Snow thermal conductivity controls future winter carbon emissions in shrub–tundra

Rutherford, Johnny; Rutter, Nick; Wake, Leanne; Cannon, Alex J.

doi:https://doi.org/10.5194/bg-22-5031-2025

Articles | Volume 22, issue 18

https://doi.org/10.5194/bg-22-5031-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-22-5031-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 22, issue 18

Research article

|

29 Sep 2025

Research article |

| 29 Sep 2025

Snow thermal conductivity controls future winter carbon emissions in shrub–tundra

Johnny Rutherford, Nick Rutter, Leanne Wake, and Alex J. Cannon

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Final revised paper (published on 29 Sep 2025)
Preprint (discussion started on 13 Aug 2024)

Interactive discussion

Status: closed

CC1:
'Comment on egusphere-2024-2445', Jeff Welker, 20 Aug 2024

This is a very important paper and set of discoveries.
However, it is missing recognition of the massive set of studies that discovered and addressed these issues going back to the original US ITEX program at Toolik AK and the NSF ATLAS (Arctic Transition in the Land Atmosphere System) that should be included.
Those being:

Jones, M. H., Fahnestock, J. T., Walker, D. A., Walker, M. D., and Welker, J. M. (1998) Carbon dioxide fluxes in moist and dry arctic tundra during the snow-free season: responses to increases in summer temperature and winter snow accumulation. Arctic and Alpine Research 30: 373-380.

Fahnestock, J. T., Jones, M. H., Brooks, P. D., Walker, D. A., and Welker, J. M. (1998) Winter and early spring CO₂flux from tundra communities of northern Alaska. Journal of Geophysical Research 102 (D22): 29925-29931.

Fahnestock, J. T., Jones, M. H., Brooks, P. D., and Welker, J. M. (1999) Significant CO₂emissions from tundra soils during winter: Implications for annual carbon budgets of arctic communities. Global Biogeochemical Cycles 13: 775-779.

Welker, J. M., Fahnestock, J. T., and Jones, M. H. (2000) Annual CO₂ flux from dry and moist arctic tundra: Field responses to increases in summer temperature and winter snow depth. Climatic Change 44: 139-150.

Schimel, J. S., Bilbrough, C. B., and Welker, J. M. (2004) Increased snow depth affects microbial activity and nitrogen mineralization in two Arctic tundra communities. Soil Biology and Biochemistry 36: 217-227.

Schimel, J., Fahnestock, J., Michaelson, G., Milkan, C., Ping, C, Romanovsky, V., and Welker, J. M. (2006) Cold-season production of CO₂ in Arctic soils: Can laboratory and field estimates be reconciled through a simple modeling approach? Arctic, Antarctic and Alpine Research 38(2): 249-255

Sullivan, P. F., Arens, S., Sveinbjörnsson, B., and Welker, J. M. (2010) Modeling the seasonality of belowground respiration along an elevation gradient in the western Chugach Mountains, Alaska. Biogeochemistry 101(1-3): 61-75.

Lupascu, M., Czimczik, C. I., Welker, M., Cooper, L., and Welker, J. M. (2018) Winter ecosystem respiration and sources of CO₂ from the High Arctic tundra of Svalbard: Response to a deeper snow experiment. JGR Biogeosciences DOI.org/10.1029/ 2018JG004396.

Pedron, S., Xu, X., Walker, J., Welker, J. M., Klein, E. and Czimczik, C. (2021) Time-integrated Collection of CO₂for ¹⁴C Analysis from Soils. Radiocarbon DOI: 10.101/RDC.2021.42.

Pedron, S. A., Welker, J. M., Euskirchen, E., Klein, E. S., Walker, J. C., Xu, X., and Czimczik, C. I. (2022) Closing the winter gap-Year-round measurements of soil CO₂ emission sources in Arctic Tundra. Geophysical Research Letters doi.org/10.1029/2021GL097347.

Citation: https://doi.org/10.5194/egusphere-2024-2445-CC1
- AC1: 'Reply on CC1', Johnny Rutherford, 12 Jun 2025
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2445/egusphere-2024-2445-AC1-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2024-2445-AC1
RC1:
'Comment on egusphere-2024-2445', Katharina Jentzsch, 20 Apr 2025

The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2445/egusphere-2024-2445-RC1-supplement.pdf

Citation: https://doi.org/10.5194/egusphere-2024-2445-RC1
- AC2: 'Reply on RC1', Johnny Rutherford, 12 Jun 2025
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2445/egusphere-2024-2445-AC2-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2024-2445-AC2
- AC4: 'References', Johnny Rutherford, 12 Jun 2025
  
  Callaghan, T. V., Johansson, M., Brown, R. D., Groisman, P. Y., Labba, N., Radionov, V., Bradley, R. S., Blangy, S., Bulygina, O. N., Christensen, T. R., Colman, J. E., Essery, R. L. H., Forbes, B. C., Forchhammer, M. C., Golubev, V. N., Honrath, R. E., Juday, G. P., Meshcherskaya, A. V., Phoenix, G. K., Pomeroy, J., Rautio, A., Robinson, D. A., Schmidt, N. M., Serreze, M. C., Shevchenko, V. P., Shiklomanov, A. I., Shmakin, A. B., Sköld, P., Sturm, M., Woo, M.-K. & Wood, E. F. 2011. Multiple Effects of Changes in Arctic Snow Cover. AMBIO, 40, 32-45.
  Jordan, R. E. 1991. A One-Dimensional Temperature Model for a Snow Cover: Technical Documentation for Sntherm. 89.
  Sturm, M., Holmgren, J., König, M. & Morris, K. 1997. The Thermal Conductivity of Seasonal Snow. Journal of Glaciology, 43, 26-41.
  
  Citation: https://doi.org/10.5194/egusphere-2024-2445-AC4
RC2:
'Comment on egusphere-2024-2445', Anonymous Referee #2, 26 May 2025

Rutherford and others study the consequences of using more realistic snow thermal parameters and biogeochemical temperature sensitivities for future carbon dioxide and methane release in a tundra ecosystem. The results make some interesting points but I was unsure why the particular site was chosen if no data are being compared against model results, especially as the earlier simulation period overlaps with the present day. As such it is unclear if the base model is realistic in the first place, which is critical for defensible future scenarios. I recommend trying to use existing observations, especially for things like snow duration and soil temperature that are measurable, for ensuring that model results are realistic before moving on to the important topic of making the model more realistic.

86: what does ‘not appropriate’ mean in this context? Why is it not appropriate?
161: note the spread of Q values…these are related to the chemical composition of the respired material and can change quite a lot, especially with respect to more labile carbon inputs that are easier to decompose.
222: note reference formatting error
The analysis in Figure 3 is interesting but for the particular site is there a measured data record to compare against, especially because the 2016-2046 averaging period includes the present day? It’s critical to understand how well modeled values match measurements to help instill confidence in the future projections.

Citation: https://doi.org/10.5194/egusphere-2024-2445-RC2
- AC3: 'Reply on RC2', Johnny Rutherford, 12 Jun 2025
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2445/egusphere-2024-2445-AC3-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2024-2445-AC3

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Reconsider after major revisions (12 Jun 2025) by Paul Stoy

AR by Johnny Rutherford on behalf of the Authors (13 Jun 2025) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (13 Jun 2025) by Paul Stoy

RR by Anonymous Referee #2 (25 Jun 2025)

ED: Publish subject to minor revisions (review by editor) (25 Jun 2025) by Paul Stoy

AR by Johnny Rutherford on behalf of the Authors (07 Jul 2025) Author's response Author's tracked changes Manuscript

ED: Publish as is (09 Jul 2025) by Paul Stoy

AR by Johnny Rutherford on behalf of the Authors (14 Jul 2025)

Short summary

The Arctic winter is vulnerable to climate warming, and ~1700 Gt of carbon stored in high-latitude permafrost ecosystems is at risk of degradation in the future due to enhanced microbial activity. Poorly represented cold season processes, such as the simulation of snow thermal conductivity in land surface models (LSMs), cause uncertainty in projected carbon emission simulations. Improved snow conductivity parameterization in CLM5.0 significantly increases predicted winter CO₂ emissions to 2100.

Snow thermal conductivity controls future winter carbon emissions in shrub–tundra

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