Simulated high-latitude soil thermal dynamics during the past 4 decades

S. Peng; P. Ciais; G Krinner; T. Wang; I. Gouttevin; A. D. McGuire; D. Lawrence; E. Burke; X. Chen; B. Decharme; C. Koven; A. McDougall; A. Rinke; K. Saito; W. Zhang; R. Alkama; T. J. Bohn; C. Delire; T. Hajima; D. Ji; D. P. Lettenmaier; P. A. Miller; J. C. Moore; B. Smith; T. Sueyoshi

doi:10.5194/tc-10-179-2016

Simulated high-latitude soil thermal dynamics during the past 4 decades

S. Peng, P. Ciais, G Krinner, T. Wang, I. Gouttevin, A. D. McGuire, D. Lawrence, E. Burke, X. Chen, B. Decharme, C. Koven, A. McDougall, A. Rinke, K. Saito, W. Zhang, R. Alkama, T. J. Bohn, C. Delire, T. Hajima, D. JiD. P. Lettenmaier, P. A. Miller, J. C. Moore, B. Smith, T. Sueyoshi

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Abstract

Soil temperature (T_s/change is a key indicator of the dynamics of permafrost. On seasonal and interannual timescales, the variability of Ts determines the activelayer depth, which regulates hydrological soil properties and biogeochemical processes. On the multi-decadal scale, increasing Ts not only drives permafrost thaw/retreat but can also trigger and accelerate the decomposition of soil organic carbon. The magnitude of permafrost carbon feedbacks is thus closely linked to the rate of change of soil thermal regimes. In this study, we used nine process-based ecosystem models with permafrost processes, all forced by different observation-based climate forcing during the period 1960-2000, to characterize the warming rate of Ts in permafrost regions. There is a large spread of Ts trends at 20 cm depth across the models, with trend values ranging from 0.010 ± 0.003 to 0.031 ± 0.005 °C yr^-1. Most models show smaller increase in Ts with increasing depth. Air temperature (Ta/and longwave downward radiation (LWDR) are the main drivers of Ts trends, but their relative contributions differ amongst the models. Different trends of LWDR used in the forcing of models can explain 61 % of their differences in Ts trends, while trends of Ta only explain 5 % of the differences in Ts trends. Uncertain climate forcing contributes a larger uncertainty in Ts trends (0.021 ± 0.008 °C yr^-1, mean ± standard deviation) than the uncertainty of model structure (0.012 ± 0.001 °C yr^-1/, diagnosed from the range of response between different models, normalized to the same forcing. In addition, the loss rate of near-surface permafrost area, defined as total area where the maximum seasonal active-layer thickness (ALT) is less than 3 m loss rate, is found to be significantly correlated with the magnitude of the trends of Ts at 1 m depth across the models (R D-0:85, P = 0:003), but not with the initial total nearsurface permafrost area (R =-0:30, P = 0:438). The sensitivity of the total boreal near-surface permafrost area to Ts at 1 m is estimated to be of-2.80 ± 0.67 million km2 °C^-1. Finally, by using two long-term LWDR data sets and relationships between trends of LWDR and Ts across models, we infer an observation-constrained total boreal near-surface permafrost area decrease comprising between 39 ± 14 × 103 and 75 ± 14 × 103 km2 yr^-1 from 1960 to 2000. This corresponds to 9-18 % degradation of the current permafrost area.

Original language	English
Journal	The Cryosphere
Volume	10
Issue number	1
Pages (from-to)	179-192
Number of pages	14
ISSN	1994-0416
DOIs	https://doi.org/10.5194/tc-10-179-2016
Publication status	Published - 2016
Externally published	Yes

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Peng, S., Ciais, P., Krinner, G., Wang, T., Gouttevin, I., D. McGuire, A., Lawrence, D., Burke, E., Chen, X., Decharme, B., Koven, C., McDougall, A., Rinke, A., Saito, K., Zhang, W., Alkama, R., J. Bohn, T., Delire, C., Hajima, T., ... Sueyoshi, T. (2016). Simulated high-latitude soil thermal dynamics during the past 4 decades. The Cryosphere, 10(1), 179-192. https://doi.org/10.5194/tc-10-179-2016

Peng, S, Ciais, P, Krinner, G, Wang, T, Gouttevin, I, D. McGuire, A, Lawrence, D, Burke, E, Chen, X, Decharme, B, Koven, C, McDougall, A, Rinke, A, Saito, K, Zhang, W, Alkama, R, J. Bohn, T, Delire, C, Hajima, T, Ji, D, P. Lettenmaier, D, A. Miller, P, C. Moore, J, Smith, B & Sueyoshi, T 2016, 'Simulated high-latitude soil thermal dynamics during the past 4 decades', The Cryosphere, vol. 10, no. 1, pp. 179-192. https://doi.org/10.5194/tc-10-179-2016

@article{845f8a1fd6794f57a8a7c3cfeaa9b342,

title = "Simulated high-latitude soil thermal dynamics during the past 4 decades",

abstract = "Soil temperature (Ts/change is a key indicator of the dynamics of permafrost. On seasonal and interannual timescales, the variability of Ts determines the activelayer depth, which regulates hydrological soil properties and biogeochemical processes. On the multi-decadal scale, increasing Ts not only drives permafrost thaw/retreat but can also trigger and accelerate the decomposition of soil organic carbon. The magnitude of permafrost carbon feedbacks is thus closely linked to the rate of change of soil thermal regimes. In this study, we used nine process-based ecosystem models with permafrost processes, all forced by different observation-based climate forcing during the period 1960-2000, to characterize the warming rate of Ts in permafrost regions. There is a large spread of Ts trends at 20 cm depth across the models, with trend values ranging from 0.010 ± 0.003 to 0.031 ± 0.005 °C yr-1. Most models show smaller increase in Ts with increasing depth. Air temperature (Ta/and longwave downward radiation (LWDR) are the main drivers of Ts trends, but their relative contributions differ amongst the models. Different trends of LWDR used in the forcing of models can explain 61 % of their differences in Ts trends, while trends of Ta only explain 5 % of the differences in Ts trends. Uncertain climate forcing contributes a larger uncertainty in Ts trends (0.021 ± 0.008 °C yr-1, mean ± standard deviation) than the uncertainty of model structure (0.012 ± 0.001 °C yr-1/, diagnosed from the range of response between different models, normalized to the same forcing. In addition, the loss rate of near-surface permafrost area, defined as total area where the maximum seasonal active-layer thickness (ALT) is less than 3 m loss rate, is found to be significantly correlated with the magnitude of the trends of Ts at 1 m depth across the models (R D-0:85, P = 0:003), but not with the initial total nearsurface permafrost area (R =-0:30, P = 0:438). The sensitivity of the total boreal near-surface permafrost area to Ts at 1 m is estimated to be of-2.80 ± 0.67 million km2 °C-1. Finally, by using two long-term LWDR data sets and relationships between trends of LWDR and Ts across models, we infer an observation-constrained total boreal near-surface permafrost area decrease comprising between 39 ± 14 × 103 and 75 ± 14 × 103 km2 yr-1 from 1960 to 2000. This corresponds to 9-18 % degradation of the current permafrost area.",

author = "S. Peng and P. Ciais and G Krinner and T. Wang and I. Gouttevin and {D. McGuire}, A. and D. Lawrence and E. Burke and X. Chen and B. Decharme and C. Koven and A. McDougall and A. Rinke and K. Saito and W. Zhang and R. Alkama and {J. Bohn}, T. and C. Delire and T. Hajima and D. Ji and {P. Lettenmaier}, D. and {A. Miller}, P. and {C. Moore}, J. and B. Smith and T. Sueyoshi",

year = "2016",

doi = "10.5194/tc-10-179-2016",

language = "English",

volume = "10",

pages = "179--192",

journal = "The Cryosphere",

issn = "1994-0416",

publisher = "Copernicus GmbH",

number = "1",

}

TY - JOUR

T1 - Simulated high-latitude soil thermal dynamics during the past 4 decades

AU - Peng, S.

AU - Ciais, P.

AU - Krinner, G

AU - Wang, T.

AU - Gouttevin, I.

AU - D. McGuire, A.

AU - Lawrence, D.

AU - Burke, E.

AU - Chen, X.

AU - Decharme, B.

AU - Koven, C.

AU - McDougall, A.

AU - Rinke, A.

AU - Saito, K.

AU - Zhang, W.

AU - Alkama, R.

AU - J. Bohn, T.

AU - Delire, C.

AU - Hajima, T.

AU - Ji, D.

AU - P. Lettenmaier, D.

AU - A. Miller, P.

AU - C. Moore, J.

AU - Smith, B.

AU - Sueyoshi, T.

PY - 2016

Y1 - 2016

N2 - Soil temperature (Ts/change is a key indicator of the dynamics of permafrost. On seasonal and interannual timescales, the variability of Ts determines the activelayer depth, which regulates hydrological soil properties and biogeochemical processes. On the multi-decadal scale, increasing Ts not only drives permafrost thaw/retreat but can also trigger and accelerate the decomposition of soil organic carbon. The magnitude of permafrost carbon feedbacks is thus closely linked to the rate of change of soil thermal regimes. In this study, we used nine process-based ecosystem models with permafrost processes, all forced by different observation-based climate forcing during the period 1960-2000, to characterize the warming rate of Ts in permafrost regions. There is a large spread of Ts trends at 20 cm depth across the models, with trend values ranging from 0.010 ± 0.003 to 0.031 ± 0.005 °C yr-1. Most models show smaller increase in Ts with increasing depth. Air temperature (Ta/and longwave downward radiation (LWDR) are the main drivers of Ts trends, but their relative contributions differ amongst the models. Different trends of LWDR used in the forcing of models can explain 61 % of their differences in Ts trends, while trends of Ta only explain 5 % of the differences in Ts trends. Uncertain climate forcing contributes a larger uncertainty in Ts trends (0.021 ± 0.008 °C yr-1, mean ± standard deviation) than the uncertainty of model structure (0.012 ± 0.001 °C yr-1/, diagnosed from the range of response between different models, normalized to the same forcing. In addition, the loss rate of near-surface permafrost area, defined as total area where the maximum seasonal active-layer thickness (ALT) is less than 3 m loss rate, is found to be significantly correlated with the magnitude of the trends of Ts at 1 m depth across the models (R D-0:85, P = 0:003), but not with the initial total nearsurface permafrost area (R =-0:30, P = 0:438). The sensitivity of the total boreal near-surface permafrost area to Ts at 1 m is estimated to be of-2.80 ± 0.67 million km2 °C-1. Finally, by using two long-term LWDR data sets and relationships between trends of LWDR and Ts across models, we infer an observation-constrained total boreal near-surface permafrost area decrease comprising between 39 ± 14 × 103 and 75 ± 14 × 103 km2 yr-1 from 1960 to 2000. This corresponds to 9-18 % degradation of the current permafrost area.

AB - Soil temperature (Ts/change is a key indicator of the dynamics of permafrost. On seasonal and interannual timescales, the variability of Ts determines the activelayer depth, which regulates hydrological soil properties and biogeochemical processes. On the multi-decadal scale, increasing Ts not only drives permafrost thaw/retreat but can also trigger and accelerate the decomposition of soil organic carbon. The magnitude of permafrost carbon feedbacks is thus closely linked to the rate of change of soil thermal regimes. In this study, we used nine process-based ecosystem models with permafrost processes, all forced by different observation-based climate forcing during the period 1960-2000, to characterize the warming rate of Ts in permafrost regions. There is a large spread of Ts trends at 20 cm depth across the models, with trend values ranging from 0.010 ± 0.003 to 0.031 ± 0.005 °C yr-1. Most models show smaller increase in Ts with increasing depth. Air temperature (Ta/and longwave downward radiation (LWDR) are the main drivers of Ts trends, but their relative contributions differ amongst the models. Different trends of LWDR used in the forcing of models can explain 61 % of their differences in Ts trends, while trends of Ta only explain 5 % of the differences in Ts trends. Uncertain climate forcing contributes a larger uncertainty in Ts trends (0.021 ± 0.008 °C yr-1, mean ± standard deviation) than the uncertainty of model structure (0.012 ± 0.001 °C yr-1/, diagnosed from the range of response between different models, normalized to the same forcing. In addition, the loss rate of near-surface permafrost area, defined as total area where the maximum seasonal active-layer thickness (ALT) is less than 3 m loss rate, is found to be significantly correlated with the magnitude of the trends of Ts at 1 m depth across the models (R D-0:85, P = 0:003), but not with the initial total nearsurface permafrost area (R =-0:30, P = 0:438). The sensitivity of the total boreal near-surface permafrost area to Ts at 1 m is estimated to be of-2.80 ± 0.67 million km2 °C-1. Finally, by using two long-term LWDR data sets and relationships between trends of LWDR and Ts across models, we infer an observation-constrained total boreal near-surface permafrost area decrease comprising between 39 ± 14 × 103 and 75 ± 14 × 103 km2 yr-1 from 1960 to 2000. This corresponds to 9-18 % degradation of the current permafrost area.

U2 - 10.5194/tc-10-179-2016

DO - 10.5194/tc-10-179-2016

M3 - Journal article

SN - 1994-0416

VL - 10

SP - 179

EP - 192

JO - The Cryosphere

JF - The Cryosphere

IS - 1

ER -

Simulated high-latitude soil thermal dynamics during the past 4 decades

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