Abyssal ocean overturning slowdown and warming driven by Antarctic meltwater

Nature, Journal Year: 2023, Volume and Issue: 615(7954), P. 841 - 847

Published: March 29, 2023

Language: Английский

---

Historical and Future Projected Warming of Antarctic Shelf Bottom Water in CMIP6 Models

Geophysical Research Letters, Journal Year: 2021, Volume and Issue: 48(10)

Published: April 19, 2021

Abstract Understanding warming on the Antarctic shelf is critical for projecting changes in ice shelves and sheets. Here we assess Shelf Bottom Water (ASBW) temperature mean‐state trends CMIP6 models. While models do not resolve shelves, future water will impact vulnerability. The multi‐model mean zonal structure ASBW spatial pattern resemble observations, although there considerable spread across a warm bias. projects an average of 0.36°C (interdecile range 0.07°C–0.60°C) under SSP245 0.62°C 0.16°C–0.95°C) SSP585 by 2100, emphasizing influence emissions have around Antarctica. Changes transport Circumpolar Deep onto associated with Southern Annular Mode, as well warming, are predicted to conspire future.

Language: Английский

---

Simulations With the Marine Biogeochemistry Library (MARBL)

Journal of Advances in Modeling Earth Systems, Journal Year: 2021, Volume and Issue: 13(12)

Published: Nov. 15, 2021

Abstract The Marine Biogeochemistry Library (MARBL) is a prognostic ocean biogeochemistry model that simulates marine ecosystem dynamics and the coupled cycles of carbon, nitrogen, phosphorus, iron, silicon, oxygen. MARBL component Community Earth System Model (CESM); it supports flexible configuration multiple phytoplankton zooplankton functional types; also portable, designed to interface with circulation models. Here, we present scientific documentation MARBL, describe its in CESM2 experiments included Coupled Intercomparison Project version 6 (CMIP6), evaluate performance against number observational data sets. present‐day air‐sea CO 2 flux many aspects carbon cycle good agreement observations. However, simulated integrated uptake anthropogenic weak, which link poor thermocline ventilation, feature evident chlorofluorocarbon distributions. This contributes larger‐than‐observed oxygen minimum zones. Moreover, radiocarbon distributions show deep North Pacific extremely sluggish, yielding extensive depletion nutrient trapping at depth. Surface macronutrient biases are generally positive low latitudes negative high latitudes. globally net primary production (NPP) 48 Pg C yr −1 particulate export 100 m 7.1 . impacts climate change include an increase NPP, but substantial declines Atlantic. Particulate projected decline globally, attributable decreasing efficiency associated changes community composition.

Language: Английский

---

The Antarctic contribution to 21st-century sea-level rise predicted by the UK Earth System Model with an interactive ice sheet

˜The œcryosphere, Journal Year: 2022, Volume and Issue: 16(10), P. 4053 - 4086

Published: Oct. 7, 2022

Abstract. The Antarctic Ice Sheet will play a crucial role in the evolution of global mean sea level as climate warms. An interactively coupled and ice sheet model is needed to understand impacts ice–climate feedbacks during this evolution. Here we use two-way coupling between UK Earth System Model BISICLES (Berkeley Initiative for Climate at Extreme Scales) dynamic investigate interactions under two change scenarios. We perform ensembles SSP1–1.9 SSP5–8.5 (Shared Socioeconomic Pathway) scenario simulations 2100, which believe are first such with that include atmosphere ocean models Greenland sheets. focus our analysis on latter. In simulations, shelf basal melting grounded mass loss from generally lower than present rates entire simulation period. contrast, responses forcing strong. By end 21st century, these feature order-of-magnitude increases Ross Filchner–Ronne shelves, caused by intrusions masses warm water. Due slow response drawdown, strong does not cause substantial increase discharge simulations. surface balance shows pattern decrease increased melting, ice, snowfall. Despite snowfall dominates budget leading an ensemble contribution fall 22 mm 2100 scenario. hypothesise signal would revert sea-level rise longer timescales, thinning. These results demonstrate need fully reducing uncertainty Sheet.

Language: Английский

---

PARASO, a circum-Antarctic fully coupled ice-sheet–ocean–sea-ice–atmosphere–land model involving f.ETISh1.7, NEMO3.6, LIM3.6, COSMO5.0 and CLM4.5

Geoscientific model development, Journal Year: 2022, Volume and Issue: 15(2), P. 553 - 594

Published: Jan. 25, 2022

Abstract. We introduce PARASO, a novel five-component fully coupled regional climate model over an Antarctic circumpolar domain covering the full Southern Ocean. The state-of-the-art models used are fast Elementary Thermomechanical Ice Sheet (f.ETISh) v1.7 (ice sheet), Nucleus for European Modelling of Ocean (NEMO) v3.6 (ocean), Louvain-la-Neuve sea-ice (LIM) (sea ice), COnsortium Small-scale MOdeling (COSMO) v5.0 (atmosphere) and its CLimate Mode (CLM) v4.5 (land), which here run at horizontal resolution close to 1/4∘. One key feature this tool resides in two-way coupling interface representing ocean–ice-sheet interactions, through explicitly resolved ice-shelf cavities. impact atmospheric processes on ice sheet is also conveyed computed COSMO-CLM–f.ETISh surface mass exchange. In technical paper, we briefly each model's configuration document developments that were carried out order establish PARASO. new offline-based NEMO–f.ETISh thoroughly described. Our include tiling approach combine open-ocean sea-ice-covered cells within COSMO, was required make relevant context simulations polar regions. present results from 2000–2001 2-year experiment. PARASO numerically stable operational. simulation conducted without fine tuning reproduced main expected features, although remaining systematic biases provide perspectives further adjustment development.

Language: Английский

---

Seasonality of the Meridional Overturning Circulation in the subpolar North Atlantic

Communications Earth & Environment, Journal Year: 2023, Volume and Issue: 4(1)

Published: May 25, 2023

Abstract Understanding the variability of Atlantic Meridional Overturning Circulation is essential for better predictions our changing climate. Here we present an updated time series (August 2014 to June 2020) from in Subpolar North Program. The 6-year allows us observe seasonality subpolar overturning and meridional heat freshwater transports. peaks late spring reaches a minimum early winter, with peak-to-trough range 9.0 Sv. seasonal timing can be explained by winter transformation export dense water, modulated seasonally varying Ekman transport. Furthermore, over 55% total transport its seasonality, largely owing dynamics. Our results provide first observational analysis highlight important contribution observed date.

Language: Английский

---

The mixed-layer depth in the Ocean Model Intercomparison Project (OMIP): impact of resolving mesoscale eddies

Geoscientific model development, Journal Year: 2023, Volume and Issue: 16(13), P. 3849 - 3872

Published: July 12, 2023

Abstract. The ocean mixed layer is the interface between interior and atmosphere or sea ice plays a key role in climate variability. It thus critical that numerical models used studies are capable of good representation layer, especially its depth. Here we evaluate mixed-layer depth (MLD) six pairs non-eddying (1∘ grid spacing) eddy-rich (up to 1/16∘) from Ocean Model Intercomparison Project (OMIP), forced by common atmospheric state. For model evaluation, use an updated MLD dataset computed observations using OMIP protocol (a constant density threshold). In winter, low-resolution exhibit large biases deep-water formation regions. These reduced but not uniformly across improvement most noticeable mode-water regions Northern Hemisphere. Results Southern more contrasted, with either sign remaining at high resolution. models, mesoscale eddies control spatial variability winter. Contrary hypothesis deepening anticyclones would make larger globally, tend have shallower latitudes than coarser do. addition, our study highlights sensitivity computation choice reference level spatio-temporal sampling, which motivates new recommendations for future intercomparison projects.

Language: Английский

---

Pathways and Timescales of Connectivity Around the Antarctic Continental Shelf

Journal of Geophysical Research Oceans, Journal Year: 2023, Volume and Issue: 128(2)

Published: Jan. 30, 2023

Abstract The Antarctic Slope Current (ASC) and Coastal advect heat, freshwater, nutrients, biological organisms westward around the margin, providing a connective link between different sectors of continental shelf. Yet strength pathways connectivity continent, timescales advection, remain poorly understood. We use daily velocity fields from global high‐resolution ocean‐sea ice model, combined with Lagrangian particle tracking, to shed light on these improve our understanding circumpolar Antarctica. Virtual particles were released along vertical transects over shelf every 5 days for year tracked forward in time 21 years. Analysis resulting trajectories highlights that West sector has widespread all regions Advection continent is typically rapid peak transit times 1–5 years travel 90° longitude downstream. ASC plays key role driving East Antarctica Weddell Sea, while controls Antarctica, eastern Peninsula, east Prydz Bay. Connectivity impeded two main locations, namely, tip Peninsula Cape Adare Ross where significant export water found. These findings help understand locations which anomalies, such as meltwater Ice Sheet, can be redistributed

Language: Английский

---

The representation of alkalinity and the carbonate pump from CMIP5 to CMIP6 Earth system models and implications for the carbon cycle

Biogeosciences, Journal Year: 2023, Volume and Issue: 20(7), P. 1195 - 1257

Published: April 3, 2023

Abstract. Ocean alkalinity is critical to the uptake of atmospheric carbon in surface waters and provides buffering capacity towards associated acidification. However, unlike dissolved inorganic (DIC), not directly impacted by anthropogenic emissions. Within context projections future ocean potential ecosystem impacts, especially through Coupled Model Intercomparison Projects (CMIPs), representation main driver its distribution interior, calcium carbonate cycle, have often been overlooked. Here we track changes from CMIP5 CMIP6 with respect Earth system model (ESM) pump which depletes biological production releases it at depth export dissolution. We report an improvement ESMs relative those CMIP5, simulating lower concentrations, increased meridional gradient enhanced global vertical gradient. This can be explained part increase (CaCO3) for some ESMs, redistributes strengthens water column. were able constrain a particulate (PIC) estimate 44–55 Tmol yr−1 100 m match observed alkalinity. Reviewing CaCO3 cycle across CMIP5/6, find substantial range parameterizations. While all biogeochemical models currently represent pelagic calcification, they do so implicitly, benthic calcification. In addition, most simulate marine calcite but aragonite. CMIP6, certain groups complexity simulated production, sinking, dissolution sedimentation. this insufficient explain overall representation, therefore likely result biogeochemistry tuning or ad hoc Although modellers aim balance budget order limit drift under pre-industrial conditions, varying assumptions related closure and/or initialization procedure influence uptake. For instance, many models, burial are independent seawater saturation state, when considered, sensitivities substantial. As such, impact acidification on pump, turn uptake, potentially underestimated current insufficiently constrained.

Language: Английский

---

Wind– and Sea‐Ice–Driven Interannual Variability of Antarctic Bottom Water Formation

Journal of Geophysical Research Oceans, Journal Year: 2023, Volume and Issue: 128(6)

Published: June 1, 2023

Abstract Antarctic Bottom Water (AABW) is a major component of the global overturning circulation, originating around continental margin. In recent decades AABW has both warmed and freshened, but there also evidence large interannual variability. The causes this underlying variability are not yet fully understood, in part due to lack ocean air‐sea‐ice flux measurements region. Here, we simulate formation export from 1958 2018 using global, eddying ocean–sea‐ice model which four regions transports agree reasonably well with observations. simulated exhibits strong correlated between different regions. Reservoirs very dense waters at depth Weddell Ross Seas following 1–2 years surface water mass transformation can lead higher for up decade. Prydz Bay Adélie Coast contrast, reservoirs do persist beyond 1 year attribute narrower shelf extent East main factor controlling high weaker easterly winds, reduce sea ice import into region, leaving increased areas open primed air‐sea buoyancy loss convective overturning. Our study highlights all regions, potential implications interpreting trends observational data only limited duration coverage.

Language: Английский

---