Data for Figure 9.13 from Chapter 9 of the Working Group I (WGI) Contribution to the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6).

Figure 9.13 shows Arctic sea ice historical records and CMIP6 projections.

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How to cite this dataset
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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:
Fox-Kemper, B., H.T. Hewitt, C. Xiao, G. Aðalgeirsdóttir, S.S. Drijfhout, T.L. Edwards, N.R. Golledge, M. Hemer, R.E. Kopp, G. Krinner, A. Mix, D. Notz, S. Nowicki, I.S. Nurhati, L. Ruiz, J.-B. Sallée, A.B.A. Slangen, and Y. Yu, 2021: Ocean, Cryosphere and Sea Level Change. 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. 1211–1362, doi:10.1017/9781009157896.011.

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Figure subpanels
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The figure has 2 subpanels, with data provided for both panels.

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List of data provided
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This dataset contains:
- (Left panel) Absolute anomaly of monthly-mean Arctic sea ice area during the period 1979 to 2019 relative to the average monthly-mean Arctic sea ice area during the period 1979 to 2008.
- (Right panel) Sea ice concentration in the Arctic for March and September, which usually are the months of maximum and minimum sea ice area, respectively.

First column: Satellite-retrieved mean sea ice concentration during the decade 1979–1988. Second column: Satellite-retrieved mean sea ice concentration during the decade 2010-2019.
Third column: Absolute change in sea ice concentration between these two decades, with grid lines indicating non-significant differences.
Fourth column: Number of available CMIP6 models that simulate a mean sea ice concentration above 15 % for the decade 2045–2054.

The average observational record of sea ice area is derived from the UHH sea ice area product (Doerr et al., 2021), based on the average sea ice concentration of OSISAF/CCI (OSI-450 for 1979–2015, OSI-430b for 2016–2019) (Lavergne et al., 2019), NASA Team (version 1, 1979–2019) (Cavalieri et al., 1996) and Bootstrap (version 3, 1979–2019) (Comiso, 2017) that is also used for the figure panels showing observed sea ice concentration.

Further details on data sources and processing are available in the chapter data table (Table 9.SM.9)

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Data provided in relation to figure
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Data provided in relation to Figure 9.13

- Data file: NSIDC_polehole_big.nc
- Data file: NSIDC_polehole_small.nc
- Data file: SeaIceArea__NorthernHemisphere__monthly__UHH__v2019_fv0.01.nc
- Data file: SeaIceArea__SouthernHemisphere__monthly__UHH__v2019_fv0.01.nc
- Data file: cryo_div.txt
- Data file: cryo_seq.txt

Datafile 'mapplot_data.npz' included in the 'Plotted Data' folder of the dedicated GitHub repository is not archived here but on Zenodo at the link provided in the Related Documents section of this catalogue record.

CMIP6 is the sixth phase of the Coupled Model Intercomparison Project.
NSIDC is the National Snow and Ice Data Center.
UHH is the University of Hamburg (Universtität Hamburg).

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Notes on reproducing the figure from the provided data
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Both panels were plotted using standard matplotlib software - code is available via the link in the documentation.

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Sources of additional information
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The following weblinks are provided in the Related Documents section of this catalogue record:
- Link to the figure on the IPCC AR6 website
- Link to the report component containing the figure (Chapter 9)
- Link to the Supplementary Material for Chapter 9, which contains details on the input data used in Table 9.SM.9
- Link to the data and code used to produce this figure and others in Chapter 9, archived on Zenodo.
- Link to the output data and scripts for this figure, contained in a dedicated GitHub repository.