Famous for being the largest and fastest-thinning glacier in Greenland—and creating the iceberg that sunk the Titanic, Greenland’s Jakobshavn Glacier has recently increased in size. For the past 20 years it has been melting, but during 2016-2017 it grew vertically about 100 feet, according to NASA’s Jet Propulsion Laboratory.
With so much news about global warming, it’s rare to hear about a glacier that’s expanding. It is crucial to note, though, that the glacier’s growth is not because climate change has suddenly stopped. Rather, it’s expansion can be attributed to cooler temperatures in the Atlantic Ocean. The cooling occurred in 2016 and is likely due to the natural variability of North Atlantic Oscillation.
The waters of the Atlantic will eventually warm again and could bring about renewed melting of the Jakobshavn Glacier—and higher sea levels.
“At first we didn’t believe it,” NASA’s Ala Khazendar said. “We had pretty much assumed that Jakobshavn would just keep going on as it had over the last 20 years.”
Kangerdlugssuaq Glacier is one of Greenland’s largest tidewater outlet glaciers. This type of glacier terminates in the sea, leading to frequent calving and releases of ice. Kangerdlugssuaq, which translates to “large fjord” in Greenlandic, is located on the southeastern coast of Greenland.
Ph.D. candidate Michalea King, who studies Greenland outlet glaciers at Ohio State University, created this week’s video of the week. The GIF documents glacial thinning in the 21st century on Kangerdlugssuaq Glacier.
The GIF’s x-axis shows the glacier’s change in elevation, which is measured in meters. The y-axis displays the glacier’s upstream distance, which is measured in kilometers. The upstream distance measures the distance of the glacier’s stream channel from the sea to the inner glacier. An upstream distance of 0 kilometers is located at the termination of the glacier, near the sea. And an upstream distance of 35 kilometers is located further inland, towards the inner part of the glacier.
The short video shows a decrease in glacial elevation over time. Years 2000 to 2005 are colored in blue, 2006 to 2010 are colored in green, and 2011 to 2016 are colored in yellow. The most recent recording, from 2017, is colored in orange.
Yellow and orange years reveal noticeable decreases in glacial elevation, meaning that the Kangerdlugssuaq Glacier is losing ice mass. The upstream distance, specifically from 5 to 15 kilometers, shows a greater loss of elevation than other upstream distances. This means that regions near the glacier’s termination, by the sea, are particularly vulnerable to ice mass loss. Decreasing ice mass over time is likely due to increased ice calving events.
The 21st century has been a time of persistent thinning for many Greenland glaciers – like here at Kangerdlugssuaq Glacier, one of the largest in the southeast region of the ice sheet. pic.twitter.com/ZytuuB5sCj
Following news of the arrival of a Manhattan-sized iceberg from a retreating glacier next to a village in Greenland, a recent paper published in the Journal of Geophysical Research has unveiled new research on how subglacial meltwater in Greenland is pumping nutrients and carbon from the deep sea to drive a boom of microorganisms in the upper layers. This effect fuels the ecosystems around it and impacts carbon cycling within the fjords and ocean close to the glaciers, further increasing the carbon uptake from the atmosphere.
Since 2002, Greenland has lost around 270 billion tons of ice per year. The glaciers and ice sheets of Greenland are key to the magnitude of future sea level rise, prompting scientists and researchers from around the globe to travel to the glacier-laced land to study and measure the physics of glacier melting and retreat. A team of researchers from Hokkaido University, led by Naoya Kanna and Shin Sugiyama, found a new perspective to understand the interactions of glaciers with ecosystems under a changing climate.
The researchers moved from geophysical measurements to geochemical measurements over time. They started to camp in the nearby village of Qaanaaq beginning in the summer of 2016, surveying the water temperature, salinity, ocean currents and other physical properties.
They then found an underwater nutrient and carbon transfer route that may explain these observations. Sugiyama describes the transfer as a “nutrient pump.”
At the bottom of the sea, due to the gravity and ocean currents, there are water flows from the fjord moving toward the glacier front. These flows carry a lot of descended nutrients and dissolved carbon. There is also subglacial freshwater discharge that is turbid because of the subglacial weathering. The two flows meet at the deep sea and create massive fluxes of sediments along the glacier fronts.
When the sediment-laden upwell water reaches the sea surface, it forms an opaque layer below the relatively fresher sea surface water. During the upwelling process, the mixture of subglacial discharge water and flows from the fjord pumps nutrients and carbon from the deep water to the upper layers.
The growth burst of the phytoplankton went unnoticed until recent years. Through their analysis of samples from supraglacial meltwater, proglacial stream discharge, fjord surface water, and plume surface water, the authors identify a distinct vertical distribution of nutrients and carbon along the centerline of the fjord. The data prove that the upwelling associated with the subglacial discharge has been pumping the nutrients and carbon from the deep water toward the surface, catalyzing the formation of phytoplankton blooms.
As the planet warms, glacier melting is increasing in Greenland. For its implication on their findings, Sugiyama said, ”Our study implies that nutrient supply to fjord surface water is enhanced by an increase in meltwater discharge under the warming climate. This results in higher primary production [of microorganisms]. On the other hand, turbid plume water also disturbs the production by limiting light availability in water.” He noted the team will continue their research to understand how these positive and negative impacts counterbalance.
The study not only showed a critical role of freshwater discharge in the primary productivity of microorganisms in front of the glaciers, but it also indicated that changes in glacier melt might impact the fjord ecosystems.
“Tidewater glacier front is a biological ‘hot spot.’ We see many birds and sea mammals near the front of Bowdoin Glacier. Change in the ecosystem is not clear at this moment, but we suspect such a highly productive ecosystem is sensitive to the warming Arctic climate,” Sugiyama said.
The ocean also acts as an immense carbon sink, which scientists need to explore. This finding may provide ideas for how carbon transfers within the marine ecosystem.
Sugiyama added, “A possible influence on the carbon cycle is more carbon storage in the ocean when primary production is enhanced by increasing amount of upwelling meltwater. Nevertheless, the plume process is not directly related to the intake of carbon from the atmosphere.”
Bowdoin Glacier is smaller than other rapidly retreating glaciers in Greenland, such as the Jakobshavn and Helheim glaciers. The team hopes to find out if the processes observed in Bowdoin Fjord resemble the situations in the fjords of larger glaciers.
For the 40 percent of the world’s population who live within 100 kilometers of the coastline, sea-level rise is more than just a mathematical calculation, it’s a survival challenge. Although scientists are confident about the impacts of accelerated glacier melting and ice flow on rising sea levels, projections for future ice loss remain at a fairly early stage. Developing better predictions for how glaciers melt and flow in the future remains a daunting task for glacier modelers.
A new analysis published in the Journal of Science argues that the “largest uncertainty” in ice sheet models used to predict future sea-level rise originates from our limited understanding of underwater processes at the ice-bed interface. These ice-bed processes beneath water involve interactions among the weight of the ice, water pressure, and the roughness of the bedrock. One of the major consequences, of these underwater interactions and a cause of sea-level rise is basal sliding, when the glacier slides over the bed as a result of meltwater between the ice and the bed acting as a lubricant.
To address the uncertainties of ice sheet models, the paper analyzed 140 wet-based glaciers in Greenland. Wet-based glaciers are known to have a thin layer of water between the ice and the rock bed. In contrast, glaciers found in the frigid Antarctic lack such a layer and are frozen to the end.
Scientific research on glaciers began in the early 18th century and developed more fully later on. Although glaciers seem static, their waning and waxing over time has long been recognized. Several theories have been proposed for this characteristic, including the Weertman formula, named after scientist Johannes Weertman. The Weertman formula states that the speed a glacier moves at its bed beneath the water is determined by both the friction and the amount of water surrounding the bed. Withstanding some bickering between Weertman and other scientists during the 1950s, the Weertman model has been widely accepted since then. An array of sea-level rise prediction models have built on this theory, with the latest study challenging the findings of the Weertman formula.
One of the two authors of the study, Leigh Stearns, a scientist at the Center for Remote Sensing of Ice Sheets from the University of Kansas, spoke to GlacierHub about her research on the topic. “We found that the commonly-used model for basal sliding (the Weertman model) does not apply to all 140 Greenland glaciers that we analyzed,” she said.
Instead, the researchers found that subglacial water pressure, the water pressure difference between the ice sheet end and the hard bed underwater, dominates the speed of glacier flow.
Intrigued by their initial observations of the 140 overlooked mountain glaciers in Greenland, Stearns and her university colleague C. J. van der Veen found the effect of friction on glacier sliding speed to be “virtually non-existent,” which implicitly defers the Weertman notion. As a result, they spent a long time trying to figure out what other factor correlated better with glacier speed, according to Stearns.
This analysis involved a closer study on the subglacial water pressure in Greenland. Stearns and van der Veen believe this aspect has been largely overlooked by the glaciological community to date. They started their observations by calculating water pressure from the thickness of the ice and then calculating the effective pressures under the water. Stearns and van der Veen paired these findings with the latest observational data about glacier flow speed and found that the two are highly related.
From yesterday's #IceBridge flight: The complex southern shear margin of Jakobshavn Isbræ in western Greenland, with an ambiguous grounded-to-floating transition. pic.twitter.com/T3DdpYlVjJ
However, Stearns also discussed the limitations of her study with GlacierHub. “We don’t understand all the mechanics for why the relationship between sliding velocity and effective pressure are so good, and why the relationship between sliding velocity and basal drag is so bad,” she said.
Recognizing these uncertainties, the paper focused on current models of sea-level rise, which are based on the strong relationship between sliding speed and the roughness of the bed.
“Hopefully it will allow them to constrain their sea-level rise prediction models better, so uncertainties of future ice sheet mass balance are reduced,” Stearns added.
The paper notes that it is “imperative for the ice sheet modeling community to explore the impact that this new relationship may have on sea-level rise prediction.” With that said, the consequences of the researchers’ new and challenging theory are still unfolding and could be highly significant.
GlacierHub contacted other scientists who built their work on the Weertman theory for feedback on Stearns and van der Veen’s latest findings, but these scientists did not respond to GlacierHub’s request for comment.
A recent study published in the Annals of Glaciology provides the first account of supraglacial lakes, which form on surfaces of glaciers in Greenland. The paper was a collaboration between University of Cambridge’s Alison Banwell and the University of Chicago’s Douglas MacAyeal and Grant Macdonald. Supraglacial lakes have been studied in detail in Antarctica, where they were found to accelerate glacier melting and thinning while triggering ice shelf instability and break-up upon formation. However, this recent study documents a different pattern in Greenland.
The research was conducted at Petermann Glacier’s floating tongue, a long and narrow sheet of ice protruding off the coastline. An ice tongue forms when a valley glacier advances rapidly out into the ocean. It has similar characteristics to an ice shelf, a feature more commonly found in Antarctica. Based on Landsat 8 satellite images from 2014 to 2016, the team was able to view the lakes over the area and discern when the lakes formed, their movement, and changes in surface extent across time.
In an interview with GlacierHub, MacAyeal explained, “Petermann Glacier has one of the few remaining ice tongues in Greenland and has lakes forming on it in each year. The glacier is of particular interest to the community due to its size and catchment, and the notable recent large calving events.”
The Petermann tongue underwent severe volume losses of up to 40 percent during two calving events in 2010 and 2012, for example. Fortunately, the grounded upper portion of the Petermann Glacier remains dynamically stable and showed little change in velocity or thickness.
“Glaciologists believe that supraglacial lakes store water and can become ‘dangerous’ to the continued existence of floating ice, such as the Petermann ice tongue, but more importantly to the ice shelves of Antarctica,” MacAyeal told GlacierHub. These supraglacial lakes usually form in the summer as melting is induced by an increase in air temperatures and solar radiation receipt. In the case of Greenland, the lakes at the Petermann Glacier typically fill in June, reaching their peak in July. At this time, the lakes are largest in area and volume, with their numbers at the maximum as well.
“The meltwater can fill cracks and cause them to extend through the ice. Also, when water flows into a depression and forms a lake, the lake is heavy and can cause the ice shelf to flex. Ice-shelf flexure can promote fracturing,” Macdonald further explained to GlacierHub. Fittingly, MacAyeal compares this to hydrofracking in the oil industry, except that this is a natural process when ice disintegrates as “heavy dense water fills crevasses and makes them crack farther open.”
As for the Petermann tongue, supraglacial lakes are less potent at inducing glacier thinning since lake drainage occurs relatively quickly. By July and August, even with the sustained high temperatures during the summer, total number, volume, and surface area of lakes were observed to have decreased. Drainage occurs in two ways: across the tongue surface and through the tongue. The former is enabled by the surface river system known as the Blue River which transports meltwater into the ocean across the tongue. The latter requires the process of rapid hydrofracking to occur, causing local lake drainage on the tongue. Overall, limited volume of meltwater storages on the tongue was noted, causing the research to lean toward the former mechanism.
Supraglacial lakes were under the spotlight when the formation of over 3,000 lakes caused the catastrophic disintegration of the Larsen B Ice Shelf in Antarctica in 2002. According to Grant, ice shelves are important as they shore up more than half of the Antarctic coast and several glaciers in Greenland. When this buttressing effect is removed the glaciers feeding the ice shelf accelerate. Without the ice shelves, more ice will enter the ocean at a faster rate, contributing to sea level rise.
Currently, the study indicates that supraglacial lakes cover less than 2.8 percent of the Petermann tongue, as compared to the 5.3 percent surface area prior to Larsen B’s collapse. However, there are warnings of higher density lakes with larger volumes that start developing earlier in the summer season due to higher air temperatures that could potentially destabilize ice shelves and tongues worldwide. “If we are to understand the future of ice shelves in a warming climate, we must understand supraglacial lakes,” Macdonald advised.
From Temblor: “Over the weekend, a M=4.1 earthquake on Greenland’s western coast caused a massive landslide, triggering a tsunami that inundated small settlements on the coast. At this stage, four people are feared to have died, nine others were injured, and 11 buildings were destroyed. Glacial earthquakes are a relatively new class of seismic event, and are often linked to the calving of large outlet glaciers.”
You can read more about the glacial earthquake in Greenland here.
Mural Restoration at Glacier National Park
From Hockaday Museum of Art: “Early visitors to Glacier Park Lodge were treated to architectural and visual grandeur inside the building that was almost as expansive as the surrounding landscape. The scenic panels covered hundreds of square feet and appeared in a 1939 Glacier Park Lodge inventory as ’51 watercolor panels.’ In September of 2012, Leanne Brown donated the murals to the Hockaday in memory of her grandparents, Leona and Robert Brown, who had saved and restored 15 of the murals.”
From AGU Publications: “Primary productivity in the Gulf of Alaska is limited by availability of the micronutrient iron (Fe). Identifying and quantifying the Fe sources to this region are therefore of fundamental ecological importance. Understanding the fundamental processes driving nutrient fluxes to surface waters in this region is made even more important by the fact that climate and global change are impacting many key processes, which could perturb the marine ecosystem in ways we do not understand.”
Read more about phytoplankton growth in the Gulf of Alaska here.
In 1576, Queen Elizabeth I paid the equivalent of half a million dollars for a unicorn horn, which she believed could neutralize poison. Of course, it wasn’t a unicorn horn at all, but a narwhal tusk, remarkable in its own right.
Today, over 440 years later, narwhals continue to surprise and attract attention. A recent paper in Biology Letters by Kristin Laidre et al. examined narwhal visits to glacial fronts in West Greenland.
“We don’t fully understand the relation between narwhals and glaciers,” professor Mads Heide-Jørgensen of the Greenland Institute of Natural Resources told GlacierHub. Laidre added, “Narwhals in places like the Canadian Arctic, for example, have limited access to glacial habitat. However, in Greenland, most narwhals are close to glaciers in summer because Greenland is so glaciated, and there are glaciers along the entire coastline.”
It has long been observed that narwhals visit glacial fronts in the summer and autumn, but it is unknown why they seek out this habitat. “Glaciers are productive regions,” commented Laidre. “They attract prey, there’s upwelling and nutrient cycling, and sometimes even osmotic shock to small invertebrates which attracts fish… We hope future studies will help us understand this, but we don’t know exactly why they go there.” Belugas, the “sister species” to the narwhal, also favor freshwater habitat in the summer, seeking out shallow water estuaries.
To begin answering this question, Laidre took a novel approach, forming an international, cross-disciplinary team that included scientists from the U.S., Denmark, and the U.K. “The idea was to get biologists and glaciologists to collaborate and share data in an interdisciplinary way,” Laidre said.
The team evaluated which glacial characteristics draw narwhals by collecting data from 15 satellite-tagged whales and following their movements through the fjords of Melville Bay in West Greenland. The narwhals demonstrated three preferences: they spent more time at glaciers that discharge a fresher, rather than siltier melt; they preferred slower-flowing glaciers, which are more stable and calve less; and they favored thicker glacial fronts, perhaps because they maximize access to freshwater.
Sea ice also provides important habitat for narwhals. “All narwhal populations winter, and some even summer, in dense sea ice concentrations,” said Heide-Jørgensen. In summer, narwhals spend time in the high Arctic where ice has receded, and in fall, the ocean freezes solid, pushing the narwhals away from shore, Laidre explained. “They swim away from the forming ice and move offshore, where they overwinter in dense ice cover with cracks so they can breathe. Narwhals are highly associated with sea ice, perhaps the most of all whales,” he said.
Heide-Jørgensen indicated that narwhals will seek out the sea ice when it decreases in coverage rather than wintering in open water. “Reduction of sea ice therefore implies a reduction in habitat, and this will again introduce a reduction in prey base or carrying capacity. In short, less sea ice means less narwhal habitat and eventually less narwhals,” he said.
Laidre agreed that “changes in sea ice and the marine ecosystem will likely be the most important factor” to the future of narwhals as climate changes. Since 1979, sea ice freeze-up has occurred almost a month later in Baffin Bay and Melville Bay, where this study took place, and glaciers, of course, are retreating. But far from being simple victims of global warming, narwhals can aid in the collection of data that can help mitigate climate change.
In 2005 and 2007, Laidre took advantage of narwhals’ capacity for deep dives and tendency to winter in sea ice, outfitting narwhals with temperature and depth sensors. Narwhals regularly dive over 1,700 meters to hunt bottom-dwellers like Greenland halibut, and 90 percent of the recorded dives reached the bottom. This method effectively turned narwhals into self-powered oceanographic instruments and allowed the researchers to collect wintertime data in Baffin Bay, the dearth of which had long been felt in climate records.
Perhaps, most importantly, the study proved that narwhals can constitute an effective ocean observation platform in remote areas where dense ice cover prevents regular instrument deployment. In this way, narwhals are even more magical than the unicorn Queen Elizabeth I imagined.
Roundup: Clues to Ötzi, Greenland Glaciers and Tibet
Tyrolean Iceman offers insights into Copper Age clothing.
From Nature: “The attire of the Tyrolean Iceman, a 5,300-year-old natural mummy from the Ötzal Italian Alps, provides a surviving example of ancient manufacturing technologies. Research into his garments has however, been limited by ambiguity surrounding their source species. Here we present a targeted enrichment and sequencing of full mitochondrial genomes sampled from his clothes and quiver, which elucidates the species of production for nine fragments. Results indicate that the majority of the samples originate from domestic ungulate species (cattle, sheep and goat), whose recovered haplogroups are now at high frequency in today’s domestic populations. Intriguingly, the hat and quiver samples were produced from wild species, brown bear and roe deer respectively. Combined, these results suggest that Copper Age populations made considered choices of clothing material from both the wild and domestic populations available to them.”
Learn more about the clothing of the Tyrolean Iceman here:
Early researchers of Greenland’s glaciers.
From Exploring Greenland: “Christopher J. Ries sheds light on the disparate goals of three diverse groups that created geological knowledge in post-World War II Greenland: the civilian scientists of the US Geological Survey Military Branch working in northern Greenland, an international team of geologists of the Danish East Greenland Expeditions led by Danish geologist Lauge Koch working in eastern Greenland, and geologists of the Danish Geological Survey of Greenland working in western Greenland. Ries argues that the interdisciplinary American group’s ultimate mission was to enhance the ability of military units to operate in Arctic terrains, while the two mono-disciplinary Danish-led teams attempted to balance academic interests in mapping and interpreting the structure of bedrock against more prosaic pursuit of profitable minerals.”
Read more about the early researchers of Greenland’s glaciers here:
Glacial melt of Tibetan Plateau exceeds USEPA guidelines.
From the Journal of Hydrology: “Global warming has resulted in rapid glacier retreat on the Tibetan Plateau, and the impacts of glacier melting on downstream ecosystems remain largely unknown. Minor and trace elements in stream water draining Dongkemadi Glacier were examined during the ablation season of 2013…Downstream increased concentrations and/or fluxes of some metals and metalloid (e.g. Cr, Cu and As) suggest potential environmental impacts. Discharge-normalized cation denudation rate (372 Σ∗meq+m−3) in the Dongkemadi Glacier basin is larger than those from alpine and polar glaciers, suggesting a stronger weathering of carbonate with greater abundance on the Tibetan Plateau in comparison to other mountain and polar glacial catchments. The maximum Fe concentration exceeds the USEPA guideline, and Al, Zn and Pb are close to or of the same order of magnitude as liminal values. This implies that the Tibetan Plateau may face a challenge of ecosystem health and environmental issue in a warming climate.”