Recent permafrost warming on the Qinghai‐Tibetan Plateau

Wu, Qingbai; Zhang, Tingjun

doi:10.1029/2007jd009539

Cited by 347 publications

(261 citation statements)

References 49 publications

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“…However, permafrost bodies have a long response time to atmospheric conditions (Riseborough, 2007;Romanovsky et al, 2010;Smith et al, 2010). The increasing rates of ground temperature were much lower in the TP than that in the circumpolar regions and much lower for the warm permafrost (Wu and Zhang, 2008;Smith et al, 2005;Zhao et al, 2010), which is mostly distributed near the permafrost boundaries. Moreover, the degradation of permafrost in these regions was characterized by a deepening of the active layer, rather than the disappearance of permafrost.…”

Section: Discussionmentioning

confidence: 99%

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A new map of permafrost distribution on the Tibetan Plateau

et al. 2017

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Abstract. The Tibetan Plateau (TP) has the largest areas of permafrost terrain in the mid-and low-latitude regions of the world. Some permafrost distribution maps have been compiled but, due to limited data sources, ambiguous criteria, inadequate validation, and deficiency of high-quality spatial data sets, there is high uncertainty in the mapping of the permafrost distribution on the TP. We generated a new permafrost map based on freezing and thawing indices from modified Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperatures (LSTs) and validated this map using various ground-based data sets. The soil thermal properties of five soil types across the TP were estimated according to an empirical equation and soil properties (moisture content and bulk density). The temperature at the top of permafrost (TTOP) model was applied to simulate the permafrost distribution. Permafrost, seasonally frozen ground, and unfrozen ground covered areas of 1.06 × 10 6 km 2 (0.97-1.15 × 10 6 km 2 , 90 % confidence interval) (40 %), 1.46 × 10 6 (56 %), and 0.03 × 10 6 km 2 (1 %), respectively, excluding glaciers and lakes. Ground-based observations of the permafrost distribution across the five investigated regions (IRs, located in the transition zones of the permafrost and seasonally frozen ground) and three highway transects (across the entire permafrost regions from north to south) were used to validate the model. Validation results showed that the kappa coefficient varied from 0.38 to 0.78 with a mean of 0.57 for the five IRs and 0.62 to 0.74 with a mean of 0.68 within the three transects. Compared with earlier studies, the TTOP modelling results show greater accuracy. The results provide more detailed information on the permafrost distribution and basic data for use in future research on the Tibetan Plateau permafrost.

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Section: Discussionmentioning

confidence: 99%

“…The ground temperatures of permafrost on the TP have increased during the past several decades (Wu and Liu, 2004;Wu and Zhang, 2008;Zhao et al, 2010). This means a disequilibrium of permafrost under ongoing climate warming, and thereby any map based on a contemporary climate forcing is likely to underestimate the extent of permafrost.…”

Section: Discussionmentioning

confidence: 99%

A new map of permafrost distribution on the Tibetan Plateau

et al. 2017

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“…Knowledge of ST trends in long time series through the soil profile is deemed as an effective approach to reflect the degree of climate change accurately (Yang et al 2010a;Yang et al 2010b). Recently, there have been numerous reports of ST variation associated with the climate change in various parts of the world, such as Alaska and Siberia (Oelke and Zhang 2004), Turkey (Yeşilırmak 2014), Canada (Qian et al 2011), Russia (Zhang et al 2001), and China (Wang et al 2009;Wang et al 2014b;Wu and Zhang 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Owing to the cold and semi-arid climate features, one classical terrain features of the TP is the widespread permafrost or the seasonal frozen ground. The permafrost, covering an area of 1.73 × 10 6 km 2 (Yang et al 2010a), occupies greater than two thirds area of the TP, while areal extent of seasonally frozen ground (including the active layer over permafrost) covers, on average, approximately all of the TP (Wu and Zhang 2008).…”

Section: Introductionmentioning

confidence: 99%

Observed soil temperature trends associated with climate change in the Tibetan Plateau, 1960–2014

Fang

Luo

Lyu

2018

Theor Appl Climatol

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Soil temperature, an important indicator of climate change, has rarely explored due to scarce observations, especially in the Tibetan Plateau (TP) area. In this study, changes observed in five meteorological variables obtained from the TP between 1960 and 2014 were investigated using two non-parametric methods, the modified Mann-Kendall test and Sen's slope estimator method. Analysis of annual series from 1960 to 2014 has shown that surface (0 cm), shallow (5-20 cm), deep (40-320 cm) soil temperatures (ST), mean air temperature (AT), and precipitation (P) increased with rates of 0.47°C/decade, 0.36°C/decade, 0.36°C/decade, 0.35°C/decade, and 7.36 mm/decade, respectively, while maximum frozen soil depth (MFD) as well as snow cover depth (MSD) decreased with rates of 5.58 and 0.07 cm/decade. Trends were significant at 99 or 95% confidence level for the variables, with the exception of P and MSD. More impressive rate of the ST at each level than the AT indicates the clear response of soil to climate warming on a regional scale. Monthly changes observed in surface ST in the past decades were consistent with those of AT, indicating a central place of AT in the soil warming. In addition, with the exception of MFD, regional scale increasing trend of P as well as the decreasing MSD also shed light on the mechanisms driving soil trends. Significant negative-dominated correlation coefficients (α = 0.05) between ST and MSD indicate the decreasing MSD trends in TP were attributable to increasing ST, especially in surface layer. Owing to the frozen ground, the relationship between ST and P is complicated in the area. Higher P also induced higher ST, while the inhibition of freeze and thaw process on the ST in summer. With the increasing AT, P accompanied with the decreasing MFD, MSD should be the major factors induced the conspicuous soil warming of the TP in the past decades.

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“…Due to global climate warming, significant efforts have been devoted to permafrost research, such as permafrost variations on the hemispheric-scale permafrost temperature changes (Wu and Zhang, 2008;Guglielmin and Cannone, 2012;Streletskiy et al, 2014;Wu et al, 2015), permafrost degradation (Jorgenson et al, 2006;Ravanel et al, 2010;Sannel and Kuhry, 2011;Streletskiy et al, 2015a;Park et al, 2016), hydrological processes in permafrost regions Wang et al, 2009;Park et al, 2013;Streletskiy et al, 2015b;Ford and Frauenfeld, 2016), feedbacks to climate change (Schuur et al, 2008;Park et al, 2015;Abbott et al, 2016), and other aspects. The increasing thickness of the active layer has been indicated by many observations in permafrost regions at high latitudes and altitudes (Brown et al, 2000;Frauenfeld et al, 2004;Zhang et al, 2005;Fyodorov-Davydov et al, 2008;Wu et al, 2010;Zhao et al, 2010;Callaghan et al, 2011;Liu et al, 2014a, b;Stocker et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Response of seasonal soil freeze depth to climate change across China

et al. 2017

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Abstract. The response of seasonal soil freeze depth to climate change has repercussions for the surface energy and water balance, ecosystems, the carbon cycle, and soil nutrient exchange. Despite its importance, the response of soil freeze depth to climate change is largely unknown. This study employs the Stefan solution and observations from 845 meteorological stations to investigate the response of variations in soil freeze depth to climate change across China. Observations include daily air temperatures, daily soil temperatures at various depths, mean monthly gridded air temperatures, and the normalized difference vegetation index. Results show that soil freeze depth decreased significantly at a rate of −0.18 ± 0.03 cm yr −1 , resulting in a net decrease of 8.05 ± 1.5 cm over 1967-2012 across China. On the regional scale, soil freeze depth decreases varied between 0.0 and 0.4 cm yr −1 in most parts of China during 1950-2009. By investigating potential climatic and environmental driving factors of soil freeze depth variability, we find that mean annual air temperature and ground surface temperature, air thawing index, ground surface thawing index, and vegetation growth are all negatively associated with soil freeze depth. Changes in snow depth are not correlated with soil freeze depth. Air and ground surface freezing indices are positively correlated with soil freeze depth. Comparing these potential driving factors of soil freeze depth, we find that freezing index and vegetation growth are more strongly correlated with soil freeze depth, while snow depth is not significant. We conclude that air temperature increases are responsible for the decrease in seasonal freeze depth. These results are important for understanding the soil freeze-thaw dynamics and the impacts of soil freeze depth on ecosystem and hydrological process.

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Recent permafrost warming on the Qinghai‐Tibetan Plateau

Cited by 347 publications

References 49 publications

A new map of permafrost distribution on the Tibetan Plateau

A new map of permafrost distribution on the Tibetan Plateau

Observed soil temperature trends associated with climate change in the Tibetan Plateau, 1960–2014

Response of seasonal soil freeze depth to climate change across China

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