Analysis of Permafrost Thermal Dynamics and Response to Climate Change in the CMIP5 Earth System Models

Koven, Charles D.; Riley, William J.; Stern, Alex

doi:10.1175/jcli-d-12-00228.1

Cited by 388 publications

(462 citation statements)

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“…For strong carbon loss, deeper permafrost carbon (∼10 m) is much more vulnerable to decomposition on warming. Because the processes controlling the rate and extent of deep permafrost thaw are highly uncertain, models cannot project the timing or magnitude of permafrost carbon release accurately (19,25,26). Therefore, CO 2 observing strategies designed to monitor changes in Arctic respiration patterns will be needed to avoid the risk of emerging permafrost carbon sources going undetected.…”

Section: Resultsmentioning

confidence: 99%

Detecting regional patterns of changing CO ₂ flux in Alaska

Parazoo

Commane

Wofsy

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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With rapid changes in climate and the seasonal amplitude of carbon dioxide (CO 2 ) in the Arctic, it is critical that we detect and quantify the underlying processes controlling the changing amplitude of CO 2 to better predict carbon cycle feedbacks in the Arctic climate system. We use satellite and airborne observations of atmospheric CO 2 with climatically forced CO 2 flux simulations to assess the detectability of Alaskan carbon cycle signals as future warming evolves. We find that current satellite remote sensing technologies can detect changing uptake accurately during the growing season but lack sufficient cold season coverage and near-surface sensitivity to constrain annual carbon balance changes at regional scale. Airborne strategies that target regular vertical profile measurements within continental interiors are more sensitive to regional flux deeper into the cold season but currently lack sufficient spatial coverage throughout the entire cold season. Thus, the current CO 2 observing network is unlikely to detect potentially large CO 2 sources associated with deep permafrost thaw and cold season respiration expected over the next 50 y. Although continuity of current observations is vital, strategies and technologies focused on cold season measurements (active remote sensing, aircraft, and tall towers) and systematic sampling of vertical profiles across continental interiors over the full annual cycle are required to detect the onset of carbon release from thawing permafrost.carbon cycle | permafrost thaw | climate | Earth system models | remote sensing T he future trajectory of carbon balance in the Arctic-Boreal Zone (ABZ) is of global importance because of the vast quantities of carbon sequestered in permafrost soils (1). Climate warming threatens to increase permafrost thaw and release soil carbon back to the atmosphere as a positive feedback promoting additional warming (2). It is unclear whether the observed intensification of the northern high-latitude carbon cycle is dominated by plant productivity or microbial decomposition, both of which seem to be increasing (3-6). Although warming temperatures and C/N fertilization promote greening and higher summer productivity during the short, intense growing season, these same factors also drive increased emissions during the long cold season (3-5).Detecting changes in ABZ carbon balance requires sustained observations over the full annual cycle. In the last decade, researchers have recognized the importance of year-round landatmosphere CO 2 flux observations (3-5). Synthesis studies of these data show that increasing growing season uptake has been offset by stronger winter respiration. Measurements of atmospheric CO 2 collected from in situ and remote sensing instruments provide spatially and temporally integrated constraints of net CO 2 exchange on regional to pan-Arctic scales. In situ observations have been limited primarily to a small network of surface towers and infrequent, short duration airborne campaigns designed primarily to detect the pan-Ar...

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Section: Resultsmentioning

confidence: 99%

Detecting regional patterns of changing CO ₂ flux in Alaska

Parazoo

Commane

Wofsy

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Comparing this to performance of other models (Levavasseur et al, 2011), the PI(eq) total permafrost area is closer to Zhang et al (2000) estimates, but it must be kept in mind that for CLIMBER-2P the area was tuned to be in agreement with a mean estimate from Zhang et al (2000). The PI(tr) total permafrost area is higher by around 4 × 10 6 km 2 compared to the PI(eq).…”

Section: Permafrost Areal Coverage and Spatial Distributionmentioning

confidence: 62%

“…These settings were identified by adjusting the sigmoid function to obtain total permafrost area values at the PI(eq) simulation similar to the Zhang et al (2000) areal estimates of permafrost and to maximise the difference in area between the PI(eq) and LGM(eq) simulations permafrost extent. More complex models underestimate permafrost extent at LGM (Levavasseur et al, 2011;Saito et al, 2013) quite significantly, and so by maximising the difference between PI and LGM permafrost, we reduce the underestimate as far as possible for LGM permafrost extent. Figure 11.…”

Section: Permafrost Extent Tuningmentioning

confidence: 99%

“…Their conclusions are that "current models are insufficiently equipped to quantify the carbon release at rapid thaw of ice-rich permafrost", which within a model would require accurate representation of local topography and hydrology as well as a priori knowledge of the ice content in the soils. Koven et al (2013) further highlighted the importance of soil depths and of soil and snow dynamics for the accuracy of permafrost extent in CMIP (coupled model intercomparison project) models. The high computing power requirements of physical models at grid sizes where output could be an acceptable confidence level makes these kinds of models currently unsuitable for long-timescale dynamically coupled modelling studies.…”

Section: Introductionmentioning

confidence: 99%

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A simplified permafrost-carbon model for long-term climate studies with the CLIMBER-2 coupled earth system model

et al. 2014

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Abstract. We present the development and validation of a simplified permafrost-carbon mechanism for use with the land surface scheme operating in the CLIMBER-2 earth system model. The simplified model estimates the permafrost fraction of each grid cell according to the balance between modelled cold (below 0 • C) and warm (above 0 • C) days in a year. Areas diagnosed as permafrost are assigned a reduction in soil decomposition rate, thus creating a slow accumulating soil carbon pool. In warming climates, permafrost extent reduces and soil decomposition rates increase, resulting in soil carbon release to the atmosphere. Four accumulation/decomposition rate settings are retained for experiments within the CLIMBER-2(P) model, which are tuned to agree with estimates of total land carbon stocks today and at the last glacial maximum. The distribution of this permafrost-carbon pool is in broad agreement with measurement data for soil carbon content. The level of complexity of the permafrostcarbon model is comparable to other components in the CLIMBER-2 earth system model.

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“…Brief information about the eight climate models is provided in Table 1, and additional details regarding the CMIP5 simulation are available in Taylor et al (2012). These data have been widely used to diagnose changes in permafrost in response to climate change in the future (Koven et al 2013;Slater and Lawrence 2013).…”

Section: Datamentioning

confidence: 99%

Permafrost Thaw and Associated Settlement Hazard Onset Timing over the Qinghai-Tibet Engineering Corridor

Guo

Sun

2015

Int J Disaster Risk Sci

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In permafrost areas, the timing of thermal surface settlement hazard onset is of great importance for the construction and maintenance of engineering facilities. Future permafrost thaw and the associated thermal settlement hazard onset timing in the Qinghai-Tibet engineering corridor (QTEC) were analyzed using high-resolution soil temperature data from the Community Land Model version 4 in combination with multiple model and scenario soil temperature data from the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Compared to the standard frozen ground map for the Tibetan Plateau and ERAInterim data, a multimodel ensemble reproduces the extent of permafrost and soil temperature change in the QTEC at a 1 m depth from 1986-2005. Soil temperature and active layer thickness increase markedly during 2006-2099 using CMIP5 scenarios. By 2099, the ensemble mean soil temperature at 15 m depth will increase between 1.0 and 3.6°C in the QTEC. Using crushed-rock revetments can delay the onset of thermal settlement hazard for colder permafrost areas by approximately 17 years in the worst case scenario of RCP8.5. Nearly one-third of the area of the QTEC exhibits settlement hazard as early as 2050, and half of this one-third of the area is traversed by the QinghaiTibet highway/railway, a situation that requires more planning and remedial attention. Simulated onsets of thermal settlement hazard correspond well to the observed soil temperature at 15 m depth for seven grid areas in the QETC, which to some extent indicates that these timing estimates are reasonable. This study suggests that climate model-based timing estimation of thermal settlement hazard onset is a valuable method, and that the results are worthy of consideration in engineering design and evaluation.

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Analysis of Permafrost Thermal Dynamics and Response to Climate Change in the CMIP5 Earth System Models

Cited by 388 publications

References 43 publications

Detecting regional patterns of changing CO ₂ flux in Alaska

Detecting regional patterns of changing CO ₂ flux in Alaska

A simplified permafrost-carbon model for long-term climate studies with the CLIMBER-2 coupled earth system model

Permafrost Thaw and Associated Settlement Hazard Onset Timing over the Qinghai-Tibet Engineering Corridor

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Analysis of Permafrost Thermal Dynamics and Response to Climate Change in the CMIP5 Earth System Models

Cited by 388 publications

References 43 publications

Detecting regional patterns of changing CO 2 flux in Alaska

Detecting regional patterns of changing CO 2 flux in Alaska

A simplified permafrost-carbon model for long-term climate studies with the CLIMBER-2 coupled earth system model

Permafrost Thaw and Associated Settlement Hazard Onset Timing over the Qinghai-Tibet Engineering Corridor

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Detecting regional patterns of changing CO ₂ flux in Alaska

Detecting regional patterns of changing CO ₂ flux in Alaska