the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
The Framework for Assessing Changes To Sea-level (FACTS) v1.0-rc: A platform for characterizing parametric and structural uncertainty in future global, relative, and extreme sea-level change
Gregory G. Garner
Tim H. J. Hermans
Shantenu Jha
Praveen Kumar
Aimée B. A. Slangen
Matteo Turilli
Tamsin L. Edwards
Jonathan M. Gregory
George Koubbe
Anders Levermann
Andre Merzky
Sophie Nowicki
Matthew D. Palmer
Chris Smith
Abstract. Future sea-level rise projections are characterized by both quantifiable uncertainty and unquantifiable, structural uncertainty. Thorough scientific assessment of sea-level rise projections requires analysis of both dimensions of uncertainty. Probabilistic sea-level rise projections evaluate the quantifiable dimension of uncertainty; comparison of alternative probabilistic methods provide an indication of structural uncertainty. Here we describe the Framework for Assessing Changes To Sea-level (FACTS), a modular platform for characterizing alternative probability distributions of global mean, regional, and extreme sea-level rise. We demonstrate its application by generating seven alternative probability distributions under multiple alternative emissions scenarios for both future global mean sea level and future relative and extreme sea level at New York City. These distributions, closely aligned with those presented in the Intergovernmental Panel on Climate Change Sixth Assessment Report, emphasize the role of the Antarctic and Greenland ice sheet as drivers of structural uncertainty in sea-level rise projections.
Robert E. Kopp et al.
Status: open (until 26 Apr 2023)
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CC1: 'Comment on egusphere-2023-14', Benjamin Grandey, 03 Feb 2023
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The authors provide a clear description and helpful discussion of a useful tool, FACTS.
I have a few minor comments and questions for the authors' consideration.
L53: The acronym FAIR is used in two senses: (i) "Findable, Accessible, Interoperable, Reusuable" (only once, at L53), and (ii) the FAIR climate model. Only the first of these is defined. To avoid potential confusion, could the acronym be reserved for the FAIR climate model?
L165: Should "FAIR 1.0" not be "FACTS 1.0"?
L250-252: When calculating thermosteric sea level rise, the authors state that the tlm/sterodynamics module uses ocean heat content (OHC) from the fair/temperature module, following Fox-Kemper et al. (2021). Does FAIR produce the OHC data, or is the climate simulation step bypassed (L150)? I understand that Fox-Kemper et al. (2021) used OHC from a two-layer energy balance model. Have I misunderstood something?
Table 1: Does every module sample a distribution? Or do some modules produce only a single time series? In particular, I am a little confused by the nature of the output from the land water storage and vertical land motion modules (L271-297).
L345: Should "Table 2" not be "Table 1"?
L375-378: I understand that Bamber et al. (2019) sought to account for dependence between the ice sheet components. Is this dependence preserved in workflow 4? Does this explain the large positive interaction evident in the early decades of workflow 4 (Fig. 4 bottom row)? If so, why does this positive interaction decrease in later decades?
Figures 2, 3, and 5 captions: Should "think" not be "thin"?
Citation: https://doi.org/10.5194/egusphere-2023-14-CC1 -
CC2: 'Clarifiation about the method to project ODSL', Dewi Le Bars, 06 Feb 2023
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Dear authors,
Thank you for this effort to clearly describe this framework and to make the code openly available. This work is of great value to the community.
I do not understand the description of the method for ODSL in l.255-258:
“The resulting global mean thermosteric sea-level rise is then combined with ocean dynamic sea-level change and the inverse barometer effect using the gridded output of CMIP6 models (see the right column of Table A1 for the models that were used in (Fox-Kemper et al., 2021)), based on the time-varying correlation structure between global mean thermal expansion and ocean dynamic sea-level change in the multi-model ensemble.”I don’t think that a correlations structure is enough information to reconstruct ODSL from global mean thermal expansion. Is this method similar to Palmer et al. 2020? (https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019EF001413) There, it is described as a linear regression but instead of being between global mean thermal expansion and ODSL it is between global mean thermal expansion and sterodynamic sea-level change:
“Following previous studies (Bilbao et al., 2015; Palmer, Howard, et al., 2018; Perrette et al., 2013), the effects of local changes in ocean density and circulation are included by establishing regression relationships between global thermal expansion and local sterodynamic sea-level change in CMIP5 climate model simulations”Your clarifications on this point would be very much appreciated. In some places the assumption of linear regression between global mean thermal expansion and ocean dynamic sea-level change is not very accurate, therefore making this assumption clearer would help people decide if this framework works for them or not.
Thank you,
Dewi Le BarsCitation: https://doi.org/10.5194/egusphere-2023-14-CC2 -
CC3: 'Comment on egusphere-2023-14', Vanessa Völz, 08 Feb 2023
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Very helpful discription of FACTS!
Chapter 3, L334: Aren't there 20,000 instead of 2,000 Monte Carlo samples?
Citation: https://doi.org/10.5194/egusphere-2023-14-CC3
Robert E. Kopp et al.
Model code and software
Framework for Assessing Changes To Sea-level Kopp, R. E., Garner, G. G., Hermans, T. H. J., Jha, S., Kumar, P., Slangen, A. B. A., Turilli, M., Edwards, T. L., Gregory, J. M., Koubbe, G., Levermann, A., Merzky, A., Nowicki, S., Palmer, M. D., & Smith, C. https://github.com/radical-collaboration/facts
Robert E. Kopp et al.
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