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The role of Southern Ocean stratification in future ocean CO2 and heat uptake

Applicant Haumann Alexander
Number 186681
Funding scheme Postdoc.Mobility
Research institution Atmospheric and Oceanic Sciences Princeton University
Institution of higher education Institution abroad - IACH
Main discipline Oceanography
Start/End 01.07.2019 - 30.09.2020
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All Disciplines (4)

Discipline
Oceanography
Meteorology
Climatology. Atmospherical Chemistry, Aeronomy
Hydrology, Limnology, Glaciology

Keywords (11)

Stratification; Freshwater; Heat; Ocean; Southern Ocean; Global climate model; Climate change; CO2; Future; Carbon-dioxide; Sea ice

Lay Summary (German)

Lead
Der Austausch von Wassermassen zwischen dem oberflächennahen und tiefen Ozean hat einen grossen Einfluss auf das Klima der Erde, da durch diesen Prozess auch grosse Mengen des klimawirksamen Treibhausgases Kohlenstoffdioxid und Wärme zwischen dem Ozean und der Atmosphäre ausgetauscht werden. Dieser Austausch findet vorwiegend im Südpolarmeer statt, wo tiefes Wasser an die Oberfläche gelangt und wieder absinkt. Bei diesem Prozess spielt die vertikale Dichteschichtung der Wassersäule eine wesentliche Rolle und mögliche zukünftige Veränderungen dieser Dichteschichtung könnten zu einer Verstärkung oder Abschwächung der globalen Klimaerwärmung führen. Bis heute haben Klimamodelle jedoch Schwierigkeiten diese Dichteschichtung im Südpolarmeer realistisch abzubilden, was zu Unsicherheiten in Abschätzungen des zukünftigen Klimawandels führt.
Lay summary

Inhalt und Ziel des Forschungsprojekts

Das Ziel unseres Projektes ist es den Einfluss von Veränderungen der Dichteschichtung im Südpolarmeer auf die zukünftige Aufnahme von Kohlenstoffdioxid und Wärme besser zu verstehen und dadurch Unsicherheiten in Modellabschätzungen der zukünftigen globalen Klimaerwärmung einzuschränken. Dafür verwenden wir neue Messdaten und Analysemethoden um einerseits bestehende Modellsimulationen zu evaluieren und um andererseits die Dichteschichtung in Modellsimulationen des Südpolarmeers zu verbessern.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Unser Projekt wird neue Erkenntnisse über den Einfluss von Veränderungen im Südpolarmeer auf die zukünftige Klimaerwärmung liefern und helfen diese Prozesse in Klimamodellen zu verbessern. Unsere Arbeit zielt darauf ab die bestehenden Unsicherheiten in den zulässigen Kohlenstoffdioxidemissionen und dem Meerespiegelanstieg, welche mit dem politischen 1.5°C Ziel verbunden sind, zu verringern und somit eine bessere Planung von Anpassungsstrategien an den Klimawandel zu ermöglichen.

Direct link to Lay Summary Last update: 25.06.2019

Responsible applicant and co-applicants

Publications

Publication
Supercooled Southern Ocean Waters
Haumann F. Alexander, Moorman Ruth, Riser Stephen C., Smedsrud Lars H., Maksym Ted, Wong Annie P. S., Wilson Earle A., Drucker Robert, Talley Lynne D., Johnson Kenneth S., Key Robert M., Sarmiento Jorge L. (2020), Supercooled Southern Ocean Waters, in Geophysical Research Letters, 47(20), e2020GL090.
A NASA high-latitude salinity campaign
Drushka Kyla, Gaube Peter, Armitage Tom, Cerovecki Ivana, Fenty Ian, Fournier Severine, Gentemann Chelle, Girton James, Haumann Alexander, Lee Tony, Mazloff Matthew, Padman Laurie, Rainville Luc, Schanze Julian J., Springer Scott, Steele Michael, Thomson Jim, Wilson Earle (2020), A NASA high-latitude salinity campaign, figshare, Iasi, Romania; London, UK; Boston, USA.
Twenty first century changes in Antarctic and Southern Ocean surface climate in CMIP6
Bracegirdle Thomas J., Krinner Gerhard, Tonelli Marcos, Haumann F. Alexander, Naughten Kaitlin A., Rackow Thomas, Roach Lettie A., Wainer Ilana (2020), Twenty first century changes in Antarctic and Southern Ocean surface climate in CMIP6, in Atmospheric Science Letters, 21(9), e984.
Sea‐Ice Induced Southern Ocean Subsurface Warming and Surface Cooling in a Warming Climate
Haumann F. Alexander, Gruber Nicolas, Münnich Matthias (2020), Sea‐Ice Induced Southern Ocean Subsurface Warming and Surface Cooling in a Warming Climate, in AGU Advances, 1(2), e2019AV000.
1st Southern Ocean Regional Workshop for the UN Decade of Ocean Science for Sustainable Development Report
HofmannEileen, BiddleLouise, de BruinTaco, BrooksCassandra, CorneyStuart, HaumannAlexander, JohnstoneNadine, MazloffMatthew, MurphyEugene, ReissChristian, RussellJoellen, RosenthalHanna, SikesElisabeth (2020), 1st Southern Ocean Regional Workshop for the UN Decade of Ocean Science for Sustainable Development Report, Zenodo, Genève, Switzerland.
Recent recovery of Antarctic Bottom Water formation in the Ross Sea driven by climate anomalies
Silvano Alessandro, Foppert Annie, Rintoul Stephen R., Holland Paul R., Tamura Takeshi, Kimura Noriaki, Castagno Pasquale, Falco Pierpaolo, Budillon Giorgio, Haumann F. Alexander, Naveira Garabato Alberto C., Macdonald Alison, Recent recovery of Antarctic Bottom Water formation in the Ross Sea driven by climate anomalies, in Nature Geoscience.

Datasets

Sea-ice induced Southern Ocean subsurface warming and surface cooling in a warming climate: ROMS model data

Author Haumann, F. Alexander; Gruber, Nicolas; Münnich, Matthias
Publication date 31.03.2020
Persistent Identifier (PID) 10.5281/zenodo.3709154
Repository Zenodo
Abstract
This data set contains model output data from the regional ocean modelling system (ROMS) that was set up for the Southern Ocean (south of 24 °S; Haumann, 2016) to analyze the effects of changing surface freshwater and momentum fluxes on Southern Ocean water-mass changes over the period 1980 to 2011. All data is provided in NetCDF format. The data set contains 3 sets 40-year long model spin-up, control, and 3 perturbation simulations each. The sets differ by their model mean state to assess the effect of surface salinity biases on the results. One set of simulations are reference simulations where salinity is restored to the observed surface salinity during model spin-up, and the other two sets are simulations in which the restoring surface salinity has been altered by plus and minus 0.1 PSU, respectively. The control and perturbation simulations are 40-year extensions of the respective model spin-up simulations. In the perturbation simulations either the surface freshwater fluxes or momentum fluxes are instantaneously perturbed after the spin-up simulation to reflect the observation-derived changes in these surface fluxes and then held constant (at the perturbed level) for 40 years. They consist of sea-ice freshwater flux, glacial meltwater flux, and atmosphere-ocean momentum flux changes. Details on the model setup, forcing, and simulations can be obtained from the related research article by Haumann et al. (2020; https://doi.org/10.1029/2019AV000132).

Physical and biogeochemical oceanography data from underway measurements with an AquaLine Ferrybox during the Antarctic Circumnavigation Expedition (ACE)

Author Haumann, F. Alexander; Robinson, Charlotte; Thomas, Jenny; Hutchings, Jennifer; Pina Estany, Carles; Tarasenko, Anastasia; Gerber, Franziska; Leonard, Katherine
Publication date 31.03.2020
Persistent Identifier (PID) 10.5281/zenodo.3660852
Repository Zenodo
Abstract
This data set contains measurements from various sensors installed on the Aqualine Ferrybox system that was connected to the underway seawater supply in the Southern Ocean during the Antarctic Circumnavigation Expedition (ACE). Data was collected continuously except for periods when the pump of the underway system was switched off or the system was turned off. Data collection covers all three cruise legs in the period 24th December 2016 to 18th March 2017. Data collected with the CTG MiniPack CTD-F are temperature, salinity, pressure, and turbidity. Data collected by the Aanderaa oxygen optode include dissolved oxygen and oxygen saturation. An SBE 18 sensor measured pH. The CTG UniLux fluorometer measured chlorophyll-a concentration. All data has been quality controlled and post-cruise calibrated. Data is provided at 1-minute intervals along the cruise track. In addition, we provide satellite data (sea-surface temperature, sea-surface height, geostrophic velocity, sea-ice concentration) that was interpolated to the cruise-track and an estimate of frontal positions to supplement this underway data set where data was missing or for additional information. This circumpolar data set provides insights into the circumpolar surface ocean conditions and biogeochemistry of the Southern Ocean during one austral summer season.Note on version 1.0: The first version of this data set only contains temperature, salinity, pressure, and potential density in the post-processed file, since post-processing and quality control for turbidity, chlorophyll-a, dissolved oxygen, oxygen saturation, and pH have not been finalized. These variables will be added to the post-processed data file in a future release.

Physical and biogeochemical oceanography data from Conductivity, Temperature, Depth (CTD) rosette deployments during the Antarctic Circumnavigation Expedition (ACE)

Author Henry, Tahlia; Robinson, Charlotte; Haumann, F. Alexander; Thomas, Jenny; Hutchings, Jennifer; Schuback, Nina; Tsukernik, Maria; Leonard, Katherine
Publication date 17.09.2019
Persistent Identifier (PID) 10.5281/zenodo.3247384
Repository Zenodo
Abstract
This data set contains measurements from various sensors mounted on the Conductivity, Temperature, Depth (CTD) rosette that was deployed in the Southern Ocean during the Antarctic Circumnavigation Expedition (ACE). 63 CTD casts were carried out during three legs in the period 21st December 2016 to 16th March 2017, including one test cast and one failed cast, for which no data is available. Data include temperature, salinity, pressure, dissolved oxygen, oxygen saturation, chlorophyll-a concentration, backscatter, and photosynthetically active radiation (PAR) and reported are also the computed variables density, depth, and sound velocity. All data has been quality controlled and post-cruise calibrated, except for the oxygen data. Data is provided at 1 dbar pressure intervals for the up- and down-casts separately and as a merged bottle file when Niskin bottles were closed. This circumpolar data set provides insights into the circumpolar hydrography and biogeochemistry of the Southern Ocean during one austral summer season.

Seawater salinity sample measurements from the Antarctic Circumnavigation Expedition (ACE)

Author Haumann, F. Alexander; Leonard, Katherine; Budéus, Gereon; Meredith, Michael P.; Gorodetskaya, Irina V.; Hutchings, Jennifer; Stammerjohn, Sharon; Tsukernik, Maria; Thomas, Jenny
Publication date 19.10.2020
Persistent Identifier (PID) 10.5281/zenodo.1494924
Repository Zenodo
Abstract
This data set contains salinity measurements from discrete seawater samples that were collected in the Southern Ocean (south of 30deg S) during the Antarctic Circumnavigation Expedition (ACE). 657 samples were collected during the period December 24th, 2016 and March 18th, 2017 in the Southern Ocean from the surface ocean using the ship's underway line (UW; 328 samples) and in vertical profiles using Niskin bottles mounted on the CTD rosette (273 samples). A few additional samples (56) were collected from a parallel cast with a trace-metal rosette, with a bucket, and as duplicates to ensure data quality. All samples were analyzed for their salinity and results are reported on the Practical Salinity Scale 1978 (PSS-78; Sea-Bird Electronics, Inc., 1989). Measurements were performed on a Guildline Autosal Laboratory Salinometer 8400(B) at CSIRO (Hobart, Australia) for samples collected during leg 1, and on a OPTIMARE Precision Salinometer (OPS) at the Alfred Wegener Institute (Bremerhaven, Germany) for samples collected during legs 2 and 3. This circumpolar data set provides insights into the hydrological cycle of the Southern Ocean and the processes (precipitation, evaporation, sea-ice melting and freezing, ice-berg and land-ice melting) that determine the salinity of a certain water mass. It is being used to calibrate the CTD sensor vertical profiles (Henry et al., 2020) and thermosalinograph sensor underway measurements (Haumann et al., 2020) from the ACE cruise.

Seawater temperature profiles from Expendable Bathythermograph (XBT) probe deployments during the Antarctic Circumnavigation Expedition (ACE)

Author Haumann, F. Alexander; Thomas, Jenny; Tsukernik, Maria; Leonard, Katherine
Publication date 20.10.2020
Persistent Identifier (PID) 10.5281/zenodo.3836648
Repository Zenodo
Abstract
This data set contains vertical seawater temperature profiles measured by Expendable Bathythermograph (XBT) probes that were deployed in the Southern Ocean during the Antarctic Circumnavigation Expedition (ACE) on board the R/V Akademik Tryoshnikov. 40 XBT probes were deployed during legs 2 and 3 of the expedition in the period 25th January, 2017 to 17th March, 2017. The XBT probes are manufactured and distributed by T.S.K./Sippican Tsurumi-Seiki Co. Ltd., Yokohama, Japan (http://www.tsk-jp.com) and are of the type T-07, which is rated at a ship speed of up to 15 knots. These probes have a measuring time of 123 seconds and maximum measurement depth of about 789 m. Probes were launched from a handheld device from the stern of the ship either on the port or starboard side while the ship was moving. The deck unit recorded the temperature and the time since the probe was launched. This time was then converted to depth using the known fall rate of the probe in seawater and the coefficients provided by the manufacturer (WMO standards; Hanawa et al., 1995). The profiles were corrected for known surface biases (Kizu and Hanawa, 2002; Uehara et al., 2008). We provide the raw data, the data produced by using the coefficients provided by the manufacturer, and a corrected version in which we apply an empirical correction based on a comparison with CTD data (Henry et al., 2019), where XBT profiles were launched alongside the CTD deployment. The data has been quality controlled by comparing it to a number of CTD profiles. Data is provided at full vertical resolution and a 1-m averaged resolution. In addition, we provide derived variables such as surface mixed layer depth (temperature threshold) estimates. We are grateful to the crew of the R/V Akademik Tryoshnikov and AARI for donating these probes to our project. Their use-by date had expired, however this was not seen as an issue. This data set provides insights into the hydrography of the Southern Ocean during one austral summer season and complements the CTD temperature profiles measured during ACE by filling in the gaps between CTD stations.

Collaboration

Group / person Country
Types of collaboration
Lars H. Smedsrud, Geophysical Institute, University of Bergen Norway (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Thomas Bracegirdle, British Antarctic Survey Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Jean-Baptiste Sallée, LOCEAN-IPSL, Sorbonnes Université France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Alessandro Silvano, National Oceanography Centre Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Jennifer Hutchings, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Julia Schmale, Extreme Environments Research Laboratory, École polytechnique fédérale de Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Ivana Cerovecki, Scripps Institution of Oceanography, UC San Diego United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Nicolas Gruber, Environmental Physics, ETH Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Gereon Budéus, Alfred Wegener Institute Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Lynne Talley, Scripps Institution of Oceanography, University of California United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Stephen Riser, School of Oceanography, University of Washington United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Stephen Griffies, Geophysical Fluid Dynamics Laboratory United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Daniel Sigman, Department of Geosciences, Princetion University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
Michael Winton, Geophysical Fluid Dynamics Laboratory United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Irina Gorodetskaya, CESAM, University of Aveiro Portugal (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Seth Bushinsky, Department of Oceanography, University of Hawai`i at Manoa United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Katherine Leonard, Laboratoire des sciences cryosphériques EPFL - ENAC - IIE - CRYOS, EPFL Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Earle Wilson, Environmental Sciences and Engineering, California Institute of Technology United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Jen Thomas, Swiss Polar Institute Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Josep Pelegrí, Department of Physical and Technological Oceanography, Institute of Marine Science Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Melanie Leng, British Geological Survey Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Kenneth Johnson, Monterey Bay Aquarium Research Institute United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Jorge Sarmiento, Atmospheric and Oceanic Sciences Program, Princeton University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Michael Meredith, British Antarctic Survey Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Charlotte Robinson, Remote Sensing and Satellite Research Group, Curtin University Australia (Oceania)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Annie Wong, School of Oceanography, University of Washington United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Estrella Olmedo, Barcelona Expert Centre, Institut de Ciències del Mar, Barcelona Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Ted Maksym, Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institutio United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Rafael Catany, ARGANS Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
2020 European Polar Science Week Talk given at a conference Climatic importance of Southern Ocean salinity: Changes, challenges, and opportunities 26.10.2020 Copenhagen, Denmark Haumann Alexander;
NASA GISS Sea Level Rise Seminar Individual talk Recent changes in the southern high-latitude freshwater flux balance and their impact on Southern Ocean hydrography 07.07.2020 New York, NY, United States of America Haumann Alexander;
SOCCOM Annual Meeting Individual talk Are Southern Ocean waters supercool? 17.06.2020 Princeton, NJ, United States of America Haumann Alexander;
EGU General Assembly 2020 Poster Sea-ice Induced Southern Ocean Subsurface Warming and Surface Cooling in a Warming Climate 04.05.2020 Vienna, Austria Haumann Alexander;
Ocean Sciences Meeting 2020 Talk given at a conference Ventilation of the abyss in the Atlantic sector of the Southern Ocean 16.02.2020 San Diego, CA, United States of America Haumann Alexander;
Ocean Sciences Meeting 2020 Poster Skillful seasonal predictions of Antarctic sea ice in a dynamical forecast system 16.02.2020 San Diego, CA, United States of America Haumann Alexander;
Ocean Sciences Meeting 2020 Poster Temporal variability of Antarctic Bottom Water formation and its drivers 16.02.2020 San Diego, CA, United States of America Haumann Alexander;
Ocean Sciences Meeting 2020 Talk given at a conference A Major Shift in Southern Ocean Climate System 16.02.2020 San Diego, CA, United States of America Haumann Alexander;
Ocean Sciences Meeting 2020 Poster Evaluation of model representations of the Southern Ocean seasonal air-sea carbon dioxide flux 16.02.2020 San Diego, CA, United States of America Haumann Alexander;
AGU Fall Meeting 2019 Talk given at a conference A Major Shift in the Southern Ocean Climate System and the Role of Sea Ice 09.12.2019 San Francisco, CA, United States of America Haumann Alexander;
2nd ACE-DATA/ASAID workshop Talk given at a conference Quantifying snowfall and its contribution to surface freshening in the Southern Ocean – part 1 14.11.2019 Lausanne, Switzerland Haumann Alexander;
27th IUGG General Assembly Poster Closing the global ocean carbon loop through ventilation of Indo-Pacific Deep Water in the Southern Ocean 09.07.2019 Montréal, Canada Haumann Alexander;
27th IUGG General Assembly Talk given at a conference A major shift in the Southern Ocean climate system 09.07.2019 Montréal, Canada Haumann Alexander;
ORCHESTRA Annual Meeting 2019 Talk given at a conference Oxygen isotope constraints on the global ocean circulation and the hydrological cycle 03.07.2019 Plymouth, Great Britain and Northern Ireland Haumann Alexander;


Self-organised

Title Date Place

Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved


Associated projects

Number Title Start Funding scheme
175162 The role of Southern Ocean stratification in future ocean CO2 and heat uptake 01.10.2017 Early Postdoc.Mobility

Abstract

Throughout most of the global ocean, biological production and sinking of organic matter remove carbon and nutrients from the surface ocean [Sarmiento and Gruber, 2006]. In a natural system, this sinking flux is balanced by an upwelling of carbon and nutrients through ocean circulation and mixing [Marinov et al., 2006; Sarmiento et al., 2004]. The majority, i.e. about 80%, of the upwelling deep waters return to the surface in the Southern Ocean [e.g. Morrison et al., 2015]. This upwelling plays a vital role in the global carbon cycle and the global climate system. Sarmiento and Toggweiler [1984] were among the first to suggest that this connection between the deep and the surface ocean is the key controlling factor of natural long-term variations in the atmospheric carbon-dioxide (CO2) concentration. However, the underlying processes that alter the vertical exchange of carbon-rich waters have not been fully understood so far and, therefore, also the future response of the system to human-induced climate change remains poorly constrained. As a consequence, large uncertainties arise in future climate projections from feedbacks between climatic changes and changes in Southern Ocean vertical water mass exchange that could significantly diminish or amplify global warming.Future changes in the marginally stable vertical density gradient (here referred to as stratification) of the Southern Ocean could critically alter the vertical exchange of water masses and therefore the exchange of CO2 and heat with the atmosphere [Manabe and Stouffer, 1993; Sarmiento et al., 1998; Sigman et al., 2004]. Yet, current global climate models reveal large biases in this region [e.g. Downes et al., 2011; Sallée et al., 2013]. Consequently, it is critical to better understand the role of Southern Ocean stratification to project the magnitude of the expected future global warming accurately.In this project, we propose to investigate the effect of stratification on the future CO2 and heat uptake and release by the Southern Ocean. We will assess the related uncertainty in projected future global climate change by comparing the sensitivity of global climate model projections to changes in Southern Ocean stratification to new observational data and to a newly developed simplified model that simulates the interaction between Southern Ocean stratification and the global carbon cycle. The first part of the project (Early Postdoc.Mobility fellowship) aimed at revealing the influence of surface freshwater fluxes on Southern Ocean water masses and stratification by using the oxygen isotopic composition in water samples and analyzing profiling biogeochemical float data to determine the sensitivity of the vertical exchange to stratification changes. The here proposed continuation of this project now contrasts these new findings with global climate simulations and assesses their future response. This analysis will provide insights into the processes responsible for the large discrepancies between models. In a second step, we will develop a simplified multi-column model of the ocean to analyze the vertical exchange of water masses and their effect on changes in ocean CO2 and heat uptake and release. We will then impose freshwater flux scenarios on this simple model by perturbing the surface fluxes according to expected future changes to study the potential future response of the system and use present-day and past glacial conditions as a benchmark. This latter analysis might also reveal potential surprises in the effect of Southern Ocean stratification changes on global warming that might not be represented in current global climate models due to their biases.
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