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Chapter 2 of the Working Group I Contribution to the IPCC Sixth Assessment Report - Input data for Figure 2.27 (v20211112)

Update Frequency: Not Planned
Latest Data Update: 2022-06-24
Status: Ongoing
Online Status: ONLINE
Publication State: Citable
Publication Date: 2023-05-15
DOI Publication Date: 2023-07-04
Download Stats: last 12 months
Dataset Size: 3 Files | 38MB


Input data for Figure 2.27 from Chapter 2 of the Working Group I (WGI) Contribution to the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6).

Figure 2.27 presents the ocean salinity trends during historical period (1950-2019) for the near surface (global map, panel a) and zonal mean sub-surface (panel b), with regions of non-significant changes masked by 'x' marks. 

How to cite this dataset
When citing this dataset, please include both the data citation below (under 'Citable as') and the following citation for the report component from which the figure originates:
Gulev, S.K., P.W. Thorne, J. Ahn, F.J. Dentener, C.M. Domingues, S. Gerland, D. Gong, D.S. Kaufman, H.C. Nnamchi, J. Quaas, J.A. Rivera, S. Sathyendranath, S.L. Smith, B. Trewin, K. von Schuckmann, and R.S. Vose, 2021: Changing State of the Climate System. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change[Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 287–422, doi:10.1017/9781009157896.004.

Figure subpanels
The figure has two panels, with data provided for all panels ( and processed via the MATLAB script (Figure_2_27.m) linked in the Related Documens section.

List of data provided
This dataset contains the global ocean salinity estimates from Durack & Wijffels (2010) based on observations from 01-01-1950 to 12-31-2019:

- Mean salinity (for the Jan/1950 to Dec/2019 period, units in PSS).
- Salinity change (for the same period, PSS/70-years).
- Salinity change error (same period, PSS/70-years).

Data provided in relation to figure
The processing of the salinity estimates from Durack & Wejffels (2010), is done in the MATLAB script (Figure_2_27.m).

Panel a:
- Ocean surface salinity change (1950-2019) and time mean (for isohalines).

Panel b:
- Zonal mean ocean subsurface salinity (0-2000m) change (1950-2019) and time mean (for isohalines).

Notes on reproducing the figure from the provided data.
The salinity change from the dataset has unit PSS/70-years. Units for salinity change and salinity change error have been converted to PSS/decade.

Salinity change error from the dataset must be multiplied by 1.09 (to account for the resolved error when a bootstrap resampling was undertaken) x 1.64485 (i.e., z-value for 90% confidence interval) in order to get the uncertainty for the stippling.

The stippling in both panels is done for regions (either surface salinity, panel a, or zonal mean salinity, panel b) where the salinity uncertainties are larger than the salinity trend.

Sources of additional information
The following weblinks are provided in the Related Documents section of this catalogue record:
- Link to the IPCC AR6 website
- Link to the report component containing the figure (Chapter 2)
- Link to the Supplementary Material for Chapter 2, which contains details on the input data used in Table 2.SM.1
- Link to the code for the figure, archived on Zenodo.

Citable as:  Durack, P.J. (2023): Chapter 2 of the Working Group I Contribution to the IPCC Sixth Assessment Report - Input data for Figure 2.27 (v20211112). NERC EDS Centre for Environmental Data Analysis, 04 July 2023. doi:10.5285/78ad6999f2d743d2a7db16757c27b549.
Abbreviation: Not defined
Keywords: IPCC-DDC, IPCC, AR6, WG1, WGI, Sixth Assessment Report, Working Group I, Physical Science Basis, Chapter 2, Changing state, Multi-millennial context, pre-industrial, Natural forcing, anthropogenic forcing, Radiative forcing, Large-scale indicators, observed changes, Modes of variability, Figure 2.27 Input, ocean salinity


Previous Info:
No news update for this record
Previously used record identifiers:
No related previous identifiers.
Access rules:
Public data: access to these data is available to both registered and non-registered users.
Use of these data is covered by the following licence: When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record.
Data lineage:

Data produced by Intergovernmental Panel on Climate Change (IPCC) authors and supplied for archiving at the Centre for Environmental Data Analysis (CEDA) by the Technical Support Unit (TSU) for IPCC Working Group I (WGI).
Data curated on behalf of the IPCC Data Distribution Centre (IPCC-DDC).

Data Quality:
Data as provided by the IPCC
File Format:
txt, netCDF

Process overview

This dataset was generated by the computation detailed below.

Caption for Figure 2.27 from Chapter 2 of the Working Group I (WGI) Contribution to the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6)


Changes in ocean salinity. Estimates of salinity trends using a total least absolute differences fitting method for (a) global near-surface salinity (SSS) changes and (b) global zonal mean subsurface salinity changes. Black contours show the associated climatological mean salinity (either near-surface (a) or subsurface (b)) for the analysis period (1950–2019). Both panels represent changes of Practical Salinity Scale 1978 [PSS-78], per decade. In both panels green denotes freshening regions and orange/brown denotes regions with enhanced salinities (‘x’ marks denote non-significant changes). Further details on data sources and processing are available in the chapter data table (Table 2.SM.1).

Input Description


Output Description


Software Reference


  • long_name: Potential Temperature change 19500101-20191231
  • standard_name: change_over_time_in_sea_water_potential_temperature
  • var_id: thetao_change
  • long_name: Potential Temperature change error 19500101-20191231
  • var_id: thetao_change_error
  • standard_name: sea_water_potential_temperature
  • units: degree_C
  • long_name: Potential Temperature mean 19500101-20191231
  • var_id: thetao_mean
  • long_name: Salinity change 19500101-20191231
  • standard_name: change_over_time_in_sea_water_salinity
  • var_id: salinity_change
  • long_name: Salinity change error 19500101-20191231
  • var_id: salinity_change_error
  • standard_name: sea_water_salinity
  • units: 1e-3
  • long_name: Salinity mean 19500101-20191231
  • var_id: salinity_mean
  • var_id: depth_bnds
  • var_id: latitude_bnds
  • var_id: longitude_bnds
  • var_id: depth
  • long_name: sea_water_pressure
  • standard_name: sea_water_pressure
  • units: decibar
  • var_id: time_climatology

Co-ordinate Variables

  • units: degrees_north
  • standard_name: latitude
  • var_id: latitude
  • long_name: latitude
  • units: degrees_east
  • standard_name: longitude
  • var_id: longitude
  • long_name: longitude
  • long_name: time
  • standard_name: time
  • var_id: time
  • units: days
Temporal Range
Start time:
End time:
Geographic Extent

Related parties
Authors (1)