss processes of the Antarctic Ice Sheet. The results show that the ocean/ice shelf interactions are highly sensitive to the ocean state, and including a spatially dependent parameterization can reduce biases in water mass properties. The E3SM model produces realistic ice-shelf basal melt rates across the continent that are consistent with observations.
JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS
(2022)
Article
Environmental Sciences
Kazuya Kusahara
Summary: Recent observations have shown changes in the Antarctic sea ice and ice shelf over the years. Analysis from an ocean-sea ice-ice shelf model reveals a clear anti-correlation between Antarctic sea ice extent and ice shelf basal melting, indicating that the summer sea ice extent can act as a proxy for predicting Antarctic coastal water masses and ice shelf melting.
ENVIRONMENTAL RESEARCH LETTERS
(2021)
Article
Geosciences, Multidisciplinary
Ruth Moorman, Andrew F. Thompson, Earle A. Wilson
Summary: The melt rates of West Antarctic ice shelves in the Amundsen Sea are influenced by decadal variations in the volume of warm water at their outlets, which are generally attributed to wind-driven variations in warm water transport. However, this study introduces a simple model that suggests interannual variations in coastal polynya buoyancy forcing can also generate large decadal-scale variations in thermocline depth, even with a fixed supply of warm water from the shelf-break. This model demonstrates feedbacks between basal melt rates and ice front stratification strength, capturing observed variations in near-coast thermocline depth and stratification strength, and proposing an alternative mechanism for warm water volume changes compared to wind-driven theories.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Yoshihiro Nakayama, Chad A. Greene, Fernando S. Paolo, Vigan Mensah, Hong Zhang, Haruhiko Kashiwase, Daisuke Simizu, Jamin S. Greenbaum, Donald D. Blankenship, Ayako Abe-Ouchi, Shigeru Aoki
Summary: Research suggests that the Antarctic Slope Current (ASC) plays a blocking role in intrusions of warm modified Circumpolar Deep Water (mCDW) towards the Totten ice shelf (TIS) region, with weakening of the ASC leading to enhanced on-shelf intrusions. Additionally, heat intrusions onto the TIS continental shelf are not influenced by off-shelf warming but rather by coastal freshening, indicating a positive feedback mechanism where ice melt and freshening upstream could trigger a chain reaction of increased melt and further coastal freshening.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Environmental Sciences
Taekyun Kim, Ji-Seok Hong, Emilia Kyung Jin, Jae-Hong Moon, Sang-Keun Song, Won Sang Lee
Summary: Due to limited observations, this study investigates the characteristics of ocean-driven melting beneath the Nansen Ice Shelf using a numerical model and explores the effects of tides and cavity geometry on the melt rates.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Oceanography
Daniel N. Goldberg, Andrew G. Twelves, Paul R. Holland, Martin G. Wearing
Summary: Little is known about Antarctic subglacial hydrology, but it is believed that subglacial runoff enhances submarine melt locally through buoyancy effects. This study examines the effects of runoff on sea ice and oceanography on the Continental Shelf, and finds that runoff enhances localized melt and reduces summer sea ice volume. Runoff-driven melt and circulation may be an important missing process in regional Antarctic ocean models.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)
Article
Multidisciplinary Sciences
Madelaine Gamble Rosevear, Bishakhdatta Gayen, Benjamin Keith Galton-Fenzi
Summary: The study highlights the importance of double-diffusive convection in controlling ice shelf melt rates and oceanic mixed layer properties in warm and low-velocity cavity environments beneath ice shelves. The findings suggest that current ice-ocean parameterizations underestimate melt rates by neglecting the role of double-diffusive convection, which is identified as a primary process in the oceanic melting of ice shelves.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Environmental Sciences
Fabio Boeira Dias, Stephen R. R. Rintoul, Ole Richter, Benjamin Keith Galton-Fenzi, Jan D. D. Zika, Violaine Pellichero, Petteri Uotila
Summary: Water mass transformation (WMT) around the Antarctic margin plays a crucial role in various aspects related to Antarctica, including formation of Antarctica Bottom Water, global meridional overturning circulation, ocean-ice shelf exchange, ice sheet stability, and sea level rise. However, the mechanisms controlling the rate of WMT in the Antarctic shelf remain poorly understood due to limited observations and the inability of climate models to simulate them accurately. This study utilized an ocean-ice shelf model to investigate the contribution of different factors to WMT on the continental shelf. The results highlight the significance of resolving small-scale features, topography, and including tidal forcing in order to adequately represent water mass transformations that influence the global overturning circulation.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Multidisciplinary Sciences
Yidongfang Si, Andrew L. Stewart, Ian Eisenman
Summary: The Antarctic Slope Front (ASF) is a strong gradient in water mass properties near the Antarctic margins, separating warm water from the Antarctic ice sheet. Heat transport across the ASF plays a crucial role in Earth's climate, affecting ice shelves melting, bottom water formation, and global meridional overturning circulation. Previous studies using low-resolution global models have contradictory findings on the impact of additional meltwater on heat transport toward the Antarctic continental shelf, and it remains unclear whether meltwater enhances shoreward heat transport or isolates the continental shelf from the open ocean. In this study, eddy- and tide-resolving simulations are used to investigate heat transport across the ASF, and it is found that freshening of coastal waters increases shoreward heat flux, indicating a positive feedback in a warming climate: increased meltwater leads to greater shoreward heat transport, causing further ice shelf melting.
Article
Environmental Sciences
Tetsuya P. Tamura, Daiki Nomura, Daisuke Hirano, Takeshi Tamura, Masaaki Kiuchi, Gen Hashida, Ryosuke Makabe, Kazuya Ono, Shuki Ushio, Kaihe Yamazaki, Yoshihiro Nakayama, Keigo D. Takahashi, Hiroko Sasaki, Hiroto Murase, Shigeru Aoki
Summary: This study examined the impacts of basal melting of the Antarctic ice sheet and biological productivity on biogeochemical processes in Antarctic coastal waters. Results showed that physical oceanographic processes mainly influenced the distributions of dissolved inorganic carbon (DIC), total alkalinity (TA), and nutrient concentrations. However, photosynthesis and dilution by meltwater from sea ice and the ice shelf base decreased DIC, TA, and nutrient concentrations in surface water near the ice front. Iron delivered by buoyancy-driven upwelling, basal ice shelf meltwater, and sea ice meltwater stimulated photosynthesis in surface water.
GLOBAL BIOGEOCHEMICAL CYCLES
(2023)
Article
Geosciences, Multidisciplinary
Max Thomas, Jeff K. Ridley, Inga J. Smith, David P. Stevens, Paul R. Holland, Shona Mackie
Summary: In this research, a coupled climate model is used to investigate the feedbacks between subsurface continental shelf ocean temperatures and Antarctic glacial melt. The model is forced with SSP5-8.5 and an uncoupled projection of basal melt and calving fluxes. The results show that additional glacial melt at depth cools certain seas, suggesting a negative feedback on basal melt. However, in other regions, additional glacial melt increases temperatures at the continental shelf sea floor, suggesting a positive feedback.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geochemistry & Geophysics
Mingliang Liu, Zemin Wang, Baojun Zhang, Shuang Wu, Jiachun An
Summary: This study accurately identifies the distribution location of Antarctic Ice Shelf Basal Channel (AISBC) using various data sources and analyzes the main formation mechanism of basal channels in different sea regions. The research results provide scientific reference data for studying ice shelf stability.
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS
(2023)
Article
Multidisciplinary Sciences
P. A. Reid, R. A. Massom
Summary: Loss of protective sea-ice buffer in Antarctica has led to increased exposure of the coastal environment to open ocean and waves, which has significant effects on ice-shelf stability, coastal erosion, ice-ocean-atmosphere interactions, and shallow benthic ecosystems. Researchers have introduced a climate and environmental metric called Coastal Exposure Length, which measures the daily changes and variability in the length and occurrence of unprotected coastline in Antarctica. The study found that around 50% of Antarctica's 17,850-km coastline had no sea ice offshore each summer, with variations in exposure levels across regions and seasons. From 1979 to 2020, the annual maximum length of coastal exposure decreased by approximately 30 km per year.
NATURE COMMUNICATIONS
(2022)
Editorial Material
Geosciences, Multidisciplinary
Robert D. Larter
Summary: Ice shelves in Antarctica restrict the outflow of glaciers and limit the contribution to sea-level rise. However, past events have shown their vulnerability to melting, making it the largest uncertainty in predicting future sea-level rise. An analysis of ice-shelf roughness variations suggests a potential measure of the impact of basal melting on the structural integrity of ice shelves. Further research is needed to explore other contributing factors.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Environmental Sciences
Ji-Hoon Oh, Kyung Min Noh, Hyung-Gyu Lim, Emilia Kyung Jin, Sang-Yoon Jun, Jong-Seong Kug
Summary: This study examines the impacts of Antarctic meltwater on surface phytoplankton biomass in the Southern Ocean. It finds that the enhanced stratification due to the meltwater leads to changes in surface nutrient concentrations, particularly a decrease in nitrate concentration and an increase in dissolved iron concentration. These changes can shift the nutrient availability in the ocean and impact the biomass of phytoplankton.
ENVIRONMENTAL RESEARCH LETTERS
(2022)
Article
Fisheries
Mark G. Hadfield, Craig L. Stevens
Summary: The study used a baroclinic, tide-resolving ocean model to hindcast currents in Cook Strait, finding that the model accurately reproduced observed tidal and subtidal currents as well as volume flux. Results suggest the true 3-year mean volume flux through Cook Strait is 0.42 +/- 0.08 Sv, with tidal volume flux amplitude at 4.68 Sv (M2) and subtidal fluctuations at a standard deviation of 0.62 Sv. The impact of wind on volume flux fluctuations was also explored, showing a high correlation (r = 0.93) with subtidal fluctuations from the baroclinic model, indicating wind-generation of these fluctuations.
NEW ZEALAND JOURNAL OF MARINE AND FRESHWATER RESEARCH
(2021)
Article
Multidisciplinary Sciences
Verity C. B. Forbes, Katharine J. M. Dickinson, Christina L. Hulbe
Summary: This study examines the development of the New Zealand Department of Conservation (DOC) in response to changes in government policy and analyzes gender participation patterns using social-ecological systems theory. The research reveals that gender equity gains within DOC have varied at different levels, resulting in disparities in gender representation between leadership and lower ranks. Additionally, changes in the organisation's core business have different impacts on male and female representation in the workforce.
JOURNAL OF THE ROYAL SOCIETY OF NEW ZEALAND
(2022)
Article
Multidisciplinary Sciences
Clara Martinez-Perez, Chris Greening, Sean K. Bay, Rachael J. Lappan, Zihao Zhao, Daniele De Corte, Christina Hulbe, Christian Ohneiser, Craig Stevens, Blair Thomson, Ramunas Stepanauskas, Jose M. Gonzalez, Ramiro Logares, Gerhard J. Herndl, Sergio E. Morales, Federico Baltar
Summary: Using a multi-omics approach, this study provides insights into the microbial communities beneath the Ross Ice Shelf in coastal Antarctica. The findings reveal a taxonomically distinct microbial community adapted to a highly oligotrophic marine environment, with aerobic lithoautotrophic archaea and bacteria driving the production of new organic carbon, and aerobic organoheterotrophic bacteria capable of degrading complex organic carbon substrates.
NATURE COMMUNICATIONS
(2022)
Article
Geosciences, Multidisciplinary
Christian Ohneiser, Christina L. L. Hulbe, Catherine Beltran, Christina R. R. Riesselman, Christopher M. M. Moy, Donna B. B. Condon, Rachel A. A. Worthington
Summary: This study reveals that the advance and retreat of the Ross Ice Shelf in Antarctica, as well as the West Antarctic Ice Sheet, were primarily influenced by 41,000-year-long obliquity cycles. The study also suggests that high-latitude insolation-controlled Southern Ocean heat uptake continued to be the main driver of Antarctic glaciations until at least 400,000 years ago. This research reconciles the mismatch between the inferred glacial cycles and the insolation record.
Article
Geosciences, Multidisciplinary
David E. Gwyther, Christine F. Dow, Stefan Jendersie, Noel Gourmelen, Benjamin K. Galton-Fenzi
Summary: Subglacial freshwater discharge from beneath Antarctic glaciers has a significant impact on ice shelf basal melting. The difficulty in directly observing this process highlights the importance of modeling. By injecting subglacial discharge into an ocean model, we show that it increases melting in the outflow region, driven by the formation of a buoyant plume rather than heat addition, and has far-reaching effects. Subglacial hydrology-induced basal melting is crucial for ice shelf stability but often overlooked in ice-ocean models.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
J. D. Lawrence, P. M. Washam, C. Stevens, C. Hulbe, H. J. Horgan, G. Dunbar, T. Calkin, C. Stewart, N. Robinson, A. D. Mullen, M. R. Meister, B. C. Hurwitz, E. Quartini, D. J. G. Dichek, A. Spears, B. E. Schmidt
Summary: Observations from a remotely operated underwater vehicle reveal crevasse refreezing and fine-scale variability in ice and ocean structure at Kamb Ice Stream grounding line in West Antarctica. The findings highlight the importance of understanding ice, ocean, and seafloor interactions in remote regions and the impact of grounding-line migration on ice-sheet mass balance and sea level. These observations provide insight into past grounding-line retreat and ongoing ice-ocean interactions.
Article
Geochemistry & Geophysics
R. J. M. Baxter, J. D. L. White, C. Ohneiser, M. Brenna
Summary: Information about birth and early eruptions of composite volcanoes is limited, but by applying AMS techniques, researchers have retrieved information about the earliest known submarine eruptive center of the Dunedin Volcano. By examining the AMS fabrics of the deposits, they were able to triangulate the vent site location, despite the chaotic nature of the rapidly aggraded deposits. This method provides insights into the depositional processes of both subaqueous and subaerial volcanic currents.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geosciences, Multidisciplinary
Olivia J. Truax, Bette L. Otto-Bliesner, Esther C. Brady, Craig L. Stevens, Gary S. Wilson, Christina R. Riesselman
Summary: Our study investigates the variability in Antarctic climate and sea ice extent during the last millennium and finds a dipole pattern with cooling over most of Antarctica and warming east of the Antarctic Peninsula. We did not find a clear link between this dipole pattern and baseline shifts in the Southern Annular Mode and El Nino-Southern Oscillation proposed by some paleoclimate reconstructions.
Article
Meteorology & Atmospheric Sciences
Madelaine Rosevear, Benjamin Galton-Fenzi, Craig Stevens
Summary: Ocean-driven melting of Antarctic ice shelves leads to loss of grounded ice from the Antarctic continent. However, the processes governing ice shelf melting are not well understood, contributing to uncertainty in projecting sea level rise. This study presents direct measurements of basal melting from the Amery Ice Shelf using novel methods. The results show seasonal variation in melt rate and indicate that current speed-dependent parameterisations tend to overestimate melting.
Article
Environmental Sciences
Drew M. Friedrichs, Jasmin B. T. McInerney, Holly J. Oldroyd, Won Sang Lee, Sukyoung Yun, Seung-Tae Yoon, Craig L. Stevens, Christopher J. Zappa, Christine F. Dow, Derek Mueller, Oscar Sepulveda Steiner, Alexander L. Forrest
Summary: Antarctica's ice shelves play a critical role in slowing the loss of terrestrial ice into the ocean and limiting sea level rise. Understanding the coastal ocean mechanics and ice-ocean interaction is crucial for predicting the future state of ice shelves. A recent study reveals the presence of a large eddy in the Nansen Ice Shelf, which dominated the local ocean circulation and promoted the upwelling of cold ice shelf water and deepening of warm surface water. This eddy-driven heat transport could enhance summertime melt in regions with shallower ice draft.
COMMUNICATIONS EARTH & ENVIRONMENT
(2022)
Article
Meteorology & Atmospheric Sciences
Catherine O. de Burgh-Day, Claire M. Spillman, Grant Smith, Craig L. Stevens
Summary: This study assesses the forecast skill of the Australian Bureau of Meteorology's seasonal prediction system in predicting extreme marine heat events in key aquaculture regions around New Zealand. The results show that the model has skill in predicting these events, which can enable marine operators to mitigate potential losses.
JOURNAL OF SOUTHERN HEMISPHERE EARTH SYSTEMS SCIENCE
(2022)