Sea Level Budget Closure

This project aims to reduce current uncertainties of sea level change and its individual components, resulting in better closure of the sea level budget.

About

The sea level budget closure project

Sea level is one of the most prominent indicators of climate change. It integrates changes of several components of the climate system in response to anthropogenic forcing as well as natural forcing factors related to natural sources and internal climate variability.

Present-day global mean sea level rise primarily reflects ocean warming (through thermal expansion of sea waters) and land ice melt. Changes in land storage constitute an additional contribution. As a primary objective of the ESA CCI programme was to reduce current uncertainties of sea level change and its individual components, better closure of the sea level budget should now be possible. This will improve our understanding of processes involved in causing global mean sea level rise and its regional variability, and further help to improve models used for projections of future climate changes.

Closure of the sea level budget implies that we have:
ΔSL(t) = ΔM_Ocean(t) + ΔSSL(t)
where ΔSL(t) is time-variable sea level, ΔM_Ocean(t) is time variable ocean mass component, ΔSSL(t) is steric sea level components (effect of the depth integrated change in sea water density due to ocean temperature and salinity variations).

Water mass conservation in the climate system implies closure of the ocean mass budget:
ΔM_Ocean (t) = [ ΔM_Glaciers(t) + ΔM_{ice sheets}(t) + ΔM_LWS(t) + ΔM_Atm(t) + missing mass terms ]
where the ΔM(t) terms in the right hand side refer to glaciers and ice sheets mass balances, changes in land water storage (LWS, including seasonal snow cover), and atmospheric water vapour.

Studying the sea level budget and the ocean mass budget with accurate climate records will bring major scientific benefits – adding confidence to satellite-based assessments of climate change, shedding light on missing or poorly known processes such as land hydrology that remain a challenge for Earth Observation, or heat uptake by the deep ocean. This will allow the key processes affecting sea level rise to be precisely quantified, leading to more informed model projections. Together with extreme events like storm surges and tropical cyclones, regional/local sea level changes represent a major threat in low-lying, highly populated coastal regions of the world, each of which affects coastal planning. The project is therefore a timely opportunity to add societal value and visibility to the CCI, allowing it to form the backbone of a milestone contribution to climate science.

This project intends to analyse in an integrative context recent results obtained by the ESA CCI programme for the sea level, glaciers and ice sheets Essential Climate Variables (ECV), with additional account for assessments of the ocean thermal expansion component which utilise the CCI Sea Surface Temperature ECV. Among other objectives, an important task will consist of assessing the quality of the CCI products involved in the sea level budget.

The first phase of this project covered the precise altimetry era (starting in 1993) with a special focus given to the period 2003/2005 to 2015, coinciding with the availability of GRACE space gravimetry data and Argo drifter data.

The new project phase (SBLC_cci+) aims to improve the closure of the global mean sea level budget by: 1) lengthening the time series, 2) assessing budget closure at global and regional scales, 3) providing an explanation of temporal and spatial variability at global and local scales. Depending on the availability of the various elements, the global sea level budget will be updated up to 2022/2023. In addition, the project will address the regional variability of sea level and sea surface temperature, and investigate the contributions of natural/internal climate variability and anthropogenic forcing (detection/attribution) to the associated spatial trends. By extending to regional spatial scales, we can pinpoint areas where the sea level budget does not close, resulting in a regional breakdown of the assessment of the items that accounts for a significant portion of the individual components used.

Data

Phase II data availability

Document	Access
No phase II data are currently available

Phase I

Document	Access
Compiled dataset of time series (at monthly sampling) of all elements of the global mean sea-level budget and ocean-mass budget	http://dx.doi.org/10.5285/17c2ce31784048de93996275ee976fff
D2.1.1 – Data package containing initial time series of individual components (version 0) 01.06.2017
D2.2 – Data package containing sample time series of preliminary improved individual components 15.12.2017
D2.3.1 – Data package containing preliminary improved time series of individual components (version 1) 31.08.2018
D2.4.1 – Data package containing final improved time series of individual components (version 2) 14.02.2019

Key Documents

There are a range of technical reports and product descriptions available from the Sea Level Budget Closure project.

Phase II

Technical Reports

D1.1 Science Requirement Document (version 1.3). Accepted 22.07.2024
D2.1 Product Specification Document (version 1). Accepted 22.07.2024
D2.2 Data Access Requirement Document (version 1). Accepted 22.07.2024

Phase I

Team

Phase II (2023-2026)

The Sea Level Budget Closure project team is composed of the following partners:

CCI Sea level budget Closure team (phase II)

European Space Agency
European Centre for Space Applications and Telecommunications (ECSAT)
Dr. Sarah Connors
Harwell, UK
Contribution: Monitoring of this project
Magellium
- Dr. Anny Cazenave
  Toulouse, France
  Contribution: validation team and deputy science leader
- Michael Ablain
  Toulouse, France
  Contribution: project manager
- Dr. Anne Barnoud
  Toulouse, France
  Contribution: scientific engineer in validation team
- Dr. Marie Bouih
  Toulouse, France
  Contribution: scientific engineer in EO science and system developers teams
- Robin Fraudeau
  Toulouse, France
  Contribution: deputy project manager and scientific engineer in EO science and system developers teams
Technische Universität Dresden
- Prof. Martin Horwath
  Dresden, Germany
  Contribution: EO science and system developers teams leader
- Phd. Thorben Döhne
  Dresden, Germany
  Contribution: researcher in EO science and system developers teams
Laboratoire d’Etudes en Géophysique et Océanographie Spatiales (LEGOS)
- Dr. Benoît Meyssignac
  Toulouse, France
  Contribution: science leader
- Dr. Alejandro Blazquez
  Toulouse, France
  Contribution: researcher in EO science and system developers teams
DATLAS
Dr. Stephanie Leroux
Grenoble, France
Contribution: scientific engineer in EO science and system developers teams
CNR-ISMAR
- Dr. Andrea Storto
  Ancona, Italy
  Contribution: researcher in validation team
- Dr. Chunxue Yang
  Ancona, Italy
  Contribution: researcher in validation team
UBO-LOPS
- Dr. Nicolas Kolodziejczyk
  Brest, France
  Contribution: researcher in EO science and system developers teams
- Dr. William Llovel
  Brest, France
  Contribution: researcher in EO science and system developers teams
University of Bristol
Prof. Jonathan Bamber
Bristol, UK
Contribution: researcher in validation team
UNIBO
Prof. Girogio Spada
Bologna, Italy
Contribution: Antarctic and Greenland Ice Sheets
Nansen Environmental and Remote Sensing Center (NERSC)
- Dr. Antonio Bonaduce
  Bergen, Norway
  Contribution: researcher in validation team
- Dr. Roshin P. Raj
  Bergen, Norway
  Contribution: researcher in validation team
- Prof. Johnny A. Johannessen
  Bergen, Norway
  Contribution: researcher in validation team

Phase I (2018-2020)

The Sea Level Budget Closure project team during phase I (2018-2020) was composed of the following partners.

European Space Agency
European Space Research Institute (ESRIN)
Dr. Jérôme Benveniste
Frascati, Italy
Contribution: launch and monitoring of this project
SERCO for ESA
c/o European Space Research Institute (ESRIN)
Dr. Marco Restano
Frascati, Italy
Contribution: review deliverables of this project and provide technical support
Technische Universität Dresden
Prof. Martin Horwath
Dresden, Germany
Contribution: Scientific leader and project manager Ocean mass contribution / Ocean mass budget assessment
Laboratoire d’Etudes en Géophysique et Océanographie Spatiales (LEGOS)
Dr. Anny Cazenave
Toulouse, France
Contribution: Global mean sea level change / Sea level budget assessment
University of Reading
Prof. Christopher Merchant
Reading, UK
Contribution: Steric sea level change (contributions to this project from SSL4SLBC)
University of Bremen
Prof. Ben Marzeion
Bremen, Germany
Contribution of Global Glacier
University of Zurich
Dr. Frank Paul
Zurich, Switzerland
Contribution of Global Glacier
University of Leeds
Prof. Andrew Shepherd
Centre for Polar Observation and Modelling (CPOM), School of Earth and Environment Leeds,
UKContribution of Antarctic and Greenland Ice Sheets
Technical University of Denmark / DTU Space
Prof. Rene Forsberg
Kopenhagen, Denmark
Contribution of Antarctic and Greenland Ice Sheets
Goethe-Universität Frankfurt
Prof. Petra Döll
Frankfurt/M., Germany
Contribution: Continental Hydrology
Nansen Environmental and Remote Sensing Center (NERSC)
Prof. Johnny A. Johannessen
Bergen, Norway
Contribution:Arctic Ocean
Technical University of Denmark / DTU Space
Dr. Ole B. Andersen
Kopenhagen, Denmark
Contribution: Arctic Ocean

Publications

Click on the following links for publications relating to the Sea Level Budget Closure project.

Phase II:

Llovel, W., Balem, K., Tajouri, S. and Hochet, A. (2023): Cause of substential global mean sea level rise over 2014-2016. Geophysical Research Letters, 50, e2023GL104709,doi: 10.1029/2023GL104709
Meyssignac, B., Ablain, M., Guérou, A., Prandi, P., Barnoud, A., Blazquez, A., Fourest, S., Rousseau, V., Bonnefond, P., Cazenave, A., Chenal, J., Dibarboure, G., Donlon, C., Benveniste, J., Sylvestre-Baron, A. and Vinogradova, N. (2023): How accurate is accurate enough for measuring sea-level rise and variability. Nature Climate Change, 13, 796–803, doi: 10.1038/s41558-023-01735-z

Phase I:

Horwath, M., Gutknecht, B. D., Cazenave, A., Palanisamy, H. K., Marti, F., Marzeion, B., Paul, F., Le Bris, R., Hogg, A. E., Otosaka, I., Shepherd, A., Döll, P., Cáceres, D., Müller Schmied, H., Johannessen, J. A., Nilsen, J. E. Ø., Raj, R. P., Forsberg, R., Sandberg Sørensen, L., Barletta, V. R., Simonsen, S. B., Knudsen, P., Andersen, O. B., Ranndal, H., Rose, S. K., Merchant, C. J., Macintosh, C. R., von Schuckmann, K., Novotny, K., Groh, A., Restano, M., and Benveniste, J. (2022): Global sea-level budget and ocean-mass budget, with a focus on advanced data products and uncertainty characterisation, Earth Syst. Sci. Data, 14, 411–447, https://doi.org/10.5194/essd-14-411-2022.
Groh, A., M. Horwath (2021): Antarctic Ice Mass Change Products from GRACE/GRACE-FO Using Tailored Sensitivity Kernels. Remote Sensing, 13, 1736, doi: 10.3390/rs13091736
Malles, J.-H. and Marzeion, B. (2021): Twentieth century global glacier mass change: an ensemble-based model reconstruction, The Cryosphere, 15, 3135–3157, https://doi.org/10.5194/tc-15-3135-2021.
Simonsen, S. B., Barletta, V. R., Colgan, W. T., & Sørensen, L. S. (2021). Greenland Ice Sheet mass balance (1992–2020) from calibrated radar altimetry. Geophysical Research Letters, 48, e2020GL091216. https://doi.org/10.1029/2020GL091216
Vishwakarma, B. D., Horwath, M., Groh, A., & Bamber, J. L. (2021). Accounting for GIA signal in GRACE products. Geophysical Journal International, doi: 10.1093/gji/ggab464
Cáceres, D., Marzeion, B., Malles, J. H., Gutknecht, B., Müller Schmied, H., and Döll, P. (2020): Assessing global water mass transfers from continents to oceans over the period 1948–2016, Hydrol. Earth Syst. Sci., https://doi.org/10.5194/hess-24-4831-2020
Ludwigsen, C. A., & Andersen, O. B. (2020). Contributions to Arctic Sea Level from 2003-2015. Advances in Space Research. doi: 10.1016/j.asr.2019.12.027
Popp, T., Hegglin, M. I., Hollmann, R., Ardhuin, F., Bartsch, A., Bastos, A., Bennett, V., Boutin, J., Brockmann, C., Buchwitz, M., Chuvieco, E., Ciais, P., Dorigo, W., Ghent, D., Jones, R., Lavergne, T., Merchante, C. J., Meyssignac, B., Paul, F., Quegan, S., Sathyendranath, S., Scanlon, T., Schröder, M., Simis, S. G. H., & Willén, U. (2020). Consistency of satellite climate data records for Earth system monitoring. Bulletin of the American Meteorological Society, 101(11), E1948-E1971, https://doi.org/10.1175/BAMS-D-19-0127.1
Raj, R.P., Andersen, O.B., Johannessen, J.A., Gutknecht, B.D., Chatterjee, S., Rose, S.K., Bonaduce, A., Horwath, M., Ranndal, H., Richter, K., Palanisamy, H., Ludwigsen, C.A., Bertino, L., Ø. Nilsen, J.E., Knudsen, P., Hogg, A., Cazenave, A., Benveniste, J. (2020): Arctic Sea Level Budget Assessment during the GRACE/Argo Time Period. Remote Sens. 2020, 12, 2837. doi:10.3390/rs12172837
Ablain, M., Meyssignac, B., Zawadzki, L., Jugier, R., Ribes, A., Spada, G., Benveniste, J., Cazenave, A., and Picot, N. (2019): Uncertainty in satellite estimates of global mean sea-level changes, trend and acceleration. Earth Syst. Sci. Data, 11, 1189–1202, doi: 10.5194/essd-11-1189-2019.
Cazenave, A., Hamlington, B., Horwath, M., Barletta, V., Benveniste, J., Chambers, D., Döll, P., Hogg, A.E., Legeais, J.F., Merrifield, M., Meyssignac, B., Mitchum, G., Nerem, S., Pail, R., Palanisamy, H., Paul, F., von Schuckmann, K., Thompson, P. (2019): Observational Requirements for Long-Term Monitoring of the Global Mean Sea Level and Its Components Over the Altimetry Era. Frontiers in Marine Science, 6, 582. doi: 10.3389/fmars.2019.00582
Mottram, R., Simonsen, S.B., Høyer Svendsen, S., Barletta, V.R., Sandberg Sørensen, L., Nagler, T., Wuite, J., Groh, A., Horwath, M., Rosier, J., Solgaard, A., Hvidberg, C.S., Forsberg, R. (2019): An Integrated View of Greenland Ice Sheet Mass Changes Based on Models and Satellite Observations. Remote Sensing, 11(12), 1407, doi: 10.3390/rs11121407
Rose, S.K., Andersen, O.B., Passaro, M., Ludwigsen, C.A., Schwatke, C. (2019): Arctic Ocean Sea Level Record from the Complete Radar Altimetry Era: 1991–2018. Remote Sensing, 11(14), 1672, doi: 10.3390/rs11141672
Shepherd, A., Gilbert, L., Muir, A.S., Konrad, H., McMillan, M., Slater, T., Briggs, K.H., Sundal, A.V., Hogg, A.E., Engdahl, M. (2019): Trends in Antarctic Ice Sheet Elevation and Mass. Geophysical Research Letters, 46, 8174–8183, doi: 10.1029/2019GL082182
Zemp, M., Huss, M., Thibert, E., Eckert, N., McNabb, R., Huber, J., Barandun, M., Machguth, H., Nussbaumer, S.U., Gärtner-Roer, I., Thomson, L., Paul, F., Maussion, F., Kutuzov, S., Cogley, J.G. (2019): Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016. Nature 568, 382–386, doi: 10.1038/s41586-019-1071-
Martinec, Z., Klemann, V., van der Wal, W., Riva, R.E.M., Spada, G., Sun, Y., Melini, D., Kachuck, S.B., Barletta, V., Simon, K., A, G., James, T.S. (2018): A benchmark study of numerical implementations of the sea level equation in GIA modelling. Geophysical Journal International, 215, 389-414, doi: 10.1093/gji/ggy280

Contacts

For any questions concerning the project, please contact Michael Ablain, Benoît Meyssignac or Jérôme Benveniste who launched and monitors the project.

Technical leader:
Michael Ablain
Magellium
Earth Observation Unit
31000 Toulouse
France
Email: michael.ablain@magellium.fr

Scientific leader:
Dr. Benoît Meyssignac
CNRS-LEGOS/CNES
31000 Toulouse
France
Email: benoit.meyssignac@univ-tlse3.fr

Technical Officer:
Dr. Sarah Connors
European Space Agency
European Centre for Space Applications and Telecommunications (ECSAT)
Email: sarah.connors@esa.int