Lapche Glacier, China Supraglacial Ponds Transitioning to Lake

On October 26, 2018April 26, 2024 By mspeltoIn china glacier retreat, Himalaya glacier retreat

Lapche Glacier (Tibet 1), China in 1992 and 2018 Landsat images. The expansion of supraglacial ponds is evident between Point 2 and 3. A tributary that detaches between 1992 and 2018 is indicated by red arrow. The end of the clean ice and start of debris cover ice is just below Point 1 in 1992 and well above this Point in 2018.

Lapche Glacier (Tibet 1), China flows east from Lapche Kang (Lobuche Kang) in the Bum Chu River Basin. King et al (2017) examined the mass balance of 32 glaciers in the Everest region for the 2000-2015 period including the Lapche, which they called Tibet 1, and found a mass loss of ~0.5 m/year, with the loss of lake terminating glaciers at ~-0.7 m/year. King et al (2017) also observed that a number of these glaciers had nearly stagnant tongues with coalescing and expanding supraglacial ponds. Here we examine the expansion of the supraglacial ponds from 1992 to 2018 using Landsat images.

The lower four kilometers of Lapche Glacier in 1992 is relatively flat with the terminus at 5100 m and four kilometers upglacier at just 5200 m. In this stretch there are several small isolated supraglacial ponds between Point 2 and 3. At Point 1 is the end of the clean ice section of the glacier, with debris cover obscuring the underlying ice below this point. There is a tributary joining the glacier at the red arrow. In 2001 the snowline is at 5600 m, and there are a few more supraglacial ponds, but with a total surface area under 0.1 square kilometers. In 2015 the tributary at the red arrow has detached and the area covered by ponds has expanded and now cover ~0.5 square kilometers. The snowline in 2015 is at 5650-5750 m. In 2018 the supraglacial ponds have largely coalesced, and have an area of ~1.0 square kilometers. These lakes are on the verge of creating one larger lake as has happened on Rongbuk Glacier . The debris covered portion of the glacier now begins above Point 1, 1 km upglacier of its 1992 location. The snowline in 2018 is at 5650-5750 m.

King et al (2018) indicate a velocity of less than 10 m/year in the lower 5 km of the glacier, essentially stagnant. Point 1 is just over 6 km above the 1992 terminus. The retreat here is difficult to discern, but with the proglacial lake development it will soon be identifiable and in line with that of other glaciers in the area Duiya and Yanong. Zhang et al (2010) observed the loss of glacier area and lake expansion in the region from 1976-2006 driven by warming.

Lapche Glacier (Tibet 1), China in map view. Point 1-3 same as in images, ice flow indicated by blue arrows, elevation contours labelled at 51oo and 5200 m. Debris cover beginning noted at DC.

Lapche Glacier (Tibet 1), China in 2001 and 2015 Landsat images. The expansion of supraglacial ponds is evident between Point 2 and 3. A tributary that detaches between 2001 and 2015 is indicated by red arrow.

High Glacier Snow Line Post-Monsoon 2018 on Bhutan-China Border

On October 2, 2018April 26, 2024 By mspeltoIn china glacier retreat, Himalaya glacier retreat

Angge Glacier (A) and Bailang Glacier (B) in China and Chubda Glacier (C) in Bhutan in Post Monsoon 1995 and 2018 Landsat images indicating the snowline purple dots is exceptionally high in 2018. Red arrow is the 1995 terminus location and yellow arrows the 2018 terminus location. Point 1-3 are glacier passes from China into Bhutan.

The end of the monsoon season leads to finally some clear satellite images of snowlines and glaciers in the Himalaya. A Landsat image from September 12, 2018 along the China-Bhutan indicates high snowlines (5500 m) that reach the top of some glaciers and the glacier divide between nations on other glaciers.

Bailang Glacier and Angge Glacier, China are adjacent to the Chubda Glacier, Bhutan. A These glaciers drain north and south from near Chura Kang on the Bhutan/China border. Despite being in different nations on different flanks of the Himalaya, the retreat and resultant lake expansion is the same. These are all summer accumulation type glaciers that end in proglacial lakes. All three lakes are impounded by broad moraines that show no sign of instability for a potential glacier lake outburst flood. The number of glacier lakes in the region has increased 20% (Che et al, 2014) The Chubda Glacier terminates in Chubda Tsho, a glacier moraine dammed lake, Komori (2011) notes that the moraine is still stable and the lake is shallow near the moraine, suggesting it is not a threat for a glacier lake outburst flood. Jain et al., (2015) noted that in the last decade the expansion rate of this lake has doubled. The glacier feeds the Chamkhar Chu Basin.

Here we examine 1995-2018 Landsat images from the post monsoon period to identify both retreat and the anomalously high snowlines in 2018. In 1995 the highest observed snowline is at 5300 m, purple dots, Point 1 -3 are glacier passes from China into Bhutan that are snowcovered. The glaciers terminate at the red arrows. In 2000 the highest observed snowline is 5250-5300 m. There is limited retreat since 1990. In 2017 the highest observed snowline is at 5300-5350 m. In 2018 the highest observed snowline is at 5500-5550 m. The glacier passes at Point 1 and 2 lack any snowcover. The glaciers at Point 3 have no retained snowcover despite top elevation above 5400 m. Bailang Glacier has retreated 900 m from 1995 to 2018 that has led to lake expansion. A retreat 1995-2018 retreat of 800 m of Angge Glacier has led to lake expansion. A retreat of Chubda Glacier of 800 m has led to lake expansion from 1995-2018 has led to lake expansion.

2000 Landsat image from the post monsoon indicating the snowline purple dots. Red arrow is the 1995 terminus location Point 1-3 are glacier passes from China into Bhutan.

2017 Landsat image from the post monsoon indicating the snowline purple dots. Red arrow is the 1995 terminus location Point 1-3 are glacier passes from China into Bhutan.

Sept. 12 2018 Landsat image indicating the snowline purple dots is exceptionally high in 2018. Red arrow is the 1995 terminus location and yellow arrows the 2018 terminus location. Point 1-3 are glacier passes from China into Bhutan.

Mount Tanggula Glaciers, China Thin and Separate

On July 18, 2018April 27, 2024 By mspeltoIn china glacier retreat

Changes in outlet glaciers of Tanggula Shan in Landsat images from 1993 and 2015.

The Tanggula Shan is in the Qinghai-Tibet Plateau at the headwaters of the Yangtze River and host approximately 1000 square kilometers of glaciers. Ke et al (2017) examined glaciers in the Dongkemadi Region of the Qinghai-Tibet Plateau revealed glacier thinning of 0.56 m/year from 2003-2008. The area loss of −0.31 km2/ year from 1976-2013, a 13% change int total area of the glaciers. Chao et al (2017) examined glaciers in the Geladandong region of the Qinghai-Tibet Plateau and found thinning rates of 0.16 m/year from 2003-2009. The thinning was a consequent of temperature increases. Inglis (2016) reported on the ongoing retreats impact on water resources for the Yangtze River.

Here we examine Landsat imagery from 1993-2017 to identify changes at five locations around the Tanggula Icefield. In 1993 outlet glaciers merge at Point 1 and 2. At Point 2 there is a narrow separation between two outlet glaciers. At Point 4 and 5 there is considerable terminus recession of the stagnant hummocky ice (developed in a sublimating environment). Below is a Google Earth image of the glacier at Point #1 illustrating the hummocky nature, Inglis (2016) also provide imagery of this hummocky ice. In 2015 the snowline is high at 5900 m, in this early November image. The terminus of most glaciers is at 5400 m and the head of the glaciers at 6100 m. In November of 2017 the snowline is at 5600 m. The retreat has been significant, but not rapid in this area. This is similar to the retreat of the Suhai Hu Ice Cap in the Qilian Mountains.

Changes in outlet glaciers of Tanggula Shan in Landsat images from 1995 and 2017.

Google Earth image of Tanggula Glacier outlet, Point #1.

Tajuco Glacier Lake, China Expands with Glacier Retreat

On January 3, 2018April 28, 2024 By mspeltoIn china glacier retreat, climate change glacier retreat

Tajuco Glacier terminating in Tajuco Lake retreat in 1994 and 2017 Landsat comparison. Red arrow is 1997 terminus location, yellow arrow is the 2017 terminus location and the purple dots are the snowline in 2017.

Tajuco Glacier Lake is a moraine dammed glacier lake in the Tingri district of China. It drains into the Amur River which flows south into Nepal. Shijin et al (2015) reported on the expansion of the lake from 1990 to 2010 expanding from 0.65 square kilometers to 1.14 square kilometers. They further reported that the Chinese Himalaya had 329 moraine dammed glacier lakes greater than 0.02 square kilometers in area, 116 of these posing a potential hazard, average size of 0.4 square kilometers. The number of lakes across the region is increasing (Kathmandu Post, 2017), though the number of GLOF’s has not. The greater volume of expanding lakes puts more pressure on the moraine, the moraines if they have any ice core or permafrost can also weaken, The moraines with time and distance from the glacier also can consolidate and become more stable.

In 1994 Tajuco Lake was 1.85 km long and had an area of about 0.7 square kilometers. The snowline was at 6400 m. In 1997 glacier retreat had led to an expansion of the lake to 2.05 km. By 2016 the glacier retreat had led to expansion of the lake to a length of 3 km. The snowline is at 6500 m near the crest of the glacier. By 2017 the glacier had retreated 1200 m from 1994 to 2017, a rate of 24 m/year. The snowline was again at 6500 m near the crest of the glacier. The high snowline indicates a glacier that will not survive. retreat will continue to expand the lake. It is likely based on the Google Earth imagery below that the lake will not increase by more than 500 m in length, area in 2017 is 1.20 square kilometers. The retreat and lake expansion is similar to that of other glaciers on the north side of the Himalaya Range in China; Chaxiqudong Glacier, Chutanjima Glacier and Yanong Glacier. The high snowlines have been observed on nearby Rongbuk Glacier at Nup La and on Gangotri Glacier.

Tajuco Glacier terminating in Tajuco Lake retreat in 1997 and 2016 Landsat comparison. Red arrow is 1994 terminus location, yellow arrow is the 2017 terminus location and the purple dots are the snowline in 2016.

Google Earth image of Tajuco Glacier illustrating flow.

Zhongni Glacier Retreat, China and Hydropower

On December 6, 2017April 28, 2024 By mspeltoIn Himalaya glacier retreat

Zhongni Glacier changes from in Landsat images from 1994 to 2015. The red arrow is the 1994 terminus, yellow arrow the 2015 terminus, purple dots the snowline and purple arrows lakes adjacent to the margin of the western glacier in 1994.

Zhongni Glacier is 15 km northwest of Gangotri Glacier just across the border into China. The glacier drains in to the Langgen Zangbo, which becomes the Sutlej River in India. The Sutlej River has a 1000 MW Karcham Wangtoo hydropower plant and a 300 MW Baspa hydropower plant (see below).

The glacier is comprised of three main tributaries separated by two prominent medial moraines. The width of the medial moraine extending to the main terminus is over 200 m. Here we use Landsat imagery to identify the glacier changes from 1994 to 2017.

The western tributary acts as a separate glacier and in 1994 has several adjacent small melt lakes, purple arrow terminating with a narrow band of ice at the red arrow. The snowline is at ~5900 m. The eastern two tributaries extends 700 m further downvalley before terminating. In 2000, there has been retreat of 100-200 m of the western tributary and main glacier, and the snowline is at 5750 m. In 2013 the snowline is at 5800 m. In 2015 the snowline is at 5750 m. By 2015 the western tributary margin has receded from the lakes at the purple arrow. The snowline in 2015 is at 5750 m. In each case the images are far from the fall and the snowline during the post-monsoon season is not the highest elevation. In 2017 there is new snowfall in late November obscuring the snowline. Overall retreat from 1994-2015 of the eastern tributary has been 500 m and of the western tributary 900 m. The western tributary has also lost 200 m of width at the purple arrow. On nearby Gangotri Glacier, India it has been observed that the ablation season has been extending through fall into early winter. The retreat is less pronounced than glaciers terminating in pro-glacial lakes such as Chutanjima Glacier.

Zhongni Glacier changes from in Landsat images of 2000, 2013 and 2017. The red arrow is the 1994 terminus, yellow arrow the 2015 terminus, purple dots the snowline and purple arrows lakes adjacent to the margin of the western glacier in 1994.

Zhongni Glacier in 2012 with the snowline at 5900 m in Digital Glacier imagery. Purple arrows indicate medial moraines.

The Karcham Wangtoo Hydropower (lower yellow arrow) and Baspa Hydropwer station (upper yellow arrow) which both have small reservoirs.

Chaxiqudong Glacier, Tibet Retreat From Lake & Tributary Separation

On November 1, 2017April 28, 2024 By mspeltoIn Himalaya glacier retreat

Chaxiqudong Glacier (C) at right and Paqu Glacier (P) at left in Landsat images from 1992 and 2017. The red arrow indicates the terminus in 1992 and the yellow dots the 2017 margin. Purple arrow indicates a glacier that disappeared and orange arrow separation of Paqu Glacier. Both glaciers no longer reach the lake.

Chaxiqudong Glacier and Paqu Glacier are located in a sub-range north of the Nepal-China border. Chaxiqudong Glacier is adjacent to Longmiojian Glacier. The glaciers drain into Nepal entering the Bhote Khosi River. The Bothe Khosi had a hydropower project that has been put out of service by a 2015 earthquake and 2016 flood event. King et al (2017) observe significant surface lowering in the ablation zone of both glaciers (Figure 2), though less than on neighboring larger glaciers. Zhang et al (2010) observed the loss of glacier area and lake expansion in the region from 1976-2006. Here we examine Landsat imagery from 1992 to 2017 to observe changes.

Chaxiqudong Glacier terminus in 1992 is in a proglacial lake at the junction of a pair of tributaries red arrow). Paqu Glacier has a wide terminus in a proglacial lake (red arrow). By 2001 Chaxiqudong Glacier has separated with the eastern tributary still at the margin of the proglacial lake and the western tributary having receded from the lake. Paqu Glacier still is in contact with the lake on a narrow front on the west margin of the lake. By 2015 both tributaries of the Chaxiqudong Glacier have receded significantly from the lake. Paqu Glacier has retreated from the lake and has separated into two sections, orange arrow. By 2017 Chaxiqudong Glacier has retreated 400 m since 1992, no longer terminates in a lake and has separated into two glaciers (yellow arrow). Paqu Glacier has retreated 5oo m no longer terminates in a lake and has separated into two glaciers (yellow arrow). The retreat of each glacier has occurred without significant calving indicating a retreat driven by negative surface mass balance. The retreat is less than on the larger Yanong and North Yanong Glacier to the east that also end in lakes still. The retreat of these glaciers from the lakes also reduces the threat of glacier lake outburst floods, as both the risk of calving and avalanches caused rapid water level change have declined. At the purple arrow is a small cirque glacier in 1992. This glacier still exists in 2001, but has disappeared by 2015.

Chaxiqudong Glacier at right and Paqu Glacier at left in Landsat images from 2001 and 2015. The red arrow indicates the terminus in 1992. Purple arrow indicates a glacier that disappeared. Both glaciers no longer reach the lake.

Gangge’er Glacier, Retreat & Tributary Separation Qilian Mt. China

On October 24, 2017April 28, 2024 By mspeltoIn china glacier retreat, climate change glacier retreat

Gangge’er Glacier, Qilian Mt., China comparison in 1997 and 2017 Landsat Images. Yellow arrows indicates 2017 terminus, red arrows the 1990 terminus, and purple arrows tributaries that have detached. The snowline is purple dots and Points 1-3 indicate bare rock areas amidst the glacier.

The largest glacier in the Gangge’er Xiaoheli Shan range of the the Qilian Mountains in China, here referred to as Gangge’er Glacier, drains northwest into the Shule River. Glaciers in the Qilian Mountains in northwest China’s Gansu Province have shrunk by 36 square kilometers, a 4.2 percent loss, during the past decade Quiang (2016). Tian et al (2014) report Qilian Mountain glacier area shrank by 30% from 1956 to 2010 and the shrinkage accelerated remarkably in the past two decades. Yang et al (2015) Results show that mountain glaciers in China are very vulnerable to climate change with 41% of glaciers having had a high vulnerability in the period 1961–2007. For the Upper Shule Basin the impact of glaciers on the overall water resource is not known as Li and Yang (2017) observe that that the basic features of precipitation in the upper reaches of the Shule River were unexplored prior to their study and there is no national weather station in the basin. They found that most of the precipitation occurred during the summer.

What is apparent in a comparison of Landsat images from 1997-2017 is the changes in the glacier. In 1997 the glacier is joined by three main tributaries from the south and four from the north. The western most from the north and south are noted by the purple arrow. The glacier terminates at the red arrow and the snowline is low on the glacier at 4600 m, likely after a summer snowstorm. The areas of bedrock amidst the glacier at Points 1-3 are limited. In 1999 the snowline is above the main stem of the glacier at 4800 m. There has been limited change since 1997, there is a small cloud causing a ground shadow right at the terminus. By 2016 and 2017 the westernmost tributary from the north and south have detached from the glacier , purple arrows. The areas of bedrock amidst the glacier at Point 1-3 have all expanded indicating upglacier thinning. The terminus has retreated to the yellow arrow a distance of 900 m in 20 years. In the digital globe image below extensive surface streams indicate significant meltwater drainage up to 4900 m, above the snowline in both images. The surface streams indicate a cold layer of ice preventing surface meltwater infiltration.

Gangge’er Glacier, Qilian Mt., China comparison in 1999 and 2016 Landsat Images. Yellow arrows indicates 2017 terminus, red arrows the 1990 terminus, and purple arrow tributary that has detached. Points 1-3 indicate bare rock areas amidst the glacier.

Google Earth image of the glacier indicating flow directions dark blue arrows, surface streams light blue arrows and separated tributaries purple arrows.

Cook Ice Cap Outlet Glacier Retreat Lake Fromation, Kerguelen 2001-17

On February 10, 2017May 1, 2024 By mspeltoIn glacier climate change, kerguelen island glacier retreat

Comparison of eastern outlet glaciers of the Cook Ice Cap in 2001 and 2017 Landsat images. Red arrow indicates a location of tributary separation. Pink arrow the 2017 terminus location of the northernmost glacier. Orange arrow the 2017 terminus location of the middle glacier. Yellow arrow tip the 2001 terminus position of glacier ending in newly formed lake. Green arrow the southernmost glacier 2017 terminus location.

On the east side of the Cook Ice Cap on Kerguelen Island a series of outlet glaciers have retreated expanding and forming a new group of lakes. Here we examine the changes from 2001-2017 along using Landsat imagery. Retreat of glacier in the region was examined by Berthier et al (2009) and is exemplified by the retreat of Ampere Glacier. Verfaillie et al (2016) examined the surface mass balance using MODIS data, field data, and models. They identified that accelerating glacier wastage on Kerguelen Island is due to reduced net accumulation and resulting rise in the transient snowline since the 1970s, when a significant warming began.

In 2001 at the red arrow is where the north tributary of a glacier ending in the northern most lake joins the main glacier. In the second lake is a peninsula, marked with point A that the glacier terminus is 1 km from. The next two glaciers terminating at the yellow arrow and beyond the green arrow do not have lakes at their termini. By 2014 the northern tributary has lost its connection with the main glacier terminating in the lake. The distance from the island for the middle glacier has increased. A lake is forming at the yellow arrow. For the third glacier a lake has formed at the green arrow. In 2017 the northern glacier has retreated to the pink arrow a distance of 750 m and is no longer terminating in the lake. The terminus at the orange arrow has retreated main terminus has retreated 900 m, expanding the lake it terminates in. The glacier at the yellow arrow has retreated into a new lake basin, with a retreat of 850 m since 2001. The terminus is thin and in the Google Earth image indicates some substantial thin icebergs have separated from the glacier. The green arrow marks the 2017 terminus of the southern most lake. This glacier has retreated 950 m leading to the continued expansion of a new lake. In just a decade we see the formation of two new lakes and the expansion of two others at the terminus of the eastern outlet glaciers of Cook Ice Cap, rapid landscape change driven by climate change.

2014 Landsat image of the eastern outlet glaciers of Cook Ice Cap.Red arrow indicates a location of tributary separation. Pink arrow the 2017 terminus location of the northernmost glacier. Orange arrow the 2017 terminus location of the middle glacier. Yellow arrow tip the 2001 terminus position of glacier ending in newly formed lake. Green arrow the southernmost glacier 2017 terminus location.

Terminus of three outlet glaciers from left to right the green arrow, yellow arrow and orange arrow terminus glacier on the Landsat images. The green arrows indicate places where the terminus or icebergs illustrates how thin the glacier ice is.

Laigu Glacier, China Retreat Lake Expansion

On December 16, 2016May 1, 2024 By mspeltoIn china glacier retreat

Landsat image comparison of the Laigu Glacier in 1988 and 2015. The red arrow indicates the 1988 terminus and the yellow arrow the 2015 terminus location. The purple dots in 2015 indicate the snowline.

Laigu (Lhagu) Glacier, China is in the Kangri Karpo Mountains of the Southeast Tibet Plateau and drains into the Salween River. This is the largest glacier in its region at 32 km in length. The glacier terminates in an expanding proglacial lake, Laigu Lake. Here we examine changes in Landsat imagery from 1988 to 2015 to identify response to climate change. Wang and others (2011) note that glacial lakes have expanded from 1970-2009 by 19% and the area that is glacier covered has decline by 13% during the 1970-2009 period in the nearby Boshula Range. At the AGU this week research based on Landsat imagery indicates a 20% per decade velocity decline on the glacier (Landsat Science, 2016).

In 1988 Laigu Glacier terminated in the proglacial lake that was 2 km across from north to south and 1.3 km from east to west. By 2001 the lake had expanded to 1.6 km from east to west. The transient snow line is at 4300 m. In November, 2014 the snowline is at 4700 m. In October, 2015 the snowline is at 4700 m again. The glacier has retreated 1900 m from its 1988 terminus along the southern shore of the expanding lake and 900 m along the northern shore. The expansion of the lake along the southern shore is evident in the 2004 and 2014 Google Earth segmented image below, note the pink arrows. The high snowline indicate a reduced accumulation, which reduces the flux into the ablation zone, this is evident in the reduced glacier velocity noted by Dehecq (2016). The reduced velocity will lead to a continued retreat of the glacier and expansion of the lake. This region has experienced a sustained rise in summer temperatures (Wang and others, 2011). The snowlines remaining high into November indicates warmer conditions in the post summer monsoon season also. The high snowlines and lake expansion due to glacier retreat is a familar story in the region, Chutanjima Glacier and Menlung Glacier.

Landsat image comparison of the Laigu Glacier in 2001. The red arrow indicates the 1988 terminus and the yellow arrow the 2015 terminus location. The purple dots in 2001 indicate the snowline.

Landsat image comparison of the Laigu Glacier in 2014. The red arrow indicates the 1988 terminus and the yellow arrow the 2015 terminus location. The purple dots in 2014 indicate the snowline.

Google Earth image of the region indicating the lake expanding from the pink arrow at right to the pink arrow at left from 2004 to 2014.

Summer temperature rise form Wang and others (2011).

Chutanjima Glacier Retreat & High Snowline, Tibet, China 1991-2015

On June 21, 2016May 2, 2024 By mspeltoIn china glacier retreat, climate change glacier retreat, glacier climate change, Glacier Observations

A comparison of three Tibet glaciers in 1988, 1991 and 2015 Landsat images. Red arrows are the 1988 terminus position, yellow arrow the 2015 terminus location and purple dots the snowline in late October 2015. U=unnamed, CH=Chutanjima Glacier and MO=Mogunong Glacier: which did not retreat significantly and lacks a red arrow.

A recent European Space Agency Sentinel-2A image of southern Tibet, China and Sikkim illustrated three very similar glaciers extending north from the Himalayan divide on the China-India Border. We examine these three glacier in this post. The three glaciers all drain into the Pumqu River basin, which becomes the Arun River. The largest is unnamed the two easternmost are Chutanjima and Mogunong Glacier.The glaciers all have similar top elevations of 6100 -6200 m and terminus elevations of 5260-5280 m. All three are summer accumulation type glaciers with most of the snow accumulating during the summer monsoon, though this is also the dominant melt period on the lower glacier. Wang et al (2015) examined moraine dammed glacier lakes in Tibet and those that posed a hazard, none of the three here were identified as hazardous. The number of glacier lakes in the Pumqu Basin has increased from 199 to 254 since the 1970’s with less than 10% deemed dangerous, but that still leaves a substantial and growing number (Che et al, 2014). Here we compare Landsat images from 1988, 1992 and 2015 to identify their response to climate change. The second Chinese Glacier inventory (Wei et al. 2014) indicated a 21% loss in glacier area in this region from 1970 to 2009.The pattern of retreat and lake expansion is quite common as is evidenced by other area glaciers, such as Gelhaipuco, Thong Wuk, Baillang Glacier and Longbashaba Glacier.

In the 1988 image all three glaciers terminate at the southern end of a proglacial lake with seasonal lake ice cover, red arrows. In 1991 the lakes are ice free and have some icebergs in them. By 2015 the retreat has been 500 m for the easternmost glacier, 400 m for Chutanjima Glacier and 100 m at most for Mogunong Glacier. Each glacier has remained extensively crevassed to the terminus indicating they remain vigorous. The retreat is greatest for the two ending in expanding lakes. Mogunong Glacier appears to be near the upper limit of the lake, and is not calving, which likely led to less retreat. An icefall is apparent 700 m from the front of Mogunong Glacier. The width of the glacier below this point has diminished considerably from 1988 to 2015, though retreat has been minor, indicating a negative mass balance. There is an icefall 1 km from the icefront of Chutanjima, indicating the maximum length the lake would reach.

The Sentinel image indicates an important characteristic and trend in the region. This is an early February image and the snowline is quite high on the glacier in the midst of winter. The snowline is at 5850-5900 m nearly the same elevation as in late October of 2015 seen above. This illustrates the lack of winter accumulation that occurs on these summer accumulation glaciers. It also indicates a trend toward ablation processes remaining active, though limited from November-February. The lack of snowcover on the lower glaciers as the melt season begins hastens ablation zone thinning, mass balance loss and retreat.

Europenan Space Agency, Sentinel-2A image from 1 February 2016. Orange arrow indicates icefalls and purple dots the snowline.

2014 Google Earth image of the region. Orange arrows indicate icefalls, note the crevassing extending to glacier front.

Bailang Glacier and Angge Glacier Retreat, China 1995-2015

On June 7, 2016May 2, 2024 By mspeltoIn china glacier retreat, climate change glacier retreat, Himalaya glacier retreat

Comparison of 1995 and 2015 Landsat image illustrating 1995 (red arrows) and 2015 terminus locations (yellow arrows) of Bailang Glacier (B) and Angge Glacier (A). Purple arrows indicate areas upglacier of expanding bedrock due to glacier thinning. Head of Chubda Glacier (C), Bhutan indicated.

Bailang Glacier and Angge Glacier, China are adjacent to the Chubda Glacier, Bhutan. Despite being in a different nation on a different side of the Himalaya, the behavior is the same. These are both summer accumulation type glaciers that end in proglacial lakes. Both lakes are impounded by broad moraines that show no sign of instability for a potential glacier lake outburst flood. The number of glacier lakes in the adjacent Pumqu Basin to the west has increased from 199 to 254 since the 1970’s with less than 10% deemed dangerous (Che et al, 2014) Here we compare Landsat images from 1995 and 2015 to identify their response to climate change. The second Chinese Glacier inventory (Wei et al. 2014) indicated a 21% loss in glacier area in this region from 1970 to 2009.

Bailang Glacier in 1995 terminated in a proglacial lake that was 2.1 km long at an elevation of ~5170 m, red arrow. Angge Glacier terminated in a lake that was 1 km long at an elevation of ~5020 m. By 2001 both glaciers had experienced minor retreat of less than 250 m. By 2014 both lakes had expanded considerably due to retreat, no significant change in water level had occurred. By 2015 Bailang Glacier had retreated 800-900 m and the lake was now 3 km long. A key tributary on the west side near the yellow arrow had also detached. There is no significant slope change in the lower 1 km of the glacier indicating retreat should continue enhanced by melting in and calving in the proglacial lake. For Angge Glacier retreat from 1995 to 2015 was 700 to 800 m, with the glacier retreating to a westward bend in the lake basin. The glacier has an icefall just above the current terminus suggesting the lake basin will soon end, which should slow retreat. The pattern of retreat and lake expansion is quite common as is evidence by Gelhaipuco, Thong Wuk and Longbashaba Glacier.

2001 Landsat image illustrating 1995 (red arrows) and 2015 terminus locations (yellow arrows) of Bailang Glacier (B) and Angge Glacier (A). Head of Chubda Glacier (C), Bhutan indicated.

2014 Landsat image illustrating 1995 (red arrows) and 2015 terminus locations (yellow arrows) of Bailang Glacier (B) and Angge Glacier (A). Head of Chubda Glacier (C), Bhutan indicated.

Jiongla Glacier, China Rapid Retreat 1988-2015

On March 3, 2016May 2, 2024 By mspeltoIn china glacier retreat, glacier climate change, Glacier Observations

Jiongla Glacier retreat right and Jiangyegong Glacier left retreat from 1988 to 2015 in Landsat images. The red arrow is the 1988 terminus and the yellow arrow the 2015 terminus. Jiongla Glacier retreated 3200 m and Jiangyegong Glacier 800 m.

Jiongla Glacier is at the northern boundary of the Brahmaputra River Basin at the east end of the Nyainqentanglha Shan. The glacier drains the western slopes of Koma Kangri Peak and ends in a lake before feeding into the Parlung Zangbo and then Yarlung Tsanpo. his glacier feeds the Parlung Zangbo which is the site of numerous planned hydropower projects, last image, before joining the Yarlung Tsanpo which becomes the Brahmaputra River. The Zangmu Dam went online in 2015, this hydropower facility will produce 2.5 billion kilowatt-hours of electricity a year. In a study by Tobias Bolch et al (2010) in the western Nyainqêntanglha Mountains glacier area decreased by 6% between 1976 and 2001 and continued to shrink from 2001–2009. Li et al (2010) examined glacier change over the last several decades in China and found ubiquitous glacier retreat and commonly lake formation as glaciers retreated. Ninglian and Shichang (2014) in the China National Report on Cryospheric Sciences noted a loss in glacier area of 15 to 17 % in the region. Here we examine satellite imagery from 1988, 2000, 2009, 2010, 2011 and 2015. The red arrow denotes the 1988 terminus and the yellow arrow the 2011 terminus.

In 1988 the lake where Jiongla Glacier ends is at 2 km long. By 2000 the glacier has retreated 1300 meters. In the 2003 terminus closeup that indicates vigorous flow through an icefall, purple arrow, 2 km behind the terminus. This indicates the lake will end before this point and the glacier does not have a substantial stagnant terminus tongue. By 2011 the lake is 4 km long, a 2 km retreat in 20 years. There are icebergs visible in the lake particularly in the 2003, 2009 and 2011 images indicating that this one a key reason for rapid recent retreat. In reviewing the satellite images for the region cloud cover made it difficult to find imagery near the end of the melt season. By 2015 the lake is 5200 m long indicating a 3200 m retreat from 1988-2015. The terminus is now within 500 of the increase in surface slope that suggests the end of the lake, and likely the end of the current rapid retreat. The 2011 image is from near the end of the melt season and indicates a snowline at 5150 m, blue dots, this is too high for equilibrium, with limited glacier area above 5500 m and the terminus at 4000 meters. This suggests that retreat will continue. The retreat here is similar to that of Thong Wuk Glacier and Requiang Glacier.

The neighboring Jiangyegong Glacier has experienced an 800 m retreat from 1988 to 2015. This terminus remains low slopes and heavily debris covered. The debris will slow the retreat, while the low slope indicates the lake can continue to expand enhancing retreat. This also suggests the rate of retreat will soon slow.T