Does elevation dependent warming exist in high mountain Asia?

Projection on elevation-dependent and latitude-dependent warming over Antarctica from CMIP6 under different socioeconomic scenarios

To explore the driving mechanisms of elevation-dependent warming (EDW) over the Tibetan Plateau (TP), the output from a suite of numerical experiments with different cumulus parameterization schemes (CPs) under the Coordinated Regional Climate Downscaling Experiments-East Asia (CORDEX-EA-II) project is examined. Results show that all experiments can broadly capture the observed temperature distributions over the TP with consistent cold biases, and the spread in temperature simulations commonly increases with elevation with the maximum located around 4000–5000 m. Such disagreements among the temperature simulations could to a large extent be explained by their spreads in the surface albedo feedback (SAF). All the experiments reproduce the observed EDW below 5000 m in winter but fail to capture the observed EDW above 4500 m in spring. Further analysis suggests that the simulated EDW during winter is mainly caused by the SAF, and the clear-sky downward longwave radiation (LWclr) plays a secondary role in shaping EDW. The models’ inability in simulating EDW during spring is closely related to the SAF and the surface cloud radiative forcing (CRFs). Furthermore, the magnitude and structure of the simulated EDW are sensitive to the choice of CPs. Different CPs generate diverse snow cover fractions, which can modulate the simulated SAF and its effect on EDW. Also, the CPs show great influence on the LWclr via altering the low-level air temperature. Additionally, the mechanism for different temperature changes among the experiments varies with altitudes during summer and autumn, as the diverse temperature changes appear to be caused by the LWclr for the low altitudes while by the SAF for the middle-high altitudes.

Warming in mountainous areas has obvious elevation dependence (warming rate increases with elevation), which deeply impacts runoff change in mountainous areas. This study analysed the influence of elevation-dependent warming on runoff in the headwater region of the Urumqi River Basin (URB) based on meteorological data, remote sensing images, and runoff data. Results indicated a significant warming rate in the URB from 1960 to 2019 (0.362 °C/decade; p < 0.01). The temperature increased with an obvious elevation-dependent warming in the URB, especially during winter. Glaciers sharply retreated in the headwater region of the URB under regional warming, and remote-based results showed that glacier areas decreased by 29.45 km2 (−57.81%) from the 1960s to 2017. The response of glacier mass balance and meltwater runoff to temperature change has a lag of 3 years in the headwater region of the URB. The elevation-dependent warming of temperature changes significantly impacted glacial meltwater runoff in the URB (R2 = 0.49). Rising temperatures altered the glacial meltwater runoff, and the maximum annual runoff of the Urumqi Glacier No. 1 meltwater runoff increased 78.6% in 1990–2017 compared to 1960–1990. During the period of 1960–1996, the total glacial meltwater runoff amounted to 26.9 × 108 m3, accounting for 33.4% of the total runoff during this period, whereas the total glacial meltwater runoff accounted for 51.1% of the total runoff in 1996–2006. Therefore, these results provide a useful reference for exploring runoff changes in mountainous watersheds in the context of elevation-dependent warming.

Under the Coordinated Regional Climate Downscaling Experiments‐East Asia (CORDEX‐EA‐II), the outputs from two regional climate models (RCMs) driven by four global climate models (GCMs) are used to investigate the characteristics and possible mechanisms of the projected elevation‐dependent warming (EDW) over the Tibetan Plateau (TP) under the Representative Concentration Pathway emission scenario 8.5 (RCP8.5). Results show that widespread warming over the TP is projected with considerable disagreements in warming intensity and the maximum warming center among RCMs. The largest spread in the surface air temperature (Tas) projections is found above 5,000 m, indicating that a large uncertainty exists over the higher elevations. A marked EDW signal over the TP is simulated under the RCP 8.5 by the multi‐RCM ensemble mean for all seasons, particularly in autumn. Based on the analysis of the surface energy budget, it is found that the surface albedo feedback (SAF) is the primary contributor to EDW and acts as the main source of uncertainty in EDW projections among RCMs. The downward longwave radiation (DLW) is found to be the dominant factor in regulating Tas change over the TP, and its contribution to EDW is model‐dependent. Furthermore, the structure and magnitude of projected EDW are sensitive to the RCM physics and driving GCM, as they can alter the projections of snow cover and albedo, which modulate the simulated SAF and its effect on EDW. Additionally, RegCM4 shows a higher sensitivity to the anthropogenic greenhouse forcing than WRF, evidenced by the larger temperature projections and stronger EDW signal in RegCM4.

Rethinking spatiotemporal variations in air temperature over the Qilian Mountains, Western China, from 1979 to 2018

The enhancement of warming rates with elevation, so-called elevation-dependent warming (EDW), is one of the regional, still not completely understood, expressions of global warming. Sentinels of climate and environmental changes, mountains have experienced more rapid and intense warming trends in the recent decades, leading to serious impacts on mountain ecosystems and downstream. In this paper we use a state-of-the-art Global Climate Model (EC-Earth) to investigate the impact of model spatial resolution on the representation of this phenomenon and to highlight possible differences in EDW and its causes in different mountain regions of the Northern Hemisphere. To this end we use EC-Earth climate simulations at five different spatial resolutions, from sim 125 to sim 16 km, to explore the existence and the driving mechanisms of EDW in the Colorado Rocky Mountains, the Greater Alpine Region and the Tibetan Plateau–Himalayas. Our results show that the more frequent EDW drivers in all regions and seasons are the changes in albedo and in downward thermal radiation and this is reflected in both daytime and nighttime warming. In the Tibetan Plateau-Himalayas and in the Greater Alpine Region, an additional driver is the change in specific humidity. We also find that, while generally the model shows no clear resolution dependence in its ability to simulate the existence of EDW in the different regions, specific EDW characteristics such as its intensity and the relative role of different driving mechanisms may be different in simulations performed at different spatial resolutions. Moreover, we find that the role of internal climate variability can be significant in modulating the EDW signal, as suggested by the spread found in the multi-member ensemble of the EC-Earth experiments which we use.

Accelerated glacier mass loss in the southeastern Tibetan Plateau since the 1970s

Elevation-dependent temperature change is a phenomenon found in mountain regions with complex terrain, mostly in the Himalayas and the high terrain of the Tibetan Plateau, where regions in high elevation feature high rates of warming than the region in lower elevation. This pattern referred to as elevation-dependent warming. However, does elevation-dependent warming exist in Eocene hothouse without Tibetan Plateau as well and lower altitude mountain ranges?The Eocene era is considered a replication of the future climate with high atmospheric carbon dioxide. We utilized CESM1.2 as part of the DeepMIP simulations to analyze elevation-dependent temperature change in different mountain ranges in the Eocene and explained the findings using a linear surface energy balance decomposition. The results feature a land-sea contrast with amplification over land and elevation-dependent temperature changes in all mountain ranges with distinct seasonality and pattern. The results suggest that radiative feedback processes have a strong contribution to elevation-dependent warming in the warming climate. Our modeling results provide relevant information for mountain climate change in a past hot climate. Further, the analysis opens new mystery and perspectives related to elevation-dependent warming. Keywords: Eocene, paleoclimate modeling, elevation-dependent warming, CO2 Related Publication:Kad P, Blau M T, Ha K-J, and Zhu J (2022) Elevation-dependent temperature response in early Eocene using paleoclimate model experiment. Environmental Research Letters, 17(11), 114038. (https://doi.org/10.1088/1748-9326/ac9c74)

Rapid elevation-dependent warming (EDW) in high mountain environments can accelerate the rate of change in permafrost and further induce the degradation of alpine tundra systems. However, how changes in area of alpine tundra response to EDW is difficult to be directly quantified at regional scales. Here, we project future changes in areal extent of the Koppen “alpine tundra” climate type in the Tibetan Plateau (TP), which is a potential indicator describing the climate conditions for the development of alpine tundra system, based on a suite of latest Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models under two emission scenarios (representative concentration pathways: RCP 4.5 and RCP 8.5). The results indicated that the Koppen “alpine tundra” climate type would gradually decrease in the TP for three future periods: 2011–2040, 2041–2070, and 2071–2100, especially under the RCP8.5 scenario. The decline in area of Koppen “alpine tundra” climate type mainly occurs above 2500 m above sea level (ASL) due to the EDW (> 10 °C) in the warmest months. The projected changes in area of “alpine tundra” climate type are overall consistent among different climate models, emission scenarios, and post-processing approaches (bias correction or not) used. The results obtained would thus deepen our understanding of future elevation-dependent warming and its potential influences on alpine tundra ecosystems in the Tibetan Plateau.

Abstract.With the exception of northern India, there are few, if any, consistent data records relating to avalanche activity in the high mountains of Asia. However, records do exist of avalanche fatalities in the region, contained in mountaineering expedition reports. In this paper, I review and analyze statistics of avalanche fatalities (both snow and ice) in the high mountains of Asia (Himalaya, Karakoram, Pamir, Hindu Kush, Tien Shan, Dazu Shan) from 1895 to 2014. The data are stratified according to accident cause, geographical region (Nepal-Tibet (Xizang), Pakistan, India, China, Central Asia), mountain range, personnel (hired or expedition members) and terrain. The character of the accidents is compared with data from North America and Europe. The data show that the important risk components are the temporal and spatial exposure probabilities. It is shown that human actions and decisions govern the pattern of fatal avalanches in the high mountains of Asia.

Abstract. Knowledge about the occurrence and characteristics of surge-type glaciers is crucial due to the impact of surging on glacier melt and glacier-related hazards. One of the super-clusters of surge-type glaciers is High Mountain Asia (HMA). However, no consistent region-wide inventory of surge-type glaciers in HMA exists. We present a regionally resolved inventory of surge-type glaciers based on their behaviour across High Mountain Asia between 2000 and 2018. We identify surge-type behaviour from surface velocity, elevation and feature change patterns using a multi-factor remote sensing approach that combines yearly ITS_LIVE velocity data, DEM differences and very-high-resolution imagery (Bing Maps, Google Earth). Out of the ≈95 000 glaciers in HMA, we identified 666 that show diagnostic surge-type glacier behaviour between 2000 and 2018, which are mainly found in the Karakoram (223) and the Pamir regions (223). The total area covered by the 666 surge-type glaciers represents 19.5 % of the glacierized area in Randolph Glacier Inventory (RGI) V6.0 polygons in HMA. Only 68 glaciers were already identified as “surge type” in the RGI V6.0. We further validate 107 glaciers previously labelled as “probably surge type” and newly identify 491 glaciers, not previously reported in other inventories covering HMA. We finally discuss the possibility of self-organized criticality in glacier surges. Across all regions of HMA, the surge-affected area within glacier complexes displays a significant power law dependency with glacier length.

High Mountain Asia (HMA) is one of the main distribution areas of surging glaciers in the world. The glacier change represented by the Karakoram anomaly has been a topic of wide concern. Surging glaciers not only reshape the peri-glacial landscape, but may also directly or indirectly lead to disasters. Therefore, it is of great importance to understand the distribution characteristics, periodic laws, and occurrence mechanisms of surging glaciers. Based on Landsat TM/ETM+/OLI remote sensing images from 1986–2021, a total of 244 surging glaciers in HMA were identified, covering an area of 10974.25 km2, accounting for 11.25 % of the total area of glaciers in HMA. The Karakoram Range and Pamirs are the main mountain/plateau where 185 surging glaciers are more highly concentrated. Three basins, including Amu Darya, Tarim and Indus, have 208 surging glaciers comprising 85.25 % of the total amount of surging glaciers in HMA, covering an area of 10096.89 km2. From 1986–2021, these surging glaciers advanced at least 2802 times, and exhibited different temporal and spatial trends. Obvious differences exist in the surge phase and the quiescent phase of glaciers in different regions of HMA. The surge phase of surging glaciers in the Karakoram Range and Pamirs is generally short, mostly between 2~6a, the quiescent phase is 5~19a, and the surging period is 9~24a. The mechanism of surging glaciers in HMA is more complex, which is different from Svalbard and Alaska glaciers.

Changes in terrestrial water storage (TWS) in High Mountain Asia (HMA) could have major societal impacts, as the region’s large reservoirs of glaciers, snow, and groundwater provide a freshwater source to more than one billion people. We seek to quantify and close the budget of secular changes in TWS over the span of the GRACE satellite mission (2003–2016). To assess the TWS trend budget we consider a new high-resolution mass trend product determined directly from GRACE L1B data, glacier mass balance derived from Digital Elevation Models (DEMs), groundwater variability determined from confined and unconfined well observations, and terrestrial water budget estimates from a suite of land surface model simulations with the NASA Land Information System (LIS). This effort is successful at closing the aggregated TWS trend budget over the entire HMA region, the glaciated portion of HMA, and the Indus and Ganges basins, where the full-region trends are primarily due to the glacier mass balance and groundwater signals. Additionally, we investigate the closure of TWS trends at individual 1-arc-degree mascons (area ≈12,000 km2); a significant improvement in spatial resolution over previous analyses of GRACE-derived trends. This mascon-level analysis reveals locations where the TWS trends are well-explained by the independent datasets, as well as regions where they are not; identifying specific geographic areas where additional data and model improvements are needed. The accurate characterization of total TWS trends and its components presented here is critical to understanding the complex dynamics of the region, and is a necessary step toward projecting future water mass changes in HMA.

High-Mountain Asia (HMA) is an important source of freshwater since it holds the largest reservoir of frozen water outside the polar regions. HMA feeds ten great rivers, ultimately supporting more than 2 billion people. However, the threat of accelerated glacier melt, which is a consequence of unprecedented global warming since the early 1950s, threatens water resources in the surrounding countries. Accurate predictions of the near-term temperature change and synergistic mass loss of glaciers are essential but challenging to implement because of the impacts of internal climate variability. Here, based on large ensembles of state-of-the-art decadal climate prediction experiments, we provide evidence that the internally generated surface air temperature variations in HMA can be predicted multiple years in advance, and the model initialization has robust added value to the decadal prediction skill. Real-time decadal forecasts suggest that the HMA will experience accelerated warming in 2025–2032, where the surface warming will increase by 0.98 °C (0.67 to 1.33 °C; 5 % to 95 % range) relative to the reference period 1991–2020, which is equivalent to 1.75 times the observed warming during 2016–2023. The decadal predictability originates from extratropical Pacific decadal variability modes, which modulate the convective heating in the tropical Pacific and influence HMA via the eastward-propagating atmospheric Kelvin waves. Accelerated warming in the coming decade will likely increase the shrinkage of the glacier volume over the HMA by 1.4 %. This change poses unprecedented challenges, including potential water scarcity, ecosystem disruption, and increased risk of natural disasters, to HMA and surrounding regions.

Over the past century, global irrigation extent has expanded nearly fivefold, increasing from approximately 63Mha in the early 1900s to over 306Mha today. This growth has been particularly pronounced in Asia, which accounts for roughly 85% of current global irrigation withdrawals. Irrigation, as one of the most impactful land management practices, substantially influences regional climate by altering precipitation patterns and cooling surface air temperatures. These meteorological changes raise important questions about how irrigation-driven weather modifications might affect glaciers in High Mountain Asia (HMA). This study investigates the impact of irrigation expansion on glaciers in HMA using simulations from the Irrigation Model Intercomparison Project (IRRMIP). IRRMIP provides historical climate simulations (1901-2014) under two contrasting scenarios: (1) the Irr-scenario, representing real-world irrigation trends, and (2) the NoIrr-scenario, modeling a world with irrigation extent fixed at early 20th-century levels. These scenarios are then used as inputs for the Open Global Glacier Model (OGGM) to assess the effects of irrigation expansion-induced climate changes on glaciers. Our results reveal that irrigation expansion had an important impact on glacier changes in HMA. Without irrigation expansion, glaciers would have lost considerably greater volume loss over the 1985-2014 period compared to the real-world case with irrigation expansion. This outcome discovers the buffering effect of irrigation on glaciers in HMA, partially offsetting climate-induced glacier loss and underscores the interconnection between human land management and cryospheric systems.