| Title | Evaluating permafrost physics in the Coupled Model Intercomparison Project 6 (CMIP6) models and their sensitivity to climate change |
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| Author | Burke, E J; Zhang, Y ; Krinner, G |
| Source | The Cryosphere vol. 14, issue 9, 2020 p. 3155-3174, https://doi.org/10.5194/tc-14-3155-2020  Open Access |
| Image |  |
| Year | 2020 |
| Alt Series | Natural Resources Canada, Contribution Series 20200508 |
| Publisher | Copernicus GmbH |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Subjects | surficial geology/geomorphology; soils science; environmental geology; Nature and Environment; Science and Technology; permafrost; climate effects; climate, arctic; temperature; modelling; models; soil
profiles; terrain sensitivity; Coupled Model Intercomparison Project 6 (CMIP6); Climate change; permafrost thaw |
| Illustrations | schematic cross-sections; tables; plots; bar graphs; sketch maps; models |
| Program | Canada Centre for Remote Sensing Optical methods and applications |
| Released | 2020 09 16 |
| Abstract | Permafrost is a ubiquitous phenomenon in the Arctic. Its future evolution is likely to control changes in northern high-latitude hydrology and biogeochemistry. Here we evaluate the permafrost dynamics
in the global models participating in the Coupled Model Intercomparison Project (present generation - CMIP6; previous generation - CMIP5) along with the sensitivity of permafrost to climate change. Whilst the northern high-latitude air temperatures
are relatively well simulated by the climate models, they do introduce a bias into any subsequent model estimate of permafrost. Therefore evaluation metrics are defined in relation to the air temperature. This paper shows that the climate, snow and
permafrost physics of the CMIP6 multi-model ensemble is very similar to that of the CMIP5 multi-model ensemble. The main differences are that a small number of models have demonstrably better snow insulation in CMIP6 than in CMIP5 and a small number
have a deeper soil profile. These changes lead to a small overall improvement in the representation of the permafrost extent. There is little improvement in the simulation of maximum summer thaw depth between CMIP5 and CMIP6. We suggest that more
models should include a better-resolved and deeper soil profile as a first step towards addressing this. We use the annual mean thawed volume of the top 2m of the soil defined from the model soil profiles for the permafrost region to quantify changes
in permafrost dynamics. The CMIP6 models project that the annual mean frozen volume in the top 2m of the soil could decrease by 10 %-40%C1 of global mean surface air temperature increase. |
| Summary | (Plain Language Summary, not published)
This study examines permafrost dynamics in global climate models, focusing on the latest generation (CMIP6) and the previous one (CMIP5). Permafrost,
which is frozen ground, is widespread in the Arctic and plays a vital role in northern high-latitude hydrology and biogeochemistry. The research aims to evaluate how well these models represent permafrost and how sensitive it is to climate
change.
The findings reveal that while the models perform well in simulating air temperatures in the northern high latitudes, there are biases when estimating permafrost extent. Comparing CMIP6 to CMIP5, the study shows that most aspects of
climate, snow, and permafrost physics remain similar. However, a few CMIP6 models have improved snow insulation and deeper soil profiles, resulting in a slight enhancement in representing permafrost extent.
Despite these improvements, there is
limited progress in modeling the maximum summer thaw depth. The research suggests that better-resolved and deeper soil profiles in more models could address this issue.
Overall, this work provides insights into the current state of permafrost
representation in climate models and highlights the importance of understanding permafrost dynamics in the face of ongoing climate change, as it can impact hydrology and biogeochemical processes in the Arctic. |
| GEOSCAN ID | 327428 |
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