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A new method for the efficient synthesis of 1,3-adamantanediol is proposed. It has the advantages of good reaction selectivity, high isolated yield, easy purification, and safe operation. 3-Hydroxyadamantane-1-carboxylic acid reacts first with thionyl chloride to form 1,3-dichloro adamantane, which is then converted to 1,3-adamantanediol in a “triethylamine–water” solution. Three reaction types are involved: chlorination, decarbonylation, and hydrolysis. Under optimal reaction conditions, total isolated yields of up to 95% and purities of up to 99% were achieved. Isolated yields of 100 g per batch have been achieved, with potential for industrial production. We completed the decarbonylation of acyl chloride without the use of a metal catalyst. In addition, the reaction mechanism was investigated by combining experimental data and density functional theory.

Based on the revised First Chinese Glacier Inventory (FCGI), the Second Chinese Glacier Inventory (SCGI) and Landsat OLI images for 2015–2016, we analyzed the spatial-temporal variation characteristics of glaciers in the Gangdisê Mountains from 1970 to 2016. The results showed that there were 3953 glaciers with a total area of 1306.45 km2and ice volume of ~58.16 km3in the Gangdisê Mountains in 2015–2016. Glaciers with sizes of 0.1–5 km2and <0.5 km2accounted for the largest area and the most amounts of glaciers in the Gangdisê Mountains, respectively. Over the past five decades, the area of glaciers in the Gangdisê Mountains decreased by 854.05 km2(−1.09%a−1), accounting for 39.53% of the total glacier area in 1970. The increase in temperature during the ablation period was the most important cause for glacier retreat. Compared to other mountains in western China, the Gangdisê Mountains have experienced the strongest glacial retreat, and the rate of recession has increased in recent years. The decrease of glacier area was mainly concentrated at elevations of 5600–6100 m, and no change in glacier area was observed at elevations above 6500 m. The number and area of glaciers decreased in all orientations in the Gangdisê Mountains except for south- and southeast-oriented glaciers. Among them, north-oriented glaciers suffered the largest loss of glacier area, while glacier retreat saw the fastest in northwest-oriented glaciers. The rate of glacier retreat increased from west to east in the Gangdisê Mountains. The relative rate of glacier area change was the highest in the eastern section of the Gangdisê Mountains (−1.72%a−1), followed by the middle section (−1.67%a−1) and the western section (−0.83%a−1).

Glaciers are the most important fresh-water resources in arid and semi-arid regions of western China. According to the Second Chinese Glacier Inventory (SCGI), primarily compiled from Landsat TM/ETM+ images, the Qilian Mountains had 2684 glaciers covering an area of 1597.81±70.30 km2 and an ice volume of ~84.48 km3from 2005 to 2010. While most glaciers are small (85.66% are <1.0 km2), some larger ones (12.74% in the range 1.0–5.0 km2) cover 42.44% of the total glacier area. The Laohugou Glacier No.12 (20.42 km2) located on the north slope of the Daxue Range is the only glacier >20 km2in the Qilian Mountains. Median glacier elevation was 4972.7 m and gradually increased from east to west. Glaciers in the Qilian Mountains are distributed in Gansu and Qinghai provinces, which have 1492 glaciers (760.96 km2) and 1192 glaciers (836.85 km2), respectively. The Shule River basin contains the most glaciers in both area and volume. However, the Heihe River, the second largest inland river in China, has the minimum average glacier area. A comparison of glaciers from the SCGI and revised glacier inventory based on topographic maps and aerial photos taken from 1956 to 1983 indicate that all glaciers have receded, which is consistent with other mountain and plateau areas in western China. In the past half-century, the area and volume of glaciers decreased by 420.81 km2(–20.88%) and 21.63 km3(–20.26%), respectively. Glaciers with areas <1.0 km2decreased the most in number and area recession. Due to glacier shrinkage, glaciers below 4000 m completely disappeared. Glacier changes in the Qilian Mountains presented a clear longitudinal zonality, i.e., the glaciers rapidly shrank in the east but slowly in the central-west. The primary cause of glacier recession was warming temperatures, which was slightly mitigated with increased precipitation.

Surges and glacier avalanches are expressions of glacier instability, and among the most dramatic phenomena in the mountain cryosphere. Until now, the catastrophic collapse of a glacier, combining the large volume of surges and mobility of ice avalanches, has been reported only for the 2002 130 × 106m3detachment of Kolka Glacier (Caucasus Mountains), which has been considered a globally singular event. Here, we report on the similar detachment of the entire lower parts of two adjacent glaciers in western Tibet in July and September 2016, leading to an unprecedented pair of giant low-angle ice avalanches with volumes of 68 ± 2 × 106m3and 83 ± 2 × 106m3. On the basis of satellite remote sensing, numerical modelling and field investigations, we find that the twin collapses were caused by climate- and weather-driven external forcing, acting on specific polythermal and soft-bed glacier properties. These factors converged to produce surge-like enhancement of driving stresses and massively reduced basal friction connected to subglacial water and fine-grained bed lithology, to eventually exceed collapse thresholds in resisting forces of the tongues frozen to their bed. Our findings show that large catastrophic instabilities of low-angle glaciers can happen under rare circumstances without historical precedent. Two catastrophic glacier collapse events in western Tibet in 2016 were caused by a convergence of weather and glacier-bed conditions, according to an analysis of observations and modelling.

To characterize the spatiotemporal variations of glacier surface speed on the Kenai Peninsula, Alaska (∼3,900 km2), we derived 92 surface speed fields between October 2014 and December 2019 using intensity offset tracking on Sentinel‐1 data. On average, speeds are 50% greater in spring (March‐May) than the annual mean (69 m a−1) while winter speeds are close to the annual mean. While marine‐terminating glaciers have their maximum speed near the terminus, both land‐ and lake‐terminating glaciers flow fastest around the median glacier elevation. On average, the lake‐terminating and tidewater glaciers flow 1.7 and 2.3 times faster than the land‐terminating glaciers, respectively. Monthly variations over the 5‐year period are strikingly synchronous regardless of terminus type suggesting that regional‐scale meteorological drivers govern the temporal variability. Mean annual speeds fluctuate roughly ±10% of the period mean without an apparent trend. At lake‐terminating Bear Glacier, a short‐term tripling in ice speed in fall 2019 over the area below an ice‐dammed lake coincides with an observed glacier lake outburst flood (GLOF). An earlier GLOF caused a persistent breach of the beach barrier between the proglacial lake and ocean which likely led to overall speed‐up of the lower glacier part throughout 2019. A significant speedup was also observed at the lower part of the lake‐terminating Ellsworth Glacier and attributed to rapid glacier retreat and lake expansion, probably further amplified by the terminus area becoming buoyant and a large tabular iceberg breaking off. Our results highlight the impact of GLOFs and proglacial characteristics in spatial and temporal glacier speed variations. Glaciers constantly move but the speed varies with time and space. We use satellite data to calculate the surface ice speed variations of all glaciers on the Kenai Peninsula, Alaska (∼3,900 km2), between October 2014 and December 2019. On average, the glacier speed is 50% higher in spring than the annual average. Overall, the lake‐terminating glaciers flow 70% faster, and marine‐terminating glaciers more than 100% faster than the land‐terminating glaciers. Over the 5‐year period, all glaciers regardless of terminus type tended to speed up or slow down simultaneously, probably driven by large‐scale variations in weather governing the water supply to the drainage system. The lower part of Bear Glacier tripled in speed in fall 2019 when an ice‐dammed lake suddenly drained through the glacier. Another glacier outburst flood in 2018 led to a breach of the beach barrier between the large lake at the glacier terminus and the ocean which might have caused the considerable speedup of the lower glacier part throughout 2019. Lake‐terminating glaciers flow 1.7 times and tidewater glaciers 2.3 times faster than the land‐terminating glaciersMonthly ice speed variations are largely synchronous across the Peninsula irrespective of terminus typeA glacier outburst flood at Bear Glacier caused both a short‐term and a longer‐term speed‐up of the glacier's lower part Lake‐terminating glaciers flow 1.7 times and tidewater glaciers 2.3 times faster than the land‐terminating glaciers Monthly ice speed variations are largely synchronous across the Peninsula irrespective of terminus type A glacier outburst flood at Bear Glacier caused both a short‐term and a longer‐term speed‐up of the glacier's lower part