LGM permafrost distribution: how well can the latest PMIP multi-model ensembles perform reconstruction?

Saitô, Kazuyuki; Sueyoshi, Tetsuo; Marchenko, S. S.; Romanovsky, V. E.; Otto‐Bliesner, Bette L.; Walsh, John E.; Bigelow, Nancy H.; Hendricks, A.; Yoshikawa, Kenji

doi:10.5194/cp-9-1697-2013

Cited by 42 publications

(60 citation statements)

References 56 publications

(88 reference statements)

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“…The modeled permafrost extent is in even better agreement with the continuous permafrost extent estimates in Vandenberghe et al (2014). Over North America, permafrost is simulated south of the LIS mainly over the Rocky Mountains, in very close agreement with reconstructions (Vanden- berghe et al, 2014) and PMIP3 ensemble model estimates for the LGM (Saito et al, 2013). At LGM the modeled permafrost area is around 21 million square kilometers, lower than the mode of PMIP3 models, 29.5 million square kilometers (Saito et al, 2013), but within the PMIP3 ensemble range (20-37 million square kilometers).…”

Section: Permafrost-ice-sheet Evolution Over the Last Glacial Cyclesupporting

confidence: 70%

“…Over North America, permafrost is simulated south of the LIS mainly over the Rocky Mountains, in very close agreement with reconstructions (Vanden- berghe et al, 2014) and PMIP3 ensemble model estimates for the LGM (Saito et al, 2013). At LGM the modeled permafrost area is around 21 million square kilometers, lower than the mode of PMIP3 models, 29.5 million square kilometers (Saito et al, 2013), but within the PMIP3 ensemble range (20-37 million square kilometers). Some differences are probably due to the underestimation of permafrost extent over Europe and larger ice sheet in Siberia than prescribed in CMIP3 (Fig.…”

Section: Permafrost-ice-sheet Evolution Over the Last Glacial Cyclesupporting

confidence: 65%

“…As expected given the negative temperature bias over central Eurasia, simulated permafrost extends too far south over southwestern Russia. The skill of the model at reproducing present-day permafrost extent is comparable to the skill of PMIP3 models (Saito et al, 2013).…”

Section: Model Performance For Present Daymentioning

confidence: 52%

“…Present-day modeled NH permafrost area is around 15 million square kilometers, which is very close to the mode of the PMIP3 models (Saito et al, 2013). The empirical estimates of area of continuous permafrost are around 10 million square kilometers; including also the discontinuous per- mafrost increases this value to approximately 21.5 million square kilometers.…”

Section: Permafrost-ice-sheet Evolution Over the Last Glacial Cyclementioning

confidence: 55%

“…present south of the margin of the Laurentide ice sheet (Saito et al, 2013;Vandenberghe et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

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Coupled Northern Hemisphere permafrost–ice-sheet evolution over the last glacial cycle

Willeit

Ganopolski

2015

Clim. Past

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Abstract. Permafrost influences a number of processes which are relevant for local and global climate. For example, it is well known that permafrost plays an important role in global carbon and methane cycles. Less is known about the interaction between permafrost and ice sheets. In this study a permafrost module is included in the Earth system model CLIMBER-2, and the coupled Northern Hemisphere (NH) permafrost-ice-sheet evolution over the last glacial cycle is explored.The model performs generally well at reproducing present-day permafrost extent and thickness. Modeled permafrost thickness is sensitive to the values of ground porosity, thermal conductivity and geothermal heat flux. Permafrost extent at the Last Glacial Maximum (LGM) agrees well with reconstructions and previous modeling estimates.Present-day permafrost thickness is far from equilibrium over deep permafrost regions. Over central Siberia and the Arctic Archipelago permafrost is presently up to 200-500 m thicker than it would be at equilibrium. In these areas, present-day permafrost depth strongly depends on the past climate history and simulations indicate that deep permafrost has a memory of surface temperature variations going back to at least 800 ka.Over the last glacial cycle permafrost has a relatively modest impact on simulated NH ice sheet volume except at LGM, when including permafrost increases ice volume by about 15 m sea level equivalent in our model. This is explained by a delayed melting of the ice base from below by the geothermal heat flux when the ice sheet sits on a porous sediment layer and permafrost has to be melted first. Permafrost affects ice sheet dynamics only when ice extends over areas covered by thick sediments, which is the case at LGM.

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Section: Permafrost-ice-sheet Evolution Over the Last Glacial Cyclesupporting

confidence: 70%

Section: Permafrost-ice-sheet Evolution Over the Last Glacial Cyclesupporting

confidence: 65%

Section: Model Performance For Present Daymentioning

confidence: 52%

Section: Permafrost-ice-sheet Evolution Over the Last Glacial Cyclementioning

confidence: 55%

“…present south of the margin of the Laurentide ice sheet (Saito et al, 2013;Vandenberghe et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

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Coupled Northern Hemisphere permafrost–ice-sheet evolution over the last glacial cycle

Willeit

Ganopolski

2015

Clim. Past

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Mid‐Holocene permafrost: Results from CMIP5 simulations

Liu

Jiang

2016

JGR Atmospheres

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Distribution of frozen ground and active layer thickness in the Northern Hemisphere during the mid‐Holocene (MH) and differences with respect to the preindustrial (PI) were investigated here using the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Two typical diagnostic methods, respectively, based on soil temperature (Ts based; a direct method) and air temperature (Ta based; an indirect method) were employed to classify categories and extents of frozen ground. In relation to orbitally induced changes in climate and in turn freezing and thawing indices, the MH permafrost extent was 20.5% (1.8%) smaller than the PI, whereas seasonally frozen ground increased by 9.2% (0.8%) in the Northern Hemisphere according to the Ts‐based (Ta‐based) method. Active layer thickness became larger, but by ≤ 1.0 m in most of permafrost areas during the MH. Intermodel disagreement remains within areas of permafrost boundary by both the Ts‐based and Ta‐based results, with the former demonstrating less agreement among the CMIP5 models because of larger variation in land model abilities to represent permafrost processes. However, both the methods were able to reproduce the MH relatively degenerated permafrost and increased active layer thickness (although with smaller magnitudes) as observed in data reconstruction. Disparity between simulation and reconstruction was mainly found in the seasonally frozen ground regions at low to middle latitudes, where the reconstruction suggested a reduction of seasonally frozen ground extent to the north, whereas the simulation demonstrated a slightly expansion to the south for the MH compared to the PI.

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An improved method for calculating the freezing/thawing index using monthly and annual temperature data

Liu

Feng

Huang

2021

Intl Journal of Climatology

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Changes in soil thermal regimes in cold climates have widespread impacts on hydrology, ecology, and the carbon cycle. The annual freezing and thawing index, which is generally calculated using daily temperature, has been widely used to estimate the freezing depth, active layer thickness, and the distribution of permafrost. However, continuous and reliable daily temperature data are scarce in cold climates, while monthly and annual temperature data are more readily available. If daily temperature data are unavailable, these indices can be estimated based on monthly or annual temperature data. In this study, we developed a resampling method for estimating the annual freezing and thawing index and compared the results with those produced by the existing methods. Daily temperature data with a 0.5° resolution over the Northern Hemisphere during 1901–2012 were used to calculate the freezing/thawing index, and then the monthly and annual temperature were calculated and three different approaches were used to estimate the daily temperature and the freezing/thawing index. When the monthly data were used, the resampling method produced the smallest relative error (RE) and mean bias error (MBE), and the largest correlation in estimating the two indices, compared to the two other methods. Although the annual temperature data usually underestimate the freezing/thawing index, the RE is still <5% over most of the high‐latitude regions. The results suggest that if the daily temperature can be reliably estimated using the resampling method, the thermal regimes of permafrost can be reliably estimated using modelled monthly temperature and/or reconstructed past monthly/annual temperature. These estimations can also be used to validate modelled paleo‐permafrost and its variations. Additionally, our results indicate that after the 1970s the annual freezing index (DDF) increased substantially, while the frost index (FI) decreased substantially.

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LGM permafrost distribution: how well can the latest PMIP multi-model ensembles perform reconstruction?

Cited by 42 publications

References 56 publications

Coupled Northern Hemisphere permafrost–ice-sheet evolution over the last glacial cycle

Coupled Northern Hemisphere permafrost–ice-sheet evolution over the last glacial cycle

Mid‐Holocene permafrost: Results from CMIP5 simulations

An improved method for calculating the freezing/thawing index using monthly and annual temperature data

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