Glaciers In Asia Research Articles

Seasonal Cycles of High Mountain Asia Glacier Surface Elevation Detected by ICESat‐2

AbstractHigh Mountain Asia (HMA) glaciers are a key component of mountain hydrology and their seasonal ablation contributes significantly to the annual runoff of several large river systems that protect large populations from water stress. However, the seasonal cycle of glacial change remains unclear. Recent NASA's Ice, Cloud, and Land Elevation Satellite (ICESat‐2) provides an opportunity to survey changes in the glacier surface elevation in unprecedented detail. Here, we used a new approach—which is based on a developed elevation bin cluster with a sliding filter and an iterative recovery method—to obtain the complete seasonal cycle of glacier thickness changes in HMA. We generally identified three types of glaciers: (a) glaciers in the westerly dominant area (WDA) (b) glaciers in the Indian monsoon area (IMA), and (c) glaciers in the transition area (TA). The peak thickness values for the IMA, WDA, and TA glaciers occur in February, May, and June, respectively. Most glaciers in WDA and IMA show a strong seasonal cycle with variations of more than 2 m, while the TA glaciers are mainly characterized by weak changes of up to 1 m. Overall, our results show that the glaciers can provide 67–138 Gt of meltwater per year to downstream. These results provide crucial information for the calibration of models that project glacier response to climate change and simulate the downstream water availability. Our methodology facilitates the application of ICESat‐2 to seasonal tracking of glacier variability in global alpine areas.

РЕКОНСТРУКЦИЯ БАЛАНСА МАССЫ ЛЕДНИКА САРЫ-ТОР ПО МЕТЕОРОЛОГИЧЕСКИМ ДАННЫМ

Mass balance bn is the most important indicator of a glacier evolution. However, after the decay of the USSR direct measurements of bn performed in 1985–1989 in the Inner Tien Shan, including the Sary-Tor Glacier in Ak-Shiyrak Massif, had been desisted. As a result the available series of the data were limited 1989. Measurements in this area were renewed only in 2015. This paper is devoted to restoring the continuity of the mass-balance series over the period of the gap in measurements and extending this series down to 1929, i.e. to the beginning of regular meteorological observations on the reference HMS Tien Shan (3660 m a.m.s.l.). Accumulation was reconstructed using a linear relationship of bn with the air temperature and precipitation sum. Reconstruction of ablation was based on its cubic relationship with the temperature (modified Krenke– Khodakov formula) or on two-parameter linear approximation using the air temperature and wind velocity. Thereby, the decade of direct instrumental measurements (1984/85–1988/89 and 2014/15–2018/19) resulted in deriving and analyzing continuous 90-year-long series of annual values of bn and its constituents, analytical type of referent glacio-meteorological equations being assumed unchanged in time. Reconstruction for the Sary-Tor Glacier reveals a dominant trend towards the mass loss with rare and short-time episodes of retarding the negative tendencies. The comparison made with the long series of mass balance of other glaciers in Asia indicates a certain degree of synchronicity, which is slightly disturbed in recent years: the degradation of Sary Tor Glacier tends to progress more intensively. Conclusions about its evolution are particularly relevant in connection with the assumption about the impact of the Kyrgyz-Canadian gold mining company «Kumtor Gold Company» on local ecosystems against the background of its interest in expanding the mining zone to the bowels of the Earth under the tongue of this glaciological object.

A Systematic, Regional Assessment of High Mountain Asia Glacier Mass Balance

High-mountain Asia (HMA) constitutes the largest glacierized region outside of the Earth's polar regions. Although available observations are limited, long-term records indicate sustained HMA glacier mass loss since ~1850, with accelerated loss in recent decades. Recent satellite data capture the spatial variability of this mass loss, but spatial resolution is coarse and some estimates for regional and HMA-wide mass loss disagree. To address these issues, we generated 5797 high-resolution digital elevation models (DEMs) from available sub-meter commercial stereo imagery (DigitalGlobe WorldView-1/2/3 and GeoEye-1) acquired over HMA glaciers from 2007–2018 (primarily 2013–2017). We also reprocessed 28278 ASTER DEMs over HMA from 2000–2018. We combined these observations to generate robust elevation change trend maps and geodetic mass balance estimates for 99% of HMA glaciers between 2000 and 2018. We estimate total HMA glacier mass change of -19.0±2.5 Gt yr-1 (-0.19±0.03 m w.e. yr-1). We document the spatial pattern of HMA glacier mass change with unprecedented detail, and present aggregated estimates for HMA glacierized sub-regions and hydrologic basins. Our results offer improved estimates for the HMA contribution to global sea level rise in recent decades with total cumulative sea-level rise contribution of ~0.7 mm from exorheic basins between 2000 and 2018. We estimate that the range of excess glacier meltwater runoff due to negative glacier mass balance in each basin constitutes ~12-53% of the total basin-specific glacier meltwater runoff. These results can be used for calibration and validation of glacier mass balance models, satellite gravimetry observations, and hydrologic models needed for present and future water resource management.

Dissolved Iron Supply from Asian Glaciers: Local Controls and a Regional Perspective

AbstractIce sheets have been shown to deliver large amounts of labile iron (Fe) to aquatic ecosystems; however, the role of glaciers distinct from ice sheets in supplying labile Fe to downstream ecosystems is less well understood despite their rapid volume loss globally. Direct and continuous measurements of Fe from glaciers throughout an entire melt season are very limited to date. Here we present extensive seasonal data on 0.45‐μm‐filtered Fe (dFe) from three glaciers in Asia. Concentrations of dFe are negatively correlated with glacier discharge, and dFe yields are closely related to specific discharge. Based on our study and previously published dFe data, we estimate the release of dFe from Asian glaciers to be 23.8±14.1 Gg/a. We further compile a global data set of dFe from more than 12 glaciers, which, when combined with data on glacier discharge, suggest that the release of dFe from glaciers globally is on the order of 185±172 Gg/a. This finding suggests that glaciers may provide a substantial, but largely unrecognized source of potentially labile Fe, and may become increasingly important for the Fe biogeochemical cycle in a warming climate.

Quantifying the range of future glacier mass change projections caused by differences among observed past-climate datasets

Observed past climate data used as input in glacier models are expected to differ among datasets, particularly those for precipitation at high elevations. Differences among observed past climate datasets have not yet been described as a cause of uncertainty in projections of future changes in glacier mass, although uncertainty caused by varying future climate projections among general circulation models (GCMs) has often been discussed. Differences among observed past climate datasets are expected to propagate as uncertainty in future changes in glacier mass due to bias correction of GCMs and calibration of glacier models. We project ensemble future changes in the mass of glaciers in Asia through the year 2100 using a glacier model. A set of 18 combinations of inputs, including two observed past air temperature datasets, three observed past precipitation datasets, and future air temperature and precipitation projections from three GCMs were used. The uncertainty in projected changes in glacier mass was partitioned into three distinct sources: GCM uncertainty, observed past air temperature uncertainty, and observed past-precipitation uncertainty. Our findings indicate that, in addition to the differences in climate projections among GCMs, differences among observed past climate datasets propagate fractional uncertainties of about 15% into projected changes in glacier mass. The fractional uncertainty associated with observed past precipitation was 33–50% that of the observed air temperature. Differences in observed past air temperatures and precipitation did not propagate equally into the ultimate uncertainty of glacier mass projection when ablation was dominant.

Author Correction: A spatially resolved estimate of High Mountain Asia glacier mass balances from 2000 to 2016

In the version of this Article originally published, the symbols for ‘greater than’ and ‘less than or equal to’ were inverted in the equation that defines σΔz. The original (1) and corrected (2) versions of the equation are shown below. This error did not affect the calculation of the uncertainties. In addition, erroneous values that were a remnant of an earlier version of the authors’ work and higher than the final values calculated were reported for the uncertainties on ASTER estimates in Supplementary Table 4. Table 1 below shows the corrected values in bold font. These errors have now been corrected in the online versions of the Article.

Asia's glacier changes

Mass changes in High Mountain Asia's glaciers have been under dispute for almost a decade. An analysis of satellite data archives provides an observation-based mass budget for every single glacier in the region.

Cryospheric science: Asia's glacier changes

Cryospheric science: Asia's glacier changes

A spatially resolved estimate of High Mountain Asia glacier mass balances, 2000-2016.

High Mountain Asia hosts the largest glacier concentration outside the polar regions. These glaciers are important contributors to streamflow in one of the most populated areas of the world. Past studies have used methods that can only provide regionally-averaged glacier mass balances to assess the High Mountain Asia glacier contribution to rivers and sea level rise. Here we compute the mass balance for about 92 % of the glacierized area of High Mountain Asia using time series of digital elevation models derived from satellite stereo-imagery. We calculate an average region-wide mass balance of -16.3 ± 3.5 Gt yr-1 (-0.18 ± 0.04 m w.e. yr-1) between 2000 and 2016, which is less negative than most previous estimates. Region-wide mass balances vary from -4.0 ± 1.5 Gt yr-1 (-0.62 ± 0.23 m w.e. yr-1) in Nyainqentanglha to +1.4 ± 0.8 Gt yr-1 (+0.14 ± 0.08 m w.e. yr-1) in Kunlun, with large intra-regional variability of individual glacier mass balances (standard deviation within a region ˜0.20 m w.e. yr-1). Specifically, our results shed light on the Nyainqentanglha and Pamir glacier mass changes, for which contradictory estimates exist in the literature. They provide crucial information for the calibration of the models used for projections of future glacier response to climatic changes, models that presently do not capture the pattern, magnitude and intra-regional variability of glacier changes in High Mountain Asia.

The High Mountain Asia glacier contribution to sea-level rise from 2000 to 2050

AbstractWe estimate all the individual glacier area and volume changes in High Mountain Asia (HMA) by 2050 based on Randolph Glacier Inventory (RGI) version 4.0, using different methods of assessing sensitivity to summer temperatures driven by a regional climate model and the IPCC A1B radiative forcing scenario. A large range of sea-level rise variation comes from varying equilibrium-line altitude (ELA) sensitivity to summer temperatures. This sensitivity and also the glacier mass-balance gradients with elevation have the largest coefficients of variability (amounting to ~50%) among factors examined. Prescribing ELA sensitivities from energy-balance models produces the highest sea-level rise (9.2 mm, or 0.76% of glacier volume a–1), while the ELA sensitivities estimated from summer temperatures at Chinese meteorological stations and also from 1°x1° gridded temperatures in the Berkeley Earth database produce 3.6 and 3.8 mm, respectively. Different choices of the initial ELA or summer precipitation lead to 15% uncertainties in modelled glacier volume loss. RGI version 4.0 produces 20% lower sea-level rise than version 2.0. More surface mass-balance observations, meteorological data from the glaciated areas, and detailed satellite altimetry data can provide better estimates of sea-level rise in the future.

Glacier fluctuation in northern and High Asia: historical and methods perspective

Glaciers in Asia occupy nowadays much smaller extents than those of the Pleistocene but they still play an important role in alpine ecosystems (e.g., Shahgedanova 2002). Glaciers also pose hazards to society and infrastructure, with avalanches and glacial lake outburst floods being the most destructive of glacier-related natural events (Richardson and Reynolds 2000; Janský et al. 2010; Nie et al. 2013; Wang and Zhang 2014). Since the end of the Little Ice Age (LIA), glaciers have been retreating almost everywhere around the world, and this process has dramatically accelerated during the recent decades (Fig. 1; WGMS 2013). However, individual glaciers are behaving differently and some have advanced while most have been in retreat (IPCC 2013; Yao et al. 2012). Mountain glaciers are sensitive indicators of climate change (e.g., Dyurgerov and Meier 2000; Haeberli et al. 2004) and to fully understand the connection between changing climate and glacier fluctuations, all the variables of the glacier mass balance need to be assessed at the local and regional scale (Dowdeswell et al. 1997; Oerlemans 2005). One of the regions where information about glacier changes is still scarce is northern and High Asia (Fig. 1), largely because glaciers of the region are located relatively far from human settlements and some have only been found after the 1940s. For example, Ivanov et al. (2015) have provided the first inventory of glaciers in the Barguzinsky Ridge east of Lake Baikal, Russia, in this issue. At the same time, continental glaciers of northern and High Asia are located far from the main sources of moisture and are thus sensitive to climate change (Fujita 2008; Kaser et al. 2010). In this issue, we have collected information about glaciers situated along a southwestnortheast transect from 77 E, 32 N (the Western Himalaya, India) to 128 E 65 N (the Orulgan Range, Russia; Fig. 2) and fed from different sources of moisture (the North Atlantic, the Arctic and the Indo-Pacific air masses). Because glaciers in our focus area belong to different climate systems, their systematic study across the whole region has the potential not only to assess the climate change at local and regional scales but also to reveal climate change patterns at a larger, continental scale. The papers of this issue cover a variety of glacier-related topics (methods studies, glacier inventories, current glacier dynamics, and paleo-reconstructions), and are based on a range of data, such as satellite imagery, synoptic maps, biogeochemical proxies from proglacial lake bottom sediments and meltwater streams, pollen and oxygen isotope records from snow-ice cores, and high-resolution seismic reflection data.

アジア，アラスカ，グリーンランドの氷河上クリオコナイトのSr, Nd同位体比

アジア，アラスカ，グリーンランドの氷河上クリオコナイトのSr, Nd同位体比

The Northeast Asia mountain glaciers in the near future by AOGCM scenarios

Abstract. We studied contrasting glacier systems in continental (Orulgan, Suntar-Khayata and Chersky) mountain ranges, located in the region of the lowest temperatures in the Northern Hemisphere at the boundary of Atlantic and Pacific influences – and maritime ones (Kamchatka Peninsula) – under Pacific influence. Our purpose is to present a simple projection method to assess the main parameters of these glacier regions under climate change. To achieve this, constructed vertical profiles of mass balance (accumulation and ablation) based both on meteorological data for the 1950–1990s (baseline period) and ECHAM4 for 2049–2060 (projected period) are used, the latter – as a climatic scenario. The observations and scenarios were used to define the recent and future equilibrium line altitude and glacier terminus altitude level for each glacier system as well as areas and balance components. The altitudinal distributions of ice areas were determined for present and future, and they were used for prediction of glacier extent versus altitude in the system taking into account the correlation between the ELA and glacier-terminus level change. We tested two hypotheses of ice distribution versus altitude in mountain (valley) glaciers – "linear" and "non-linear". The results are estimates of the possible changes of the areas and morphological structure of northeastern Asia glacier systems and their mass balance characteristics for 2049–2060. Glaciers in the southern parts of northeastern Siberia and those covering small ranges in Kamchatka will likely disappear under the ECHAM4 scenario; the best preservation of glaciers will be on the highest volcanic peaks of Kamchatka. Finally, we compare characteristics of the stability of continental and maritime glacier systems under global warming.

アジア・アラスカの山岳氷河上の鉱物粒子および有機物のSr, Nd同位体比

アジア・アラスカの山岳氷河上の鉱物粒子および有機物のSr, Nd同位体比