Abstract
To date, the treatment of permafrost in global climate models has been simplified due to the prevailing uncertainties in the processes involving frozen ground. In this study, we improved the modeling of permafrost processes in a state-of-the-art climate model by taking into account some of the relevant physical properties of soil such as changes in the thermophysical properties due to soil freezing. As a result, the improved version of the global land surface model was able to reproduce a more realistic permafrost distribution at the southern limit of the permafrost area by increasing the freezing of soil moisture in winter. The improved modeling of permafrost processes also had a significant effect on future projections. Using the conventional formulation, the predicted cumulative reduction of the permafrost area by year 2100 was approximately 60% (40–80% range of uncertainty from a multi-model ensemble) in the RCP8.5 scenario, while with the improved formulation, the reduction was approximately 35% (20–50%). Our results indicate that the improved treatment of permafrost processes in global climate models is important to ensuring more reliable future projections.
Highlights
Global warming is expected to produce a thawing of the permafrost (Koven et al 2013; Slater and Lawrence 2013; Vaks et al 2013; Koven et al 2015; McGuire et al 2018)
The tendency of the permafrost area in the improved scheme to be larger and closer to the observed area than is the case for the conventional scheme is evident in all the simulation results forced by the five Global climate model (GCM)
5 Conclusions By refining the process associated with the freezing and thawing of soil moisture—which has been simplified in previous global climate models—the reproducibility of the model used here improved noticeably (Figs. 2 and 4)
Summary
Global warming is expected to produce a thawing of the permafrost (Koven et al 2013; Slater and Lawrence 2013; Vaks et al 2013; Koven et al 2015; McGuire et al 2018). Previous research (Lawrence et al 2008; Saito 2008a; Saito 2008b; Saito 2011; Chadburn et al 2015; Melton et al 2019) has recognized the importance of taking into account changes in thermodynamic quantities due to the freezing of soil moisture and the physical characteristics of the organic layer near the ground surface, and presence of unfrozen water in order to obtain more realistic permafrost distributions in simulations using global climate models This previous research with MATSIRO (Saito 2008a, 2008b, 2011) involved only historical or ideal future simulations at particular points where observational data were available (e.g., Utqiagvik, formerly known as Barrow) or conducted only historical global simulations. Neither the impact of the proposed improvements in the modeling of the physical properties of permafrost processes nor the uncertainties in the projection of future atmospheric forcing were evaluated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
