Preprints
https://doi.org/10.5194/egusphere-2024-2445
https://doi.org/10.5194/egusphere-2024-2445
13 Aug 2024
 | 13 Aug 2024
Status: this preprint is open for discussion.

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

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

Abstract. The Arctic winter is disproportionately vulnerable to climate warming and approximately 1700 Gt of carbon stored in high latitude permafrost ecosystems is at risk of degradation in the future due to enhanced microbial activity. Few studies have been directed at high-latitude cold season land-atmosphere processes and it is suggested that the contribution of winter season greenhouse gas (GHG) fluxes to the annual carbon budget may have been underestimated. Snow, acting as a thermal blanket, influences Arctic soil temperatures during winter and parameters such as snow effective thermal conductivity (Keff) are not well constrained in land surface models which impacts our ability to accurately simulate wintertime soil carbon emissions. A point-model version of the Community Land Model (CLM5.0) forced by an ensemble of NA-CORDEX (North American Coordinated Regional Downscaling Experiment) future climate realisations (RCP 4.5 and 8.5) indicates that median winter CO2 emissions will have more than tripled by the end of the century (2066–2096) under RCP 8.5 and using a Keff parameterisation which is more representative of Arctic snowpack. Implementing this Keff parameterisation increases simulated winter CO2 in the latter half of the century (2066–2096) by 130 % and CH4 flux by 50 % under RCP 8.5 compared to the widely used default Keff parameterisation. The influence of snow Keff parameterisation within CLM5.0 on future simulated CO2 and CH4 is at least as significant, if not more so, than climate variability from a range of NA-CORDEX projections to 2100. Furthermore, CLM5.0 simulations show that enhanced future air and soil temperatures increases the duration of the early winter (Sept–Oct) zero-curtain, a crucial period of soil carbon emissions, by up to a month and recent increases in both zero-curtain and winter CO2 emissions appear set to continue to 2100. Modelled winter soil temperatures and carbon emissions demonstrate the importance of climate mitigation in preventing a significant increase in winter carbon emissions from the Arctic in the future.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Johnny Rutherford, Nick Rutter, Leanne Wake, and Alex Cannon

Status: open (until 30 Dec 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2024-2445', Jeff Welker, 20 Aug 2024 reply
Johnny Rutherford, Nick Rutter, Leanne Wake, and Alex Cannon
Johnny Rutherford, Nick Rutter, Leanne Wake, and Alex Cannon

Viewed

Total article views: 396 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
269 75 52 396 9 12
  • HTML: 269
  • PDF: 75
  • XML: 52
  • Total: 396
  • BibTeX: 9
  • EndNote: 12
Views and downloads (calculated since 13 Aug 2024)
Cumulative views and downloads (calculated since 13 Aug 2024)

Viewed (geographical distribution)

Total article views: 409 (including HTML, PDF, and XML) Thereof 409 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 06 Dec 2024
Download
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), causes uncertainty in projected carbon emission simulations. Improved snow conductivity parameterization in CLM5.0 significantly increases predicted winter CO2 emissions to 2100.