the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 11 Nov 2025
21st century change in precipitation on the Greenland Ice Sheet using high resolution regional climate models
Abstract. An ensemble of regional climate model simulations downscaling global climate models within Coupled Model Intercomparison Project Phase 6 (CMIP6) is used to estimate future precipitation changes for the Greenland ice sheet under a range of climate change pathways. The regional climate models are HIRHAM5, MAR3.12 and RACMO2.3p2 contributing a total of eleven simulations for the SSP5-8.5 scenario, five simulations for the SSP2-4.5 scenario and four simulations for the SSP1-2.6 scenario. The Greenland ice sheet is divided into six drainage basins to evaluate the change in total (snow plus rain) precipitation in regions with different precipitation characteristics. Compared with the reference period 1971–2000, the ensemble median change in precipitation for the full Greenland ice sheet for the SSP5-8.5 scenario is estimated to be about +60 Gt (+8 %) per year during the 2031–2060 period and +170 Gt (+24 %) per year during the 2071–2100 period. We see similar ensemble median change for the 2031–2060 period for the SSP1-2.6 and SSP2-4.5 scenarios while the 2071–2100 change is +40 and +80 Gt (+6 and +11 %) per year for SSP1-2.6 and SSP2-4.5, respectively. In contrast to this, recent studies show that runoff is projected to increase by a much larger amount (around 2,000 Gt per year for the end of this century). Using linear regression on the annual mean change in near-surface (2 m) air temperature and precipitation over the ice sheet, we estimate an increase of about 35 Gt per year in precipitation (equal to about 5 %) for every degree of warming during the 21st century. We also study the change in phase of the total precipitation, showing a relative increase in rainfall, particularly along the outer edge and the southern part of the ice sheet. The regional climate model output is compared with an ensemble of global climate models within CMIP6 showing similar patterns in precipitation change but with overall larger changes in the CMIP6 ensemble median compared with the regional climate model ensemble median.
Competing interests: At least one of the (co-)authors is a member of the editorial board of The Cryosphere.
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2025-4360', Jason Box, 01 Dec 2025
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RC2: 'Comment on egusphere-2025-4360', Anonymous Referee #2, 17 Feb 2026
Review of manuscript “21st century change in precipitation on the Greenland Ice Sheet using high resolution regional climate models” by Boberg et al.
General overview of the manuscript
The manuscript looks at changes in solid and liquid precipitation over the Greenland ice sheet (GrIS) in an ensemble of high resolution future projections compared with those obtained with 34 CMIP6 global climate model in three different SSP scenarios (SSP1-2.6/SSP2-4.5/SSP5-8.5) and observations/reanalysis datasets. High resolution ensemble members are obtained in three different ways: (i) with the regional climate model (RCM) HIRHAM, forced with EC-Earth3; (ii) with a set of # CMIP6 models downscaled with MAR and (iii) with the RCM RAMCO forced by CESM2-L. Total precipitation over GrIS is projected to increase up to 24% in the 2071-2100 period for the most extreme SSP scenario. The model spread and changes in precipitation characteristics (e.g. total precipitation versus snowfall/rainfall fraction) are analysed over the entire GrIS and over six different catchments. Overall, all models tend to underestimate the total amount of precipitation over the most part of GrIS during the validation period, with the exception of coastal areas. In general, I find that the manuscript is well written, although a few points need further clarification to ensure that the paper can be accessible to a broader spectrum in the scientific community. The research topic is relevant to the broad scientific community and the manuscript represents a good fit for Copernicus journal “The Cryosphere”. Most comments mainly aim to improve the readability and accessibility of the paper, and to better describe Figures. I would recommend publication in TC after current concerns have been successfully addressed.
Major comments
- Line(s) 95, table 1. The table caption reads “Numbers in blue/green/red are for the SSP1-2.6/SSP2-4.5/SSP5-8.5 scenario”, however all tables are in black and white in the pdf. Also I am not sure why some values are set to N/A, does it mean that for that model the scenario is not available? Please clarify. Moreover, at first glance it seems like the bias between the ensemble and CARRA over the 1971-2000 period is -142 Gt, and that for the 1991-2022 period the bias is -307 Gt. Again, it takes a while to understand that the last two columns represent the bias between the 7 chosen observation stations and the models (CARRA). Why is a small set of 7 weather station used to calculate the bias when the most of the anaylsis afterwards shows the comparison with CARRA? I would suggest to show in the table the bias with CARRA instead, or show both and remove the RMSE. Also that the CARRA value in the second column to the left is for a different period: this is misleading and I would at least mark the value with an asterisk, although I would suggest to re-think the table.
- Line(s) 129-130. Figure 2 is described in too little detail. First, it is difficult in the figure to distinguish different colours from the colour scale: I suggest adding isolines on the plot and highlight one level every two or three, e.g. 15%, 45%, 75%. This way it would be easier to notice differences among different plots. Second, 12 different maps are described in two short sentences, with only a very general statement on where “positive” or “negative” biases are found, entirely leaving to the reader the task of trying to catch and interpret the values on the maps. Please revise the figure description adding values to the description of panels (b)-(l). See below a suggestion on how to improve the paragraph:
“We see similar patterns for all models with large areas with a negative bias of about -15-30% in the central parts of the GrIS and smaller areas with a positive bias up to +40-50% along the Greenland coastline. The model with the highest bias are (add models), which show a deviation from the climatology up to -50%. Four of the MAR models (Figure 2f to 2i) show a large positive bias from the climatology, with values of about +40-50% in region NW and NO, which correspond to an increase in precipitation of about (add number) mm”. Note that the numbers provided above may be incorrect but this is currently what I can gather from the figure. - Line(s) 143-149. Figure 3. Same comment as for Figure 2. Please add values to the text and explain their meaning in the context of your analysis.
- Line(s) 163-167. Figure 4. Same comment as for Figure 2. Please add values to the text and explain their meaning in the context of your analysis. I would also recommend shifting the panels from a 6 by 3 grid to a 3 by 6 to better suit the page format.
- Line(s) 187-194. Figure 5. Same comment as for Figure 2. Please add values to the text and explain their meaning in the context of your analysis. I would also suggest to add in each plot the period/SSP scenario as done in Fig. 4.
- Line(s) 196-203. Figure 6. Here I would say the colour shading is clear enough and values of the snowfall/precipitation fraction are reported in the text. However, I would explicitly include at the beginning of the paragraph the definition of the snowfall fraction (snowfall/total precipitation) and include an example to show what a certain value means.
- Line(s) 222-227. Figure 7. It took me a while to understand why the total precipitation doesn’t seem to match the basin values. Please write explicitly in the text that this is the sum of the other values and the y-axis of reference is the right one. Also see previous comment for Figure 2. Please add values to the text and explain their meaning in the context of your analysis.
- Line(s) 244-297. In general, the discussion is missing a paragraph outlining the limitations of this study and of the used datasets.
- Line(s) 264-267. The importance of the discrepancy between the runoff and the increase in precipitation is prominently present in the abstract, however only two brief sentences on the topic are present in the discussion with no explanation on what could cause the increase in runoff. Runoff ultimately contributes to sea level rise and is therefore a key element of Greenland research. While I understand that the scope of this study is to analyse precipitation changes, it is important to elaborate a bit more the implications of these findings for GrIS runoff in the discussion, and explore potential reasons why this discrepancy is present in the first place. My uninformed assumption would be that surface temperature increase and surface melting may play a big role into explaining the runoff, but I suppose other explanations like model parametrisation or fixed ice sheet characteristics may play a role as well.
Minor comments
- Line(s) 110-111. Could you please add one sentence to clarify what “undercatch corrected” means. This seems a quite specific/technical term that many readers may not be familiar with.
- Line(s) 249-254. Figure 9. I would suggest to move the description of this figure to the results section and focus on the interpretation/comparison with other literature in the discussion.
- Line(s) 269-271. What about Greenland blocking? Please see
Davini, P.,Weisheimer, A., Balmaseda, M., Johnson, S. J., Molteni, F., Roberts, C. D., Senan, R., and Stockdale, T. N.: The representation of winter Northern Hemisphere atmospheric blocking in ECMWF seasonal prediction systems, Q. J. Roy. Meteor. Soc., 147, 1344–1363, https://doi.org/10.1002/qj.3974, 2021.
Citation: https://doi.org/10.5194/egusphere-2025-4360-RC2
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- 1
Summary
The submitted article is clearly written and adresses an important topic, adding largely missing detailed insight on how much should Greenland precipitation change in a warming future. Besides suggesting several missing relevant citations and questioning the likely important future model treatment of sea ice decline in Greenland precipitation change, I take issue mainly with the magnitude of the precipitation sensitivity to temperature, arguing that the conclusion of ~5%/K, being considerably lower than theory (~7%/K) appears to me more due to the research design than reality given there exist research finding 7%/K using observation-based approach.
I am a fan of the work that deserves to be published, especially on working with my comments. Upon successful adressing of my comments, I think the work will deserve nomination for a highlight by the EGU (is a question reviewers are asked in this review form).
**high level critique** in no particular order of importance...
Precipitation feedbacks with changing sea ice appear to be a key consideration, deserving perhaps a whole new section in this study. The following is relevant to incorporate in discussion: Stroeve, J. C., Mioduszewski, J. R., Rennermalm, A., Boisvert, L. N., Tedesco, M., and Robinson, D.: Investigating the localscale influence of sea ice on Greenland surface melt, The Cryosphere, 11, 2363–2381, https://doi.org/10.5194/tc-11-2363-2017, 2017.
230 "7% increase per degree warming", the idea of warmer atmosphere, more water vapor appears as a statistically robust feature of observational data, specifically N Atlantic SST and Northern Hemisphere near-surface air temperatures correlation with Greenland snow accumulation, matching theory articulated by Treberth (doi: 10.3354/cr00953), see https://doi.org/10.1175/JCLI-D-12-00373.1 figure 9a, Table 3 and related discussion. The J. Clim. article finds the expected 7%/K sensitivity using observations, in the following Figure 9 comment, I suggest ways to possibly find a more credible result after all the J. Clim. article has more observation constraint. As is, the conclusion of "4.9%, 5.1% and 4.5% increase in precipitation per Kelvin for HIRHAM, MAR and RACMO," I fear may be misleading...
Figure 9: Ensemble median... is there a GCM that is arguably more reliable? Groupling ALL models may obscure a more realistic result. I'm wondering which models given 7%/K and if those are of a model class that is arguably more reliable? If so, a new figure could feature that more credible model result. at line 206 you get into the issue "dependency on the choice of GCM."
...Well ok at line 285 "Bochow 285 et al. (2024) used 32 GCMs within the CMIP6 project and found a mean value of 6% K-1", but I just hope you can build an even more convincing argument why or why not the actually should be drier than theory! If it's something about dynamics, then I think you need to do more sensitivity analysis, i.e. burden of proof on this study.
...286-299 "A 5% increase in precipitation per degree warming over the GrIS were found by Gregory and Huybrechts (2006) and by Fettweis et al. (2013)." Do they provide a credible explanation why the sensitivity is lower than 'observed' by https://doi.org/10.1175/JCLI-D-12-00373.1 ?
Whatever extent IPCC AR6 examines future Greenland precipitation change warrants treatment here.
Figure 8: Annual sum of precipitation nonlinearity for rain is striking, deserves highlight in abstract and conclusions and has important implications you get into lines 256-261 that can be further elaborated, more citations, more to the point text... some thoughts, partly redundant...driving snow metamorphic (albedo decline) feedbacks and pontential firn heating at depth (ONLY IF HEAVY RAIN AND LOW TEMPERATURE SNOW https://doi.org/10.1029/2023GL103654), if rain is light, it does not infiltrate and instead the heat radiates away https://doi.org/10.1029/2021GL097356
line 260 "rainfall events lower the surface albedo", https://doi.org/10.1029/2021GL097356 cites relevant detail. Another is Colbeck, S.: Theory of metamorphism of wet snow, 1973.
at the first mention of runoff, I was thinking, why? I mean this is a precipitation change study. Then at line 264 "Glaude et al. (2024) however, show from some of the same simulations as we analyse here, that the melt and runoff is projected to increase by a much larger"... again, runoff is beside the point. I recommend you keep the study focused on precip change and not do other mass balance terms and so avoid needing to add yet more (irrelevant) citations.
PLEASE use "ice sheet" instead of "GrIS" once it's obvious the geographic focus is Greenland. having read though, there are really few places where an abbreviation would be needed. Therefore, clearly it's not.
** lower level critique **
KEY: "io" means "instead of", NUMEBRS: line numbers
32 "projected increase in snowfall, compensating for increased runoff", consider also https://doi.org/10.1029/2024GL110121
40 "higher temperature of rain compared to melt water", surprisingly insignificant for surfaces that are already at melting point, see section 3.6 in https://doi.org/10.1002/met.2134 and supporting citations, the exception being HEAVY rain only LOW TEMPERATURE firn, see Harper et al 2024? GRL https://doi.org/10.1029/2023GL103654
43-44 "washing away surface debris" shown by what study? citation needed
Table 1, CARRA 1971–2000 but CARRA data start in 1991?
105-106 "previously used to evaluate climate models" also https://doi.org/10.1002/met.2134 and https://doi.org/10.1029/2021GL092942
106 and new GEUS AWS data citation https://doi.org/10.5194/essd-2025-687
108 "hard to compare with precipitation in a climate model" true :-)
for CARRA data, in addition to the Yang et al citation, pls include
Schyberg, H., Yang, X., Køltzow, M. A. Ø., Amstrup, B., Bakketun, Å., Bazile, E., Bojarova, J., e., B., Dahlgren, P., Hagelin, S., Homleid, M., Horányi, A., Høyer, J., Johansson, Å., Killie, M. A., Körnich, H., Le,Moigne,P., Lindskog, M., Manninen, T., Nielsen,Englyst,P., Nielsen, K. P., Olsson, E., Palmason, B., Peralta,Aros,C., Randriamampianina, R., Samuelsson, P., Stappers, R., Støylen, E., Thorsteinsson, S., Valkonen, T., and Wang, Z. Q.: Arctic regional reanalysis on single levels from 1991 to present, https://doi.org/10.24381/cds.713858f6, 2020.
118 "outperforms ERA5 when comparing the two datasets with in-situ observations", for rainfall using ON-ICE observations, not only CARRA but other models, https://doi.org/10.1002/met.2134
Figures 3 and7, like the figures!, but the colors need to change, avoid bright yellow and no greens. Orange, magenta and could also be dashed lines, and why not box plots using seaborne or violin plots to make a great plot even better? Instead of 1,2,3... use names like NE, all
Figure 4 important results. Comments on sea ice decline effect for change in precipitation needed if not already there.
198 "a large fraction", include a quantity
Figure 6 using a colorblind sensitive color palette? Seems not. I'm not color blind (at least I don't think so), but it's the norm anyway to not combine green and red-sh colors. And thin rain fraction of total precip is more standard than snow fraction of total precip. Really want a number for the whole ice sheet within the ice mask, and a time series graphic
249 "robust across most models." or "consistent across all models"... is there a statistical test to help here?
254 "we find increases" io "we see positive changes"
274 "CARRA has shown clear advantages to other reanalysis products (Køltzow et al., 2022)" include the Greenland specific study reaching this conclusion https://doi.org/10.1002/met.2134
275 "performs better in other regions." better than ___?, could be something like "has smaller differences relative to observations in other regions."
276 "located in or near" io "located in"
283 "However,", see the %/K points above in this review.
293 "(Doyle et al., 2015)"? io "(Doyle et al., 2014)"
299 something like "Our work, consistent with theory, finds that the GrIS faces a wetter future in all regions," io "The GrIS faces a wetter future in all regions,"
301 avoid/spell out abbreviations in conclusions, "SSP".