Could Glacier Retreat Cause Seals to Wander?

Though populations of harbor seals – the captivating species seen in almost every zoo – are stable in other areas of the world, they are seeing declines in southeastern Alaska. These particular seals use icebergs calved from nearby glaciers as a place to rest and breed, but changes in ice availability are affecting these behaviors, crucial to their survival and reproduction.

Two separate studies, one by the National Park Service (NPS) and one by the Alaska Department of Fish and Game (ADFG), have independently found that seals may be changing their distribution and behavior to match the shifting locations of ice, as glaciers retreat.

Seals taking a break on top of a flat ice berg. (Courtesy of : Jamie Womble/National Park Service))
Seals taking a break on top of a flat iceberg. (Courtesy of: Jamie Womble/National Park Service)

Jamie Womble, leading the NPS research in Glacier Bay, is providing a new way of relating glacier ice extent and harbor seal territory, both in location and seasonality. Womble and her team aim to find the exact distribution and movements of these Alaskan harbor seals. Aerial tracking– flying above the ice and counting the seals–is a method that works effectively in the region. They also glue GPS transmitters to the seals, and track their movements on land-based monitors. These transmitters come off safely during the next summer’s molt, so they present only minimal risk to the animals.

Womble and her team found that “[d]espite extensive migration and movements of seals away from Glacier Bay during the post-breeding season, there was a high degree of inter-annual site fidelity (return rate) of seals to Glacier Bay the following pupping/breeding season.”

Harbor seal wearing GPS tracking device used in NPS research. (Courtesy of :National Park Service))
Harbor seal wearing GPS tracking device used in NPS research. (Courtesy of: National Park Service)

In addition to studying the distances which the seals traveled, Womble and her group also examined the patterns of seal movement in relation to the glacial ice. The team studied the ice distribution within John Hopkins Inlet, which they coordinated with aerial tracking data to examine the relationship between the ice extent and the harbor seals.

John Hopkins Inlet, the main area of research for Womble, is home to Johns Hopkins Glacier and Gilman Glacier which are among the few advancing glaciers in this region. Seals were found to congregate in areas with the highest percentage of ice.

Aerial image of harbor seals. (Courtesy of :National Park Service))
Aerial image of harbor seals. (Courtesy of: National Park Service)

“Tidewater glacier fjords in Alaska host some of the largest seasonal aggregations of harbor seals in Alaska,” Womble told GlacierHub in an interview. Many of these tidewater glaciers – glaciers that run into the sea and calve frequent icebergs – are thinning, and a few have begun retreating.

In particular, rapid retreat on the east side of Glacier Bay is leading to decreased seal pupping. During this critical season when the pups are newborn, mother seals and the weaning baby seals use flat icebergs to rest. “By 2008, no seals were pupping in Muir Inlet, and fewer than 200 seals were counted in McBride Inlet near the terminus of the McBride Glacier, the only remaining tidewater glacier in the East Arm of Glacier Bay,“ the NPS team stated in a recent report.

John Hopkins glacier, one of the few advancing glaciers in southeastern Alaska. (Courtesy of :Peter Makeyev/Flikr)
John Hopkins glacier, one of the few advancing glaciers in southeastern Alaska. (Courtesy of: Peter Makeyev/Flikr)

In a report, ADFG  emphasizes the importance of  studying  “…why, how, and when harbor seals use glacial habitat, and whether the rapid thinning and retreat of Alaskan glaciers associated with climate change could negatively affect harbor seals…” Their research documented similar instances of glacier thinning and retreat and they are also monitoring seal movement, as well as other topics, including seal diet, seal weight and bodily composition and disturbances by tour vessels. Though ADFG began their work in Glacier Bay, the same site as the other team, they moved their research to Tracy Arm Ford’s Terror Wilderness Area – more than 200 miles to the southeast.

The ADFG team has attached transmitters such as SPOT  to track the seals. These beam data on location, heart rate and other biological indicators up to satellites. To gather data, the researchers depend on the seals surfacing to breathe or rest, since the satellites cannot receive signals that are released underwater. The tracking for both research projects was most important during winter months, since researchers were interested in monitoring movement and feeding after the summer breeding season. (More tracking information, here)

Harbor seals, said to be awkward on land, use icebergs as a place of safety from predators. (Courtesy of :Jamie Womble/National Park Service))
Harbor seals, said to be awkward on land, use icebergs as a place of safety from predators. (Courtesy of: Jamie Womble/National Park Service)

ADFG also saw regular return rates for the sea populations which they studied. They hypothesized that they may travel to find food in the winter, but still return to Glacier Bay in the summer for the safety that icebergs provide from land-based predators. Icebergs are also important sites for the animals to haul out, since many beaches are entirely covered during high tides.

The ongoing research conducted both by Womble’s group and by the Alaska Department of Fish and Game show how recent changes in glaciers have already had large effects on the seal life cycle, specifically pupping. Continued monitoring of seal reproduction and movement in the context of glacier retreat will allow for predictions of the future of this important species in a critical section of its range.

Roundup: Icebergs, Mobile Toxins, Festive Algae

Iceberg Ahead! A New Study Finds Way to Avert Disaster

“When performing offshore operations in the Arctic, there are several challenges. One of those challenges is the threat of icebergs on offshore structures and vessels. Icebergs can exert extremely high loads on vessels, offshore platforms, and seabed installations.”

Arctic iceberg photographed aboard the NOAA Ship Fairweather. (Courtesy of :NOAA's National Ocean Service /Flikr)
Arctic iceberg photographed aboard the NOAA Ship Fairweather (Courtesy of :NOAA’s National Ocean Service
/Flikr
)

Find out how the team is proposing safer Arctic travels.

 

 Glaciers Retreat Toxic Metals Are on the Move in Tibet

“In mountain ecosystems, the most important natural source of trace metals is from the weathering of parent materials. However, in recent decades, the metals in mountain regions are mainly from anthropogenic sources including mining, refinement, and fuel combustion. Considering the toxicity of trace metals, it is necessary to investigate and evaluate their mobility and eco-risk in mountain ecosystems.”

Cadmium, one of the elements of concern found in Tibetan soil. (Courtesy of :Images of Chemical Elements/Wikimedia))
Cadmium, one of the elements of concern found in Tibetan soil. (Courtesy of :Images of Chemical Elements/Wikimedia))

Learn more about the possibly toxic soil exposed as glaciers retreat.

 

With Red and Green Snow, Algae Just Misses Christmas Season

“We demonstrate that green and red snow clearly vary in their physico-chemical environment, their microbial community composition and their metabolic profiles. For the algae this likely reflects both different stages of their life cycles and their adaptation strategies. ”

Red and green algae plumes atop Californian water fields. (Courtesy of :Caribb /Flikr)
Red and green algae plumes atop Californian water fields. (Courtesy of:aribb
/Flikr
)

Read more about the colorful algae and what it means for soil quality.

 

If You Can’t Handle the Heat – Retreat

Zachariæ Isstrøm, a large glacier in the northeast coast of Greenland, is in a state of accelerated retreat after it detached from an important sill. This shift has caused great instability for the glacier, according to a new study from Science Magazine.

Recognizing 0.5 meters of possible sea level rise held within Zachariæ, and its acceleration expected to continue, the authors point to an increased likelihood of sea level rise coming from this area in the next 20 or 30 years. This study is noteworthy since Zachariæ is found far north, close to 79 degrees N. The Greenland glaciers which have been highlighted for their fast retreats to date are found further south. 

Zachariæ Isstrøm retreat (2003-15) captured by NASA/USGS Landsat satellite (Courtesy of :NASA/USGS)
Zachariæ Isstrøm retreat (2003-15) captured by NASA/USGS Landsat satellite (Courtesy of :NASA/USGS)

Jeremie Mouginot from the University of California, Irvine and his coauthors looked specifically at the effects of warming ocean and air temperatures on the melting and discharge dynamics of the glacier. (More Greenland work from the UCI team can be found here.)

The precise measurements of the ice discharge data were made possible by NASA, who provided funds and much of the data and equipment. 

Zachariae Isstrom and Nioghalvfjerdsfjorden - a similar glacier currently seeing less drastic changes (Courtesy of :NASA/USGS)
Zachariae Isstrom and Nioghalvfjerdsfjorden – a similar glacier currently seeing less drastic changes (Courtesy of :NASA/USGS)

The researchers observed a 50% increase in the retreating speed since 2000. There was also a doubling of ice thinning. On the ice shelf, this process was extensive enough to be measured by satellites. Data showed Zachariæ in a stable state up until 2003 when a large piece broke off. Since that breaking point Zachariæ retreated at a steady state until 2013-14 when the retreat accelerated. It is now retreating at a rate of 125 meters per year and losing 5 gigatons of mass yearly.

The increased mass loss is attributed by the authors to a combination of warming air and ocean temperatures. These changes lead to increased ice loss by way of calving, as opposed to changes in the accumulation of mass through precipitation. 

Ocean temperatures play an important role in glacier retreat; the authors argue that the nearly 1 degree C increase in ocean temperatures near the glacier is largely responsible for triggering the enhanced retreat.

Warming air temperatures lead to an increase in ice thinning which affects the placement of the grounding line below the surface – an important transition area where the glacier begins floating.  As the grounding line retreats there is increased surface area of the glacier exposed to the melting from below. Zachariæ began to calve so rapidly at the grounding line in 2014 that the remaining ice shelf was “95% smaller than in 2002” according to the researcher’s Landsat optical imagery data.

The authors did speak of another glacier in the Northeast of Greenland that is also experiencing accelerations-Nioghalvfjerdsfjorden Glacier (NG). Though the overall changes on NG were not as rapid as Zachariæ, the authors suggest that NG will become more vulnerable in the future.

A tidewater glacier, Margerie Glacier, in Glacier Bay Alaska.(Courtesy of :LH Wong/Flikr)
A tidewater glacier, Margerie Glacier, in Glacier Bay Alaska.(Courtesy of :LH Wong/Flikr)

“Not long ago, we wondered about the effect on sea levels if Earth’s major glaciers were to start retreating,” said one of the authors, Eric Rignot. “We no longer need to wonder; for a couple of decades now, we’ve been able to directly observe the results of climate warming on polar glaciers. The changes are staggering and are now affecting the four corners of Greenland.”

Isstrøm, a Danish phrase that translates as ice stream, seems to take on a poetic meaning when one thinks of the drastic amount of ice now “streaming” from the glacier.

As Zachariæ transitions into a tidewater glacier, it can be expected to calve more icebergs and become more vulnerable to increases in ocean temperatures. With other glaciers in this area retreating quickly Greenland will be an important region to watch in the coming decades, the authors concluded.

Here is a quick video illustrating how the position of the grounding line can accelerate retreat of a glacier by increasing the area exposed to currents.

 

Do Village Traditions Trump Adaptation?

The village of Manang, high in the Himalayas in Nepal, is using economic diversification to stave off the effects of climate change, but will soon reach a point where more adaptation is needed, Katie Konchar and her coauthors warned in a new study in the Journal of Ethnobiology. The team used semi-structured interviews and innovative photography techniques to gain insight on current village perceptions and adaptations.

Annapurna Base Camp (Courtesy of:Matt Zimmerman/Flikr, please contact the photographer before using)
Annapurna Base Camp (Courtesy of:Matt Zimmerman/Flickr, please contact the photographer before using)

Nearly three-quarters of respondents perceived increased temperatures especially during the winter months – consistent with the regional instrumental observations. The uniquely structured interview style allowed for more detailed responses. For example, one villager stated “[b]efore in winter water was ice; now we can easily wash our face in winter.” The authors argue that the unique ecological knowledge of locals is vital to the development of placed based adaptation plans.

Villagers offered a variety of explanations for climate change: CO2 concentrations, pollution, or development, while others, usually the elders, believed it was due to actions of gods. One of the participants who mentioned CO2 was part of an outreach program by the Annapurna Conservation Area to educate the villagers on the effects of climate change.

Entrance gate in Manang (Courtesy of: Greg Willis/Flikr, please contact the photographer before using)
Entrance gate in Manang (Courtesy of: Greg Willis/Flickr, please contact the photographer before using)

The village relies heavily on glacier meltwater for its traditional agriculture economy, since it is in the rain shadow of one of the tallest mountains in the world, Annapurna, so that seasonal rainfall is insufficient for raising crops. This region has seen a change in the predictability of rain, leading to an abnormally varied growing season. Though the increased temperatures and varied rain make it difficult to maintain their traditional agriculture, the participants pointed to an increase in cash crop such as vegetables as one of the most important changes in their livelihoods. The authors state that the transition from traditional crops–chiefly grains and potatoes, adapted to cold climates–to milder climate cash crops is an important step to adapting to climate change. Tourism has also increased ,due to improved transportation in the area which allows foreigners to trek into the area, helping to diversify the economy even further.

The authors point to the diversification as an important adaptation, but they also warn of future dangers in an even warmer climate. Glacier retreat could lead to decreased water availability, less attractive scenery to attract tourists, increased glacial lake flooding and an unreliable traditional agricultural calendar. The authors argue that the traditional practices, reinforced by spiritual lamas, need to adapt alongside the economic changes already being seen.

Prayer stones in front of Gangapurna glacier (Courtesy of :Vera & Jean-Christophe/Flikr, please contact the photographer before using)
Prayer stones in front of Gangapurna glacier (Courtesy of :Vera & Jean-Christophe/Flickr, please contact the photographer before using)

The interviews in this study were validated in part by a unique technique of repeat photography-pictures taken during the week of interviews were compared to historical pictures to see climatic changes. These “… photographs illustrate the changes in woody vegetation coverage surrounding the village, the increase in the size of Gangapurna Lake [due to increased glacial melt], and the rapid retreat of the Gangapurna Glacier highlighted during interviews.”

Though the authors applaud the villager’s added economic resilience of planting more cash crops and increased focus on tourism, they say there will come a point when the agricultural society will not be able to live off of the glacier meltwater or rain seasons that they traditionally depend on, and need to start adapting at an even quicker pace. “Continued development of relevant, place-based adaptations to rapid Himalayan climate change depends on local peoples’ ability to understand the potential impacts of climate change and to adjust within complex, traditional socio-ecological systems.”

Roundup: Gloomy Glaciologist, Icy Blasts, and New Models

Glaciologist Causes Chills with Not So Icy Predictions

“How does being the one to look at the grim facts of climate change most intimately, day in and day out, affect a person? Is Box representative of all of the scientists most directly involved in this defining issue of the new century? How are they being affected by the burden of their chosen work in the face of changes to the earth that could render it a different planet?”

(Photo:NASA's Goddard Space Flight Center/Jefferson Beck, please contact the photographer before using)
A man collects meltwater temperatures in Greenland, where Box does most of his research. (Photo:NASA’s Goddard Space Flight Center/Jefferson Beck, please contact the photographer before using)

Read more about the man who, for better or for worse, set off climate alarm bells.

 

Could Climate Change Cause More Icy Blasts?

“The degree of activity of the volcano provides a semiquantitative indication concerning the probability of future eruptive activity, but changes in snow and ice as induced by climate change and/or volcanic activity can superimpose fast or slow trends with respect to hazards and risks related to volcanoe-ice interactions…”

11792310944_a1b0d0df04_k

The paper speaks of the particular risks the eruption of Mt. St Helens caused. (Photo: Eric Prado/Flikr, please contact the photographer before using)

Read more about the risks of volcano-ice interactions and how those risks might effect society.

High Resolution Model Accurately Recreates Glacier Variability

“Altogether, the model compares well with observations and offers possibilities for studying glacier climatic mass balance on Svalbard both historically as well as based on climate projections.”

Glaicer calving in Svalbard. (Photo:Gary Bembridge/Flikr, please contact the photographer before using)
Glaicer calving in Svalbard. (Photo:Gary Bembridge/Flikr, please contact the photographer before using)

Read more about how the researchers were able to get their models so accurate.

 

Tibet’s Melting Glaciers; The World’s Leaky Roof

Tibet is often referred to as the roof of the world, since it is the world’s largest and highest plateau. The lead-up to the 21st Conference of the Parties in Paris, or COP21, created a push to make Tibet a central part of the discussions, even though it does not have direct representation there. Though some countries, such as Peru and Nepal, incorporate minority peoples into their national delegations at COP21, China has not included Tibetan representation in their delegation. The Climate Action for the Roof of the World campaign is arguing that the COP21 agreement cannot be accomplished, and thus the house cannot be saved, without direct consideration of Tibet.

Tibet is not only the highest plateau, with an average elevation of more than 4000 meters above sea level, it is also known as the Third Pole of the world. With 46,000 glaciers, it is the world’s largest concentration of ice after the Arctic region and Antarctica, at the North and South Poles. Two-thirds of those glaciers may be gone by 2050 if the current rate of retreat is sustained.

In a press release on the campaign’s website there is a powerful quote from the Dalai Lama: “This blue planet is our only home and Tibet is its roof. As vital as the Arctic and Antarctic, it is the ThirdPole…[t]he Tibetan Plateau needs to be protected, not just for Tibetans but for the environmental health and sustainability of the entire world.” The goal of the campaign is to show the world how environmentally critical and fragile Tibet is.

NASA photo of Himalayan Mountains and Tibetan Plateau (Courtesy of:NASA/Wikimedia Commons)
NASA photo of Himalayan Mountains and Tibetan Plateau (Courtesy of:NASA/Wikimedia Commons)

The Roof of the World campaign highlights a few key points that they feel make the Tibetan plateau crucial to the world’s climate and therefore central to COP21; the glaciers provide water for 1.3 billion people in the surrounding area, it influences the region’s monsoons, and there has been a link made connecting thinning Tibetan snow cover with heat waves in Europe.

The campaigners believe that if the Tibetan ecosystem is to be preserved, the Chinese government needs to enforce their Environmental Protection Law more vigorously and the global community needs to engage in robust climate action. The campaign points out a number of  critical areas that need to be addressed in a worldwide: retreating glaciers, permafrost melting, the lack of snow accumulation since the 1950s, and threats from deforestation, mining, and dams as.

The campaign could be seen as a form of “clicktivism” since it is being introduced to the world by way of social media. There is an online photo challenge where people post photos of themselves with their hands above their heads, forming a “roof,” to show their solidarity with the campaign. There are even pictures of the Dalai Lama getting involved, posting his own roof photo. The Dalai Lama has been actively pursuing climate change action since 2011, so it is notable that this is the campaign he has chosen to support. There is also a Thunderclap organization that attempts to amplify users’ messages through way of active social participation that the Roof of the World campaign has used to spread it’s message. The website itself, though, is full of informative guides to help update those who wish to learn more about Tibet and seems to actively push for action beyond the social media campaign.

GlacierHub’s managing editor, Ben Orlove, who is currently in Paris for the COP, met a colleague there who is familiar with Tibet. This source, whose anonymity we are maintaining, states “Tibet.net is directly funded by the Tibetan exile government [in Dharamsala, India]. The website is from Tibet Policy Institute.” The source added that it serves as a lobby group, and that a number of academics find that Tibet Policy Institute is at times unbalanced and extreme with the information on Tibet’s climate and environment. The source adds, “Tibet Policy Institute never claimed to be in the forefront of research on original Tibetan research and their job is to lobby and they are good at making information digestible and engaging for the public.”

The COP21 will begin December 7 and will bring together world leaders with the goal of a global climate agreement. Tibet is not on the agenda, but the Roof of the World Campaign hopes to make Tibet more of a focal point in the coming weeks.

 

 

Photo Friday: Kazakhs of the Altai Mountains

The Altai Mountains in Central Asia, located where Russia, China, Mongolia and Kazakhstan meet, is home to a diverse and intriguing population. Altai is Turkic-Mongolian for golden and this land of vast beauty has several glaciers, including Tsambagarav Glacier pictured below. One particularly interesting population in this region is the Mongolian Kazakh, who tame golden eagles to hunt from the heights of these formidable mountains. Enjoy these photos of Mongolian Kazakhs spending time with family, playing sports and eagle hunting.

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Peak Water Looms in Central Asia

Satellite image of Tien Shan mountain range
Satellite image of Tien Shan mountain range (Courtesy of WikiMedia Commons)

Glacier mass loss is threatening community livelihoods in Chon Kemin valley, in Central Asia. People in the region “strongly [depend] on glacial melt water for fresh water supply, irrigation and hydropower production…” say Annina Sorg and her coauthors of a paper studying the increased glacial melt in this area and its effect on peak water levels. The study area is of considerable importance, since it contains a number of agricultural villages, and provides water for Bishkek, the capital of Kyrgyzstan. Originating in Kyrgyzstan and flowing into Kazakhstan, the Chon Kemin is an international river. 

This Central Asian mountain region is located in the Kyrgyz portion of the Tien Shan Mountains very close to the border of Kazakhstan. The researchers used both old and new methodology to project glacier mass loss. They relied on longer than usual time series of past temperature, snow cover and precipitation data from the area, but they “…also downscaled data from phase five of the Climate Model Intercomparison Project CMIP5…”. This downscaling is very unusual for mountainous Central Asia, allowing them to obtain data at a finer spatial resolution than previous research. The unusual data collection was needed to compensate for the decline in weather station data after the fall of the Soviet Union. Experiments were run with the Glacier Evolution Runoff Model (GERM) so that the researchers were able to record “[g]lacier mass balance, basin evaporation and runoff.”

The authors were able to include many inputs into their parameterizations to obtain what they confidently felt was a realistic result. They calibrated their models to have four future climate scenarios, “…dry-cold, dry-warm, wet-cold and wet-warm future climates…,” which gave a wide breadth of possible glacial lifetimes; in this way, they calculated a range of possible dates for the timing of peak water–the point in time when river flow will be at its highest level.  Glacier retreat first leads to an increase of flow, as water stored as glacier ice melts at a higher rate than previously; however, it later leads to a decrease in flow, when the meltwater from the much-reduced glaciers is lower than it had been earlier.

Tien Shan Mountains
Flying Over the Tien Shan Mountains (Courtesy of WikiMedia Commons)

The results showed that there are longer melt season in the Chon Kemin valleys, influenced by warming temperatures and increasing precipitation. The study showed that increased temperatures did not cause a substantial increase in winter runoff, but winter precipitation did increase. This increased snowfall led to even greater, and longer, snow melts in the warmer seasons.

They also found large differences in the scenarios that they ran. In the “glacier friendly” models, the glaciers were able to sustain themselves to roughly less than half their 1955 mass until 2099. In the warmer scenarios, glaciers were gone by 2080. The authors argue that these findings demonstrate the association between a warming climate and increased speed of glacier mass loss. The researchers paid particular attention to the variability of evaporation and how that may play into future glacier mass loss.

 

The authors argue that peak water is coming relatively soon in this region, either as early as 2020, or near the end of the century, depending on the specific climate scenario. Regardless, peak water levels will be detrimental to the people of the Chon Kemin Valley; signifying the need for further water management programs.

View of Tien Shan mountains in Kyrgyzstan
View of Tien Shan Mountains in Kyrgyzstan (Courtesy of Christoph Schaaf)

The authors offer the solutions of using nearby reservoirs, using less water intensive crops and restructuing irrigation. They allude to the tensions caused by the international boundaries in this area, drawn in Soviet times,  but remain hopeful that this region can come together to solve its impending water shortage. They briefly discuss the region-wide Chu Talas basin agreement as a possible buffer to those political complications.

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.