South Asian Perspectives on News of Rapid Himalayan Glacier Melt

The “Third Pole” glaciers of the Himalayas feed into the major rivers of South Asia, providing vital freshwater. This resources is essential to the development of national and local communities and economies. 

With global warming, the Himalayas, along with several other glaciated regions across the planet, are expected to experience a drastic reduction in ice mass and rapidly retreat. A new study tracing Himalayan glacier melt from 1975 to 2016 found that the melt rate has actually doubled since the turn of the century, suggesting a heightened risk of flooding for vulnerable regions. 

The study, published in the journal Science Advances, was conducted by Columbia University Lamont-Doherty Earth Observatory Ph.D candidate Joshua Maurer. Maurer and fellow researchers from Columbia University and the University of Utah examined satellite images to detect changes from the periods of 1975-2000 and 2000-2016. 

This new study received international recognition and gained media attention across several South Asian countries, including Bangladesh.

Bangladesh is a riverine country where three of the major rivers in the region—the Ganges, Meghna, and Brahmaputra—converge and fan out to the Bay of Bengal. These rivers which feed off of Himalayan meltwater provide much-needed freshwater for irrigation, drinking, and other needs.

How might this news impacts the country’s water system?

A view of the Himalayas taken during a trek in Nepal (Source: Treks Himalaya/Flickr)

Bangladeshi perceptions of the study

An AFP article published in The Daily Star, one of the leading English-language Bangladeshi news outlets, asserts that the rapid retreat outlined in the new study threatens the water supply of hundreds of millions of people living downstream across South Asia. It mentions additional contributions to melt aside from temperature, which the study emphasizes as the leading cause of the region’s glacier melt. “Other factors the researchers blamed were changes in rainfall, with reductions tending to reduce ice cover, and the burning of fossil fuels which lead to soot that lands on snowy glacier surfaces, absorbing sunlight and hastening melting,” AFP reported.

UNB and bdnews24 also covered the study. Joseph Shea, a glacial geographer from the University of Northern British Columbia, told bdnews24 that the melting will lead to changes of timing and magnitude of stream flow in a heavily populated region. 

UNB highlighted the study team’s ability to fill critical data gaps by utilizing US spy satellite images to calculate Himalayan ice mass in previous decades. NASA climate scientist John Willis commented that the study’s models provided confirmation of what scientists suspected, which was that warming was the main culprit to extensive melt.

A photo of the Brahmaputra river, the longest river passing through Bangladesh, taken in Mymensingh, Bangladesh (Source: Topu Saha/Flickr)

Glacier contribution to Bangladesh hydrology

GlacierHub interviewed Saleemul Huq, renowned Bangladeshi climate scientist, IPCC author, and director of the International Centre for Climate Change and Development (ICCCAD). Huq provided some general views on the recent news and spoke about the relevance to Bangladesh’s water systems.

“Bangladesh’s Ganges-Brahmaputra-Meghna river basin is highly complex,” Huq said. “Glacier melt makes an important contribution to rivers in dry areas where there is very little rainfall. However, as soon as the monsoon starts, glacier ice melt becomes incomparable to the contribution by heavy monsoon rains.” 

He added that the loss of the glacier overall will impact Bangladesh in the future, yet the immediate increased glacier outflow into the rivers does not heavily effect the hydrology, particularly for the downstream regions. 

Huq said Bangladesh is currently working on some techniques to improve water availability and security for dry seasons, which are expected to become longer with climate change. Some methods include creating barrages, river dredging, and rainwater harvesting. 

The monsoon season (typically June to October) brings nationwide flooding to Bangladesh (Source: Martien van Asseldonk)

Other regions of South Asia

Pakistan media sources, including the Daily Times PK and The Express Tribune, among others, also covered the news. One story published by The Nation PK mentions that, in the long term, millions of people who depend on glacier water during drought years will experience difficulties. In addition, scientists say that the rapid melting of the Himalayas can also result in flooding. This flooding will be exacerbated by heavy monsoon rains. 

Business World India connects the news about the Himalayas with drying taps in Chennai. The greatest impact is said to be in the Indus River system, which is comprised of the Indus, Jhelum, Chenab, Ravi, Beas and Sutlej rivers and is shared by India and Pakistan. The Indus river itself receives about 40 percent of its flow from glacier melt

Already India is suffering from water management issues, and the taps and reservoirs of Chennai are all dried up. In addition to the current weak monsoon and excessive groundwater extraction, future loss of the Himalayas will make the country even more water-stressed. 

Check out this video by The Quint, a popular news website in India, which emphasizes the impacts of Himalayan glacier melt in Asia.

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Video of the Week: Comments from IPCC Chair on SR1.5

This week’s Video of the Week follows the recent release of the IPCC’s special report, SR1.5, on warming impacts of 1.5 degrees Celsius. This short but meaningful video features comments from head of IPCC Hoesung Lee, regarding the observable effects of climate change on societies and ecosystems. SR1.5 urges immediate global response to drastically reduce emissions that contribute to global warming, highlighting the importance of reaching global “net zero” emissions by 2050. The report also suggests strategies for mitigating pathways and transitioning into more sustainable human and environmental systems through adjustments in sectors such as energy, agriculture and infrastructure, to name a few.

Visit the IPCC website for the full report, which includes the Summary for Policymakers and the official press release from Incheon, Republic of Korea. Also, be sure to check out last week’s post on SR1.5 by GlacierHub editor Ben Orlove.

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Glacier Dynamics May Not be Fully Understood

Jakobshavn Isbræ, an outlet glacier off the west coast of Greenland, is losing mass faster than previously thought, due to increased melt water passing through it, as reported in a new paper. The glacier’s rapid trajectory of thinning may well represent the Greenland Ice Sheet (GrIS) ice loss rate in the near future, which could mean faster sea level rise than currently projected.

 

A team of researchers affiliated with the IMAU developed models of  the glacier’s dynamics, and ran 50 tests of these models with different sets of parameterizations such as ocean temperature, ice mass and basal melt until they were able to best match the models with the observed acceleration of Jakobshavn Isbræ. These parameters were then put in place to run the rest of the research. The 2012 acceleration was not captured by the models because it was an exceptional warm melt season that exceeded the mean length of the melt seasons of the previous 20 years; this season caused an exceptionally large amount of meltwater to pass through Jakobshavn Isbræ.

“An intense and long melt year leads to strong thinning of the ice, steepening surface slopes, and has the potential to further sustain the initial acceleration of [Jakobshavn Isbræ],” the authors wrote in their paper. Extreme warming events “may have created the conditions under which the winter slowdowns can no longer compensate for the summer accelerations leading to an increase in the mean annual flow,” they added.

 

Jakobshavn Isbræ calving front
Jakobshavn Isbræ calving front

The acceleration of the ice mass loss of Jakobshavn Isbræ was modelled by 3D representations of the glaciers. There were two known accelerations in the distant past, in 1998 and 2004. The 2003-04 observed event was so intense that the models were unable to represent the amount of mass loss that it sustained. The floating tongue of Jakobshavn Isbræ was ultimately thinned to the point of collapse in the 2003 acceleration event; this collapse led to even more thinning and increased mass loss.

The floating tongue of a glacier provides a terminus point and helps stabilize the glacier. Once a glacier begins to erode to the floating tongue, the acceleration tends to increase and there is even more mass loss than before the break up. (Further explanations of glacier terms can be found here.)

“Findings suggest that the speed observed today at [Jakobshavn Isbræ] is a result of thinning induced changes and a reduction in resistive stress (buttressing) near the terminus correlated with inland steepening slopes,” the authors wrote.

Jakobshavn Isbræ is an important indicator of future sea level rise since it is the largest drainage outlet glacier from the GrIS. It has seen a doubling in acceleration of mass loss and melt water velocity which shows the GrIS is experiencing higher than normal melt seasons.

Jakobshavn Isbræ ice loss and retreat
Jakobshavn Isbræ ice loss and retreat

Due to constraints of typical global models to represent the increased acceleration of ice flow over outlet glaciers during warming events, there is an underestimation of this ice flow’s contribution to overall sea level rise. Increased acceleration of the Jakobshavn Isbræ may be an important piece of the puzzle to help scientists more accurately portray sea level rise in their global models.

This research points to the importance of replicating such analysis in other regions. Other GrIS drainage areas have seen a recent slowdown of ice melt, so this finding may be confined only to one area. However, Jakobshavn Isbræ’s status as the largest of the drainage areas suggests that it may well provide a kind of climatological foreshadowing of future events. According to the authors, climate modelers need to better incorporate the dynamics of glacier mass loss acceleration into their models to better represent potential sea level rise.

 

GRIS ice discharge 1 from AMAP on Vimeo.

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