Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 4.790 IF 4.790
  • IF 5-year value: 5.921 IF 5-year
    5.921
  • CiteScore value: 5.27 CiteScore
    5.27
  • SNIP value: 1.551 SNIP 1.551
  • IPP value: 5.08 IPP 5.08
  • SJR value: 3.016 SJR 3.016
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 63 Scimago H
    index 63
  • h5-index value: 51 h5-index 51
Preprints
https://doi.org/10.5194/tc-2020-89
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-2020-89
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 16 Apr 2020

Submitted as: research article | 16 Apr 2020

Review status
This preprint is currently under review for the journal TC.

Large and irreversible future decline of the Greenland ice-sheet

Jonathan M. Gregory1,2,, Steven E. George1,, and Robin S. Smith1, Jonathan M. Gregory et al.
  • 1National Centre for Atmospheric Science, University of Reading, UK
  • 2Met Office Hadley Centre, Exeter, UK
  • These authors contributed equally to this work.

Abstract. We have studied the evolution of the Greenland ice-sheet under a range of constant climates typical of those projected for the end of the present century, using a dynamical ice-sheet model (Glimmer) coupled to an atmospheric general circulation model (FAMOUS-ice AGCM). The ice-sheet surface mass balance (SMB) is simulated by the AGCM, including its dependence on altitude within AGCM gridboxes. Over millennia under a warmer climate, the ice-sheet reaches a new steady state, whose mass is correlated with the initial perturbation in SMB, and hence with the magnitude of global climate change imposed. For the largest global warming considered (about +5 K), the contribution to global-mean sea-level rise (GMSLR) is initially 2.7 mm yr−1, and the ice-sheet is eventually practically eliminated (giving over 7 m of GMSLR). For all RCP8.5 climates, final GMSLR exceeds 4 m. If recent climate were maintained, GMSLR would reach 1.5–2.5 m. Contrary to expectation from earlier work, we find no evidence for a threshold warming that divides scenarios in which the ice-sheet suffers little reduction from those which it is mostly lost. This is because the dominant effect is reduction of area, not reduction of surface altitude, and the geographical variation of SMB must be taken into account. The final steady state is achieved by withdrawal from the coast in some places, and a tendency for increasing SMB due to enhancement of cloudiness and snowfall over the remaining ice-sheet, through the effects of topographic change on atmospheric circulation. If late twentieth-century climate is restored, the ice-sheet will not regrow to its present extent, owing to such effects, once its mass has fallen below a threshold of about 4 m of sea-level equivalent. In that case, about 2 m of GMSLR would become irreversible. In order to avoid this outcome, anthropogenic climate change must be reversed before the ice-sheet has declined to the threshold mass, which would be reached in about 600 years at the highest rate of mass-loss within the likely range of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.

Jonathan M. Gregory et al.

Interactive discussion

Status: open (until 11 Jun 2020)
Status: open (until 11 Jun 2020)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement

Jonathan M. Gregory et al.

Jonathan M. Gregory et al.

Viewed

Total article views: 390 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
263 125 2 390 1 1
  • HTML: 263
  • PDF: 125
  • XML: 2
  • Total: 390
  • BibTeX: 1
  • EndNote: 1
Views and downloads (calculated since 16 Apr 2020)
Cumulative views and downloads (calculated since 16 Apr 2020)

Viewed (geographical distribution)

Total article views: 173 (including HTML, PDF, and XML) Thereof 169 with geography defined and 4 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Saved

No saved metrics found.

Discussed

No discussed metrics found.
Latest update: 02 Jun 2020
Publications Copernicus
Download
Short summary
Melting of the Greenland ice-sheet as a consequence of global warming could raise global-mean sea-level by up to 7 m. We have studied this using a newly developed computer model. With recent climate maintained, sea-level would rise by 1.5–2.5 m over many millennia due to Greenland ice-loss. The warmer the climate, the greater the sea-level rise. Beyond about 3.5 m it would become partially irreversible. In order to avoid this outcome, anthropogenic climate change must be reversed soon enough.
Melting of the Greenland ice-sheet as a consequence of global warming could raise global-mean...
Citation