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The Tibetan Plateau (TP), known as earth's "Third Pole," influences regional and even global weather and climate systems through its mechanical and thermal‐dynamical forcing. Near‐surface (2 m) air temperature (Ta) and surface (skin) temperature (Ts) are two crucial parameters of land–atmosphere interactions and climate change. Their difference (ΔT = Ts − Ta) determines the heating source over the TP that drives the Asian summer monsoon. This study focuses on climatology, inter‐annual variability, and long‐term trend of ΔT over the TP in the last four decades (1979–2018), based on four latest reanalysis datasets including ERA‐Interim, ERA5, MERRA2, and JRA55, along with observational data. We show that ΔT‐based different datasets display fairly different climatology in terms of seasonality, spatial distribution, and long‐term trend. ΔT exhibits a clear seasonality with negative value in winter and positive ones in summer despite different strengths and timings presented by the reanalyses. Along with global warming, all reanalyses except JRA55 exhibit obvious downwards trends of ΔT in a spatially non‐uniform way. The median ΔT among the four reanalyses features uniform decreases in all seasons, with the most distinct area on the northern TP, as well as the largest and least decreases in autumn and spring, respectively. Further analysis shows that the differences in ΔT are most likely associated with discrepancies in radiation forcing, snow cover, wind speed, and boundary layer height within the reanalyses. The present findings highlight the difficulty for the state‐of‐the‐art reanalyses to represent the climate change over the TP and point to possible factors behind the deficiencies identified. [ABSTRACT FROM AUTHOR]

Abstract Global warming has already had a significant impact on social ecosystems. The Tibetan Plateau (TP), which is characterized by a cryosphere, is also recognized to have a profound influence on regional and global climate systems, as well as the ecological economy. Therefore, research on the cryosphere is of significant importance. This paper comprehensively reviews the current status and recent changes of the cryosphere (e.g., glacier, snow cover, and frozen ground) in the TP from the perspectives of observations and simulations. Because of enhanced climate warming in the TP, a large portion of glaciers have experienced significant retreat since the 1960s, with obvious regional differences. The retreat is the smallest in the TP interior, and gradually increases towards the edges. Glacier simulations are comparatively few and still under development. Snow cover is a highly sensitive element of the cryosphere and decreases with large interdecadal variations from the 1960s to the 2010s in general. Simulations of snow cover mostly focus on the mutual feedback between the snow cover anomaly, climate and atmospheric circulation. In situ observations and simulations both indicate that the mean annual temperature of frozen ground increases, causing permafrost thaw and degradation and decreasing the seasonal freeze depth of seasonally frozen ground. Under future climate warming, the cryospheric elements in the TP will continue to diminish on the whole. Studies of climate and the cryosphere are ongoing. To date, the lack of observations is the biggest challenge on the TP, resulting in a divergence of cryosphere dynamics and its simulation being a bottleneck. To overcome these issues, a strategy that combines sets of in situ and remote sensing measurements and improved numerical models is of great importance for achieving breakthroughs with respect to research on the TP cryosphere and its interaction with climate. [ABSTRACT FROM AUTHOR]

[Display omitted] • CMIP6 models capture the dynamics of surface air temperature over the Tibetan Plateau. • Warming predicted to occur over the Tibetan Plateau. • The future warming rate is highly dependent on emission pathways. • The mean annual air temperature expected to break the 2 °C threshold in the next decade. With its amplification simultaneously emerging in cryospheric regions, especially in the Tibetan Plateau, global warming is undoubtedly occurring. In this study, we utilized 28 global climate models to assess model performance regarding surface air temperature over the Tibetan Plateau from 1961 to 2014, reported spatiotemporal variability in surface air temperature in the future under four scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5), and further quantified the timing of warming levels (1.5, 2, and 3 °C) in the region. The results show that the multimodel ensemble means depicted the spatiotemporal patterns of surface air temperature for the past decades well, although with differences across individual models. The projected surface air temperature, by 2099, would warm by 1.9, 3.2, 5.2, and 6.3 °C relative to the reference period (1981–2010), with increasing rates of 0.11, 0.31, 0.53, and 0.70 °C/decade under the SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios for the period 2015–2099, respectively. Compared with the preindustrial periods (1850–1900), the mean annual surface air temperature over the Tibetan Plateau has hit the 1.5 °C threshold and will break 2 °C in the next decade, but there is still a chance to limit the temperature below 3 °C in this century. Our study provides a new understanding of climate warming in high mountain areas and implies the urgent need to achieve carbon neutrality. [ABSTRACT FROM AUTHOR]

ABSTRACT On the basis of meteorological station records during 1961-2010, we investigate the variations of temperature and precipitation in the Qaidam Basin. Results show that climate warming is significant in the region of Qaidam Basin over the past 50 years, with an average warming rate of 0.53 °C 10a−1. The largest and smallest warming rate happened at Mangya station (0.89 °C 10a−1) and Lenghu station (0.24 °C 10a−1), respectively. Seasonal warming was greatest in winter at eight meteorological stations, ranging from 0.43 °C 10a−1 (Lenghu station) to 1.01 °C 10a−1 (Delingha station). Since 1961, the annual precipitation has increased with a rate of 7.38 mm 10a−1. Seasonal precipitation mainly increased in summer (4.02 mm 10a−1). The maximum precipitation increase occurred at Delingha station (25.09 mm 10a−1) and the minimum at Lenghu station (0.10 mm 10a−1). The elevation dependency of warming trends is unremarkable because most of the stations are located at lower altitudes. It is suggested that sunshine duration is related to the tendencies of temperature increase at different stations. Pollution emissions from industrial processes (i.e. brown clouds) and urbanization are the main factors contributing to the warming climate. Furthermore, the predominant weakening of zonal wind speed over the Tibetan Plateau resulted from the global warming also contributes to the climate warming in the Qaidam Basin. Consequently, the warming rate in the Qaidam Basin is much higher than in other regions over the Tibetan Plateau. The Qaidam Basin is thus considered to be the most susceptible region with the most significant warming in the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Abstract: A significant portion of the Tibetan Plateau is underlain by permafrost, and is highly sensitive to climate change. Observational data from recent Chinese investigations on permafrost degradation and its environmental effects in the Tibetan region indicate that a large portion of the Tibetan Plateau has experienced significant warming since the mid-1950s. The air temperature increase is most significant in the central, eastern, and northwestern parts of the Plateau. The warming trend in the cold season was greater than that in the warm season. The duration of seasonal ground freezing has shortened due to the air temperature increase in winter. Numerical simulations indicate that air temperature on the Plateau will continue to increase in the 21st century. Significant warming has resulted in extensive degradation of permafrost. Over the last 30years, a 25m increase in the lower altitudinal occurrences of permafrost has taken place in the north. In the south the increase is 50–80m over the past 20years. Active-layer thickness and mean annual ground temperature have increased by 0.15–0.50m during 1996–2001 and by 0.1–0.5°C during the last 30years on the Tibetan Plateau, respectively. Widespread permafrost degradation has already caused environmental deterioration. Extensive desertification processes are apparent in the eastern and western portions of the Tibetan Plateau, with the area occupied by desert increasing annually by about 1.8%. With rapid retreat and thinning of permafrost, large carbon pools sequestered in permafrost could be released to increase net sources of atmospheric carbon, creating a positive feedback and accelerated warming. Damage to human infrastructure is also caused by frost heave, thaw settlement, and thaw slumping in the permafrost-affected region. The impact of permafrost degradation on energy and water exchange processes between the ground and atmosphere require further examination. Large-scale intensive monitoring networks, remote sensing investigations, and models for frozen soil are needed to clarify regional details of climate change, permafrost degradation, and their environmental effects. [Copyright &y& Elsevier]

Annual streamflow of the Yellow River has decreased in recent years (1980 to 2000) because of climate change and human activity. This decrease affects the environment and the lives of the people in the drainage area. Tree ring width chronologies from six sites in the headwaters of the Yellow River were developed to provide estimates of past Yellow River streamflow in order to place the recent flow reduction in a long-term context. The ring width indices of the six local Juniperus przewalski chronologies correlate significantly with the observed streamflow of the Yellow River recorded at the Tangnaihai hydrological station. Principal components analysis shows that the first principal component (PC) of the tree ring indices explains 49% of the streamflow variance. On the basis of this result, Yellow River streamflow was reconstructed for the past 593 years. Several severe droughts and low-flow events are recognized in the decades 1920-1930, 1820-1830, 1700-1710, 1590-1600, and 1480-1490. The most severe droughts in 1480-1490 were also recorded in other studies on the Tibetan Plateau. Regional historical climate archives further support the validity of our streamflow reconstruction. The reconstructed increase in streamflow during much of the twentieth century also coincides with generally wetter conditions in the Tienshan and Qilianshan Mountains of China, as well as in northern Pakistan and Mongolia. After the 1980s, our reconstruction indicates a decreasing trend in streamflow, which is cause for concern. Presently, Yellow River streamflow is relatively low but not yet outside the range of streamflow fluctuations that occurred during the past six centuries. [ABSTRACT FROM AUTHOR]

We used the third generation Global Inventory Modeling and Mapping Studies normalized difference vegetation index (NDVI) and climate data (temperature and precipitation) to examine recent (1982–2012) spatial and temporal variations in vegetation, and relationships between climate and vegetation for both the growing period and for different seasons, on the Tibetan Plateau (TP). Across the whole plateau, trends calculated by linear regression showed that as temperature and precipitation increased, the growing season (May–September) NDVI values increased at rate of 0.002 decade −1 (p = 0.14) from 1982 to 2012. The ensemble empirical mode decomposition estimation method showed that the rates of increase in the NDVI gradually intensified until the end of the 1990s, and then decreased slightly in the following years. The autumn NDVI increased at a rate of 0.005 decade −1 (p = 0.04) and was a major contributor to the growing season NDVI. The NDVI and temperature were positively correlated at seasonal and monthly timescales during the growing season. The responses of vegetation growth to seasonal and monthly changes in precipitation, however, were complex. The NDVI trends showed obvious spatial heterogeneity and coincided well with regional and seasonal changes in climate. The growing season NDVI increased in 55% of the area of the TP. On a seasonal basis, the largest increase in the NDVI occurred in autumn and affected more than 61% of the TP, while the smallest increase in the NDVI occurred in spring, and affected over 41% of the area. Moreover, there were seasonal and spatial variations in the responses of different vegetation types to temperature and precipitation. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) is a vast elevated plateau in central Asia, and profoundly impacts regional weather and climate, and even global atmospheric circulation. Here, two frequently used ERA-Interim reanalyses with a spatial resolution of 1.5° × 1.5° (EIN15) and 0.75° × 0.75° (EIN75) are evaluated using a gridded observation dataset at 0.25° spatial resolution from the National Climate Center in China across the TP that covers the period 1979–2012. Climatological characteristics, mean monthly changes, and spatial–temporal trends are examined, with a focus on air temperature and precipitation. Topographic corrections for temperature in ERA-Interim are first conducted based on a vertical temperature lapse rate. The results show that EIN15 and EIN75 with topographic correction closely reproduce the spatial distribution and mean monthly change of temperature on the TP, notwithstanding some cold biases not seen in the observations. The two reanalysis datasets exhibit significant temperature increases over most of the TP, which is similar to the observations. However, the trends exhibit different spatial patterns for all seasons aside from summer, and have lower magnitudes than the observations. EIN15 and EIN75 also reproduce the broad spatial distribution of precipitation, but overestimate precipitation amounts, especially on the southern TP. They also capture some of the observed spatial patterns in the precipitation trend for the period 1979–2012, particularly in winter. Overall, the mean monthly change, mean annual, winter, and summer climatology, and their temporal trends of temperature reproduced by the ERA-Interim data are much better than those of precipitation. As a result of its higher resolution and more accurate topography, EIN75 generates a closer fit to the observed temperatures on the TP than EIN15, but there are no significant differences in precipitation between the two reanalysis datasets. Evaluation of these datasets would be very informative for further climate research and simulations on the TP. [ABSTRACT FROM AUTHOR]

Permafrost degradation poses serious threats to both natural and human systems through its influence on ecological–hydrological processes, infrastructure stability, and the climate system. The Arctic and the Third Pole (Tibetan Plateau, TP hereafter) are the two northern regions on Earth with the most extensive permafrost areas. However, there is a lack of systematic comparisons of permafrost characteristics and its climate and eco-environment between these two regions and their susceptibility to disturbances. This study provides a comprehensive review of the climate, ecosystem characteristics, ground temperature, permafrost extent, and active-layer thickness, as well as the past and future changes in permafrost in the Arctic and the TP. The potential consequences associated with permafrost degradation are also examined. Lastly, possible connections between the two regions through land-ocean–atmosphere interactions are explored. Both regions have experienced dramatic warming in recent decades, characterized by Arctic amplification and elevation-dependent warming on the TP. Permafrost temperatures have increased more rapidly in the Arctic than on the TP, and will likely be reinforced under a future high emission scenario. Near-surface permafrost extents are projected to shrink in both regions in the coming decades, with a more dramatic decline in the TP. The active layer on the TP is thicker and has substantially deepened, and is projected to thicken more than in the Arctic. Widespread permafrost degradation increases geohazard risk and has already wielded considerable effects on the human and natural systems. Permafrost changes have also exerted a pronounced impact on the climate system through changes in permafrost carbon and land–atmosphere interactions. Future research should involve comparative studies of permafrost dynamics in both regions that integrate long-term observations, high-resolution satellite measurements, and advanced Earth System models, with emphasis on linkages between the two regions. [ABSTRACT FROM AUTHOR]