After ‘Peak Water,’ the Days of Plenty Are Over

In a recent paper in Science of The Total Environment, a team of Chinese researchers created a model of the Urumqi No. 1 catchment in Xinjiang, China, and made a surprising discovery. As they sought to estimate the effects of global warming on glacier thinning, retreat and local supply of water resources, they found that the glacier is expected to reach “peak water,” with runoff shrinking by half of its 1980 extent in the next 30 years. The glacier will also lose approximately 80 percent of its ice volume.

As glaciers shrink, runoff increases (with more melting) but then decreases thereafter when the size of the glacier has permanently decreased. Peak water, or the tipping point of glacier melt supply, when runoff in glacier-fed rivers reaches the maximum, is estimated to occur around 2020. This phenomenon shares its concept with the term “peak oil,” which refers to the hypothetical point in time when the global oil production rate will reach maximum capacity. Thereafter, oil production will only decline.

Urumqi No. 1 Glacier on GlacierHub
Urumqi No. 1 Glacier (Source: Far West China/Pinterest).

In contrast to peak oil, glacial reserves can be estimated with a higher certainty. Annina Sorg, an independent researcher with expertise in geomorphology, geography and climatology, explained the concept to GlacierHub. “Peak water for a catchment can be assessed with quite good precision if the past climate and glacial volume loss are well known and if reasonable climate models are being used,” she said. This is because, unlike oil, consumption of glacier meltwater does not have a direct impact on glacial melting. Glaciers will continue to melt no matter if the demand for glacial meltwater is high or low.

“Peak water is an important aspect of glacial impact of hydrology, and the term absolutely makes sense,” Matthias Huss, a senior lecturer from the University of Freiburg, expressed in an interview with GlacierHub. “After peak water, annual runoff sums from glaciers will be steadily decreasing, which might cause problems with water availability.”

Huss’s team recently published a paper on the first complete global assessment of when peak water from glaciers will occur. Huss believes the smaller scale study on the Urumqi glacier uses a very similar approach as he did for all 200,000 glaciers globally but with more accurate data for calibration and validation to fit the local context. Both studies also yield consistent findings.

In the arid regions of Central Asia, meltwater from glaciers determine streamflow. Glaciers are not only valuable water sources for the communities around rivers, but can also serve as buffers against droughts during dry periods.

“Conditions are ‘good’ before peak water— we even have more water than in the case of balanced glacier mass budgets. This water can be used for irrigation or hydropower production. However, after peak water, less water is available, most importantly in the summer months, which might have considerable impact on water resource management,” Huss warned.

Urumqi River on GlacierHub
Urumqi River that is fed by the Urumqi No. 1 Glacier (Source: Remote Lands/Pinterest).

The story is also more complex in a broader context. Whether water shortage is experienced due to glacier recession strongly depends on the climate regime. In general, glaciers play a more important role when summer climates are dry, as in the case of Xinjiang. Peak water also strongly varies with glacier size, with larger glaciers experiencing later peaks than smaller glaciers.

“As Urumqi Glacier is a relatively small glacier, it might not be fully representative for regional peak water, which is governed by the larger glaciers,” Huss explained.

Still, Sorg holds the view that the abundance of meltwater before peak water “might slow down a society’s attempts to elaborate mitigation measures, which would be needed to handle the second period of decreasing meltwater runoff.”

In the case of Xinjiang, runoff from glacier melting will likely experience a dramatic decrease from 2020 to 2050, post peak water. The east and west branches of Urumqi No. 1 Glacier also have different responses to climate change. By the end of the 21st century, as compared to 1980 rates, the area extent and ice volume of the west branch could decrease by up to 58 and 82 percent, respectively. While at the east branch, glacier area could shrink by 95 percent, losing about 99 percent of its ice volume.

Urumqi Glacier Change on GlacierHub
Predicted Glacier Area Changes in 2030, 2050, 2070 and 2100 based on RCP 4.5 and 8.5 (Source: Gao et al).

 

“In my opinion, it is important to spread the term ‘peak water,’ also in popular media, not science alone. It draws awareness to the point that the depletion of glacial reserves is not a continuous process like emptying a bathtub,” Sorg told GlacierHub. Rather, peak water is a period of abundance that Sorg thinks is probably not appreciated enough and is taken for granted.

Sorg concluded with a somber reminder. “After peak water, the days of plenty are over— at least in respect to glacial meltwater availability,” she said. As Xinjiang is very dependent on its glaciers, mitigation measures are required to adapt to glacier mass changes for long-term water security in the region.

Crevasses Offer Clues About Glacial Dynamics

A recent article accepted in the Reviews of Geophysics summarizes research on how crevasses form and affect glaciers. Crevasses are fractures in the glacier surface that are renowned for their danger but also have been a research focus for glaciologists and other physical scientists for the past several decades, a subject which William Colgan of York University in Canada and his co-authors examine in detail.

Water enters the depth of a crevasse on the Langjökull glacier, Iceland. Courtesy of Flickr user Ville Miettenin.
Water enters the depth of a crevasse on the Langjökull glacier, Iceland. Courtesy of Flickr user Ville Miettenin.

“Because of the non-trivial safety hazard associated with accidental crevasse falls, crevasses have been a bit of an afterthought in most observational glaciology studies to date,” Colgan told GlacierHub. “In this review, we tried to pull together various crumbs of crevasse insight from about 200 studies published over the past sixty years.”

As glaciers move, the ice within them deforms, expands and contracts, and crevasses form as a result of the resulting tensions in the ice. Glacier ice is constantly in the process of moving, and generally flows downslope from the higher accumulation zone, where snowfall contributes to building up glacier ice, to the lower ablation zone, where ice is lost through sublimation, melting, or iceberg calving. The ice experiences differential stresses as it travels over bumps on the bedrock below, or in areas where the slope changes, leading to cracking.

Another source of stress occurs as ice flows through areas of changing lateral boundaries; these constrict the ice or allow it to spread more widely. Like liquid water in a river, glacier ice speeds up in certain areas and slows down in others. The differential pushes and pulls causes the ice to split. Crevasses can occur in varying locations along a glacier, including curves and straightaways, and on both the top and bottom surfaces of glaciers.

“Ice generally deforms and flows like a fluid, albeit a really, really, viscous fluid,” Colgan said. “Sometimes, however, the stresses exerted on a parcel of ice change too quickly for plastic deformation, and the ice experiences brittle fracture instead, forming crevasses. The distribution of crevasses on a glacier can change with both space and time, which makes crevasses interesting indicators of glacier dynamics.”

An analysis of stresses in a glacier. Crevasses usually open in the direction the glacier expands, which is indicated by the red lines. Courtesy of William Colgan.
An analysis of stresses in a glacier. Crevasses usually open in the direction the glacier expands, which is indicated by the red lines. Courtesy of William Colgan.

Crevasses form, but they can also seal up, like a healing wound, and disappear. Scientists have been conducting research on this lifecycle. When crevasses rapidly appear and then close up within a short span of the glacier’s movement, it is referred to as a low-advection life cycle. If crevasses open up, and persist for a long time as the glacier moves long distances to conditions favorable to sealing up, that is referred to as a high-advection lifecycle. An analysis of published studies suggest that low-advection lifecycles are more common in the ablation zone while high-advection lifecycles are more common in the accumulation zone.

Crevasses’ spatial dimensions determine how they influence the movement of the overall glacier. The authors write that the most important area for research is understanding how deep crevasses will be once they form, rather than their width. Deep crevasses allow water to penetrate further into the body of the glacier. Just as melting ice absorbs heat, this freezing water releases heat into the glacier. Even small amounts of heat can have large impacts on the glacier flow rate, and the deeper this heat is released in the glacier, the greater its impact on ice movement. Faster glacier movement can lead to greater loss of glacial ice, especially by increased calving into the ocean, since this accelerated downslope movement will not change the rate of glacier formation in higher zones.

Crevasse rescuers practice in New Zealand. Courtesy of Flickr user Vielle Miettenin
Crevasse rescuers practice in New Zealand. Courtesy of Flickr user Vielle Miettenin

Data on the depth of crevasses is limited. Many crevasses are covered by thin snow bridges that make them invisible, both to scientists who are trying to study them and to hikers and others who would rather stay away from them. The authors of the study searched for the published record of an air-filled crevasse depth and initially found it not in a study of crevasses but in a report of a skier who was rescued at a depth of 34 meters inside one. Additional reports surfaced through their research, and they report several published accounts of air-filled crevasses exceeding 45 meters in depth. Measurement is difficult, but new robots carrying ground-penetrating radar are coming into use to take measurements of crevasses and identify hazards.

While the interaction of water and deep crevasses is relatively complex, there is a more obvious link between crevasses and the calving of glacial ice chunks into the ocean. For one, crevasses decrease the strength of the ice sheet, since they break its continuity.

The surface of Jakobshavn Glacier in Greenland, is covered in crevasses, contributing to calving as the glacier meets the sea. Courtesy of William Colgan.
The surface of Jakobshavn Glacier in Greenland, is covered in crevasses, contributing to calving as the glacier meets the sea. Courtesy of William Colgan.

While it is clear that crevasses on the surface of the glacier are spots where blocks of ice may separate, interestingly crevasses on the underside of glaciers have a particular role in calving. They provide a site for an ice shelf, the portion of a glacier extending on the ocean, to snap upward. There is upward pressure on these ice shelves as the glacier is usually flowing down slope into the ocean and the buoyancy of the ice as it enters the water tends to push the shelf upwards. A crevasse on the underside of a glacier is an ideal spot for the glacier to snap upwards and break. The authors note that such research has supported quantitative modeling of glacial processes.

“Crevasses are the ultimate control on iceberg calving, and therefore the ice dynamic sea level rise contribution of glaciers and ice sheets,” Colgan said. “This makes understanding the crevasse lifecycle, especially formation, important to accurately projecting the future sea level rise contribution of glaciers and ice sheets.”

TinTin being rescued from a crevasse in the Himalayas, from Tintin in Tibet. Click here for the episode synopsis.
TinTin being rescued from a crevasse in the Himalayas, from Tintin in Tibet. Click here for the episode synopsis.

Crevasses are part of popular conceptions of glaciers. In one story in the Tintin comic series, a character Tharkey is nearly lost inside a crevasse when another character, Captain Haddock, releases the end of the rope to which he is tied; this episode forms part of efforts by Tintin and his associates to rescue a friend trapped in the Himalayas after a plane crash. Daring mountain climbers sometimes cross crevasses using ladders stretched across the crevasses’ mouths, and a special type of training is offered in crevasse rescue.  

As Colgan and his coauthors show, crevasses create not only dangers for fictional and real adventurers, but opportunities for scientists as well, who can even use them as a route into the inside of a glacier to conduct research, such as measuring the temperature of the ice.

Roundup: A New Documentary, Ice Worms, Timelapse Videos

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“Glacial Balance,” A New Documentary by Ethan Steinman on Climate Change

“Water and its sources have historically been the key factor in the establishment of cities, of civilizations. But we are at a critical point in the environment and mankind’s existence. . . GLACIAL BALANCE takes us to Colombia, Argentina, Chile, Bolivia and Ecuador, getting to know those who are the first to be affected by the melting glacial reserve.”

Read more, here

 

A picture of the Sholes Glacier
Photo By, Martin Bravenboer, Via Flicker

 

Glacier Ice Worms Thrive in the Coastal Ranges of the Pacific Northwest

Relying on alga from snowpack to survive, being vulnerable to death from exposure to sunlight, and only being able to move vertically, these worms face many challenges to survival.

Read more, here 

 

 

“Requiem of Ice” Amazing Timelapse Video Shows Melting of the Largest Glacier Cave in the Country

 “The cave systems have been mapped and surveyed since 2011 by Brent McGregor and Eddy Cartaya of the Oregon High Desert Grotto and in that time they have discovered more than a mile of caves and passages beneath the Sandy Glacier.”

A team from Uncage the Soul Productions shot “Requiem of Ice” in two caves named Pure Imagination and Snow Dragon, demonstrating the effect of the changing landscape.

Read more about this story, here

For more on the Sandy Glacier see, “Yes, Glaciers Melt, But Do You Know How?