The last photo highlights “The Man”, an unstable mountainside located in the region. If this mountainside were to fall into the fjord, it could create a tidal surge of up to 80 meters high. Fortunately, Norwegian researchers at The Norwegian Water Resources and Energy Directorate are constantly monitoring the mountainside.
Fjords are long, narrow inlets of the sea, situated between mountainous coastline on either side. Fjord formation occurs when significant glacial retreat reaches bedrock level. The glacial retreat then leads to land erosion and the creation of a U-shaped valley, which fills with seawater, resulting in unique geological features such as Geirangerfjord.
This post is the second in a series of posts about firsthand experiences visiting Norwegian glaciers, famous fjords, and well-known hiking destinations. Check back to GlacierHub in upcoming weeks to read more about my travels in Norway.
As global warming increases, cold regions like the Arctic continue to experience great shifts in climate and environment. The effects of these shifts are closely observed in human populations, but how are different species impacted? A recent study examined white whales in Svalbard, Norway, and the climate change effects on their behavior and diet. Researchers looked at how reduced sea-ice formation and melting tidal glacierfronts influence the changes in habitat and movement patterns for this species.
White Whale Background and Observations
White whales, also known as beluga whales, can be found in the circumpolar Arctic. They’re known for their distinct white color and are one of the smallest whale species in the world. They are sometimes referred to as “sea canaries” for their high-pitched calls. With an estimated 150,000 individuals globally, they are listed on the IUCN Red List of Threatened Species. Some local populationssuch as those located in Cook Inlet, Alaska, are consideredcritically endangered.
These whales remain off the Svalbard coasts year-round. They live in sea-ice fjords and tidal glacier-front habitats. The fjords are sheltered from open-water predators, human activity, and extreme weather, making them particularly ideal for juvenile mammals. Tidal glacier-fronts are prime foraging areas for the whales. These regions have fresh water ideal for polar cod and capelin, two fish that make up a large part of white whale diet.
White whales migrate seasonally, some travelling 10s of kms, others as far as several hundred. During the warm summer season, seaice in the fjords melts, providing an opportunity for the whales to move and feed in this region. Sea ice formation in the winter pushes the whales out toward the glacier-front habitats, where they spend most of their time during the colder season.
Methodology and Sampling
Increased warming is expected to negatively influence the environmental composition of this region. Svalbard has the greatest decrease in seasonal sea-ice cover in the circumpolar Arctic region. Rapid increase of air and sea water temperatures over the last two decades are the major contributing factors to this change. According to researchers, glacier-front melting and the associated reduction of foraging habitat could lead to changes in diet. Less sea-ice formation in fjords and warmer seasons could also affect biodiversity in these habitats. Could this mean white whales will need to migrate elsewhere for feeding during warmer seasons?
Researchers in this study compared habitat and movement changes of white whales, before and after major warming induced changes in the environment. They believed these changes began in 2006, so the two study periods were 1995-2001 and 2013-2016.
Fortunately for the researchers, satellite data from earlier years was available. They used satellite tracking to take measurements of whale movement patterns for the later period, and were then able to compare movement patterns for both periods. To track movement, white whale groups were live-captured using a nylon net and then tagged.
GlacierHub interviewed Kit M. Kovacs, one of the study’s authors and a senior research scientist at the Norwegian Polar Institute. Kovacs explained that choice of methods reflected concerns for animal welfare as well as data gathering. Groups without calves were netted, to prevent possible injury to young whales, she said. A total of 38 adult individuals were sampled for the study, 34 of them being male. Kovacs also explained that the females travel with their young, while adult males tend to travel in all-male groups, which would explain the sampling bias.
Research Findings and White Whale Resiliency
Results showed that during the later tracking period, the whales continued to remain close to the Svalbard coast. Scientists found this behavior to be striking, particularly when looking at populations in other areas that move long distances. The whales remain close to Spitsbergen, one of the largest islands in Svalbard. They move from the west coast fjords in the summertoward the east coast in the winter. The greatest distance of movement occurred when individuals were forced off the coast by the winter formation of landfast sea ice.
Some changes in habitat were observed. Whales were found to spend much time in glacier-front habitats for both periods, although they now spend more time out in the fjords. Less sea ice formation in the fjords has allowed for an influx of fish species that prefer the warmer waters. Arctic fish, particularly polar cod, have declined in numbers in this habitat, and are being replaced by Atlantic cod, haddock and herring. This new fish composition could be attracting the whales to fjords during the warm season.
Kovacs explained how a change in diet could affect the whales. “White whales use a pretty broad array of food types across their range, so it is unlikely to be a big deal for them to switch to new fish types. They might have to eat more, if the new fishes have a lower fat content, just to keep the same energy intake. As long as enough are available, it should not change their annual intake,” she said.
The white whales’ ability to consume a variety of food resources proves to be beneficial to the species. This helps them build resilience against some of the extreme effects of warming. The beluga may be able to adapt to an environment with less ice than in the past due to this dietary flexibility. Other species may not be so fortunate.
Between 2003 and 2010, the Greenland Ice Sheet and its associated glaciers experienced a mean annual mass loss of 186 Gt, double the rate between 1983 and 2003. Though this mass loss has been linked to global sea-level rise through meltwater discharge, heightened glacial runoff has also been hypothesized to have another important effect: increasing marine primary productivity through nutrient fertilization. This hypothesis was the focus of a recent study published in Nature Communications, which reports that the upwelling of nitrate-rich deep seawater driven by subglacial discharge— not the meltwater itself— is likely the main driver of the increased productivity.
This question about the impact of heightened glacial runoff is important both for academic research on marine ecosystems and for assessing the future of oceans to serve as carbon sinks. The photosynthesis represented by primary productivity is one of the key mechanisms through which carbon dioxide dissolved in seawater can be captured and retained in the oceans.
During the spring, marine primary productivity off the coast of Greenland increases as phytoplankton bloom. Then, in the summer, productivity usually diminishes. Recently, however, there have been summer phytoplankton blooms accounting for up to half of annual primary productivity. The goal of the study was to examine these changes to summer productivity and see how they relate to nutrient availability during the meltwater season.
The researchers first assessed which nutrient deficiency limits summer primary productivity off of Greenland. In most parts of the high-latitude Atlantic, summer primary productivity is limited by iron or nitrate deficiencies. However, in Greenland, few studies had previously examined the nutrient limits to phytoplankton blooms.
The researchers found that iron values were the most positive near the coasts, while offshore values were close to zero. On the other hand, nitrate values were deficient near the coasts and offshore. These results indicate that iron may help trigger the summer blooms while also inhibiting the drawdown of nitrate by plankton, leading the researchers to conclude that the availability of nitrate is likely the constraint on summer primary productivity.
Is heightened glacial runoff supplying more iron and nitrate, contributing to the summer phytoplankton blooms? Iron concentrations from glacial runoff were comparatively low, unlikely to trigger the blooms given the already iron-rich waters, the authors concluded. Furthermore, in Greenland, glacial runoff supplying iron can have a negative impact on primary production. It has this effect by reducing the availability of other nutrients and by creating cloudy sediment plumes from glacial flour composed of fine-grained rock particles created by glaciers grinding over underlying bedrock. These cloudy plumes limit light availability, says lead author Mark Hopwood, who spoke with GlacierHub about the paper. In contrast, he said, nitrate concentrations were found to be even lower than iron ones, only enough to have a very small effect on phytoplankton blooms.
While the meltwater from glacial runoff is unlikely to be the trigger of the summer plankton blooms off Greenland, the researchers determined marine-terminating glaciers to represent another aspect of glacial discharge.
Unlike their land-terminating counterparts, marine-terminating glaciers discharge meltwater through sub-glacial plumes. This discharge, once injected into the water at the glacial grounding line, entraps nutrient-rich deep seawater in a rising plume. This upwelling, if it occurs at the right depth, takes nitrate-rich waters to the photic zone where light is sufficient for photosynthesis, driving the phytoplankton blooms.
The researchers found four scenarios through which plume upwelling affects nutrient delivery near marine-terminating glaciers, with glacial grounding line depth the primary influence on the efficacy of this delivery. Under the first scenario, a nutrient-rich plume is generated by sub-glacial discharge. However, the glacier is too deep, and the plume is unable to reach the photic zone. In the second scenario, the glacier is in the optimum depth zone, and the nutrient-rich deep sea water is upwelled to the photic zone, enhancing the phytoplankton bloom. In the third scenario, the grounding line depth shallows because of glacial retreat. This shallowing limits the amount of seawater entrapped by the sub-glacial discharge. The seawater that is entrapped lacks the nutrients of deeper waters, thereby lessening the positive effects of the upwelling on phytoplankton blooms. In the final scenario, the glacier has retreated inland and no longer ends in the ocean, so no upwelling is generated.
After delineating these four scenarios, the researchers next simulated the plume upwelling effect to find the optimum conditions for peak nitrate flux to be upwelled to the photic zone. According to Hopwood, each fjord-glacier system in Greenland has unique physical characteristics, such as fjord depth and annual discharge volume.
This means that the optimum conditions for each system varies regionally. As a general rule of thumb, shallow glacier grounding line depths below 100 m will likely lead to low productivity, while grounding line depths between 400 and 600 m will likely be linked with high productivity, according to Hopwood. Other factors also affect summer marine productivity including turbidity and the depth of the photic zone. However, the plume upwelling of nutrients appears to be the dominant factor.
The future of marine productivity off Greenland under climate change will be determined by glacier grounding line depths, which may remain as they currently are or migrate into the optimum zone for subglacial discharge, triggering the upwelling of nitrate nutrients. Shallow glacier grounding line systems are likely to have already experienced peak nitrate supplies, while the peak for deeper systems will likely occur in the future if current retreats continue. For the 243 Greenland glaciers that have been mapped for bed topography, 55 percent will retreat onto land in the future, reducing the ice sheet-to-ocean nutrient fluxes driving summertime phytoplankton blooms.
What happens to the plume upwelling of nutrients in Greenland ultimately depends on climate change and subsequent glacier retreats. One subject for future study that could help improve understanding of marine productivity is the influence of icebergs, says Hopwood. The largest icebergs usually extend far below the ocean surface, hypothetically allowing them to “act as miniature nutrient ‘pumps’ as they melt,” Hopwood told GlacierHub. This is similar to what occurs with glaciers on a larger scale. Yet icebergs are more difficult to study and will require interdisciplinary work between both physicists and chemists to examine how icebergs affect the water column and phytoplankton.
Taken together, this research on the effects of different kinds of glaciers on phytoplankton blooms is key to a better understanding of marine ecosystems, helping scientists to assess the ability of the oceans to serve as sinks for the carbon dioxide that we humans continue to release.
From Global Change Biology: “Accelerated mass loss from the Greenland ice sheet leads to glacier retreat and an increasing input of glacial meltwater to the fjords and coastal waters around Greenland. These high latitude ecosystems are highly productive and sustain important fisheries, yet it remains uncertain how they will respond to future changes in the Arctic cryosphere. Here we show that marine-terminating glaciers play a crucial role in sustaining high productivity of the fjord ecosystems.”
From Wiley Interdisciplinary Reviews: “Since the late 1990s, most closed lakes in the interior TP expanded and deepened dramatically, in sharp contrast with lake shrinkage in the southern TP. Although some evidence shows that glacier melting and permafrost thawing within some lakes may influence lake level changes, they can not explain the overall lake expansion, especially for lakes without glacier supply. More and more evidence from lake water balance modeling indicated that the overall lake expansion across the interior TP may be mainly attributed to a significant increase in precipitation and associated runoff.”
Scott Pruit (EPA) Fires Shots at Glacier Enthusiasts
From The Onion: “Oh my god, what is it with you people? It’s like you’re obsessed. It’s all you ever talk about: Wah, wah, wah, the glaciers are melting! We just can’t live without our precious glaciers! I hear it so often I’m seriously starting to wonder if maybe there isn’t something else going on here. So tell me, are you guys totally in love with glaciers, or what?”
From Huffpost Green: “A new study published in the journal Nature is drawing attention to the effect of warming water on the world’s largest ice mass, Totten Glacier in East Antarctica. Melting of the glacier, which has an ice catchment area bigger than California, could lift oceans at least two meters (6.56 feet). According to researchers who mapped the shape of the ice sheet as well as the thickness of rocks and sediments beneath it to examine the historical characteristic of erosion of Totten’s advances and retreats, unabated climate change could cause the glacier to enter an irreversible and rapid retreat within the next century.”
From Zee Media Bureau: “New Delhi: NASA’s IceBridge, an airborne survey of polar ice, recently captured this stunning view of fjord of Violin Glacier, with Nord Glacier at the upper left corner. IceBridge took this image on May 16, 2016 as the aircraft crossed Greenland to fly central glacier flowlines in the east-central region of the country. This year marks IceBridge’s eighth spring campaign of science flights over Arctic sea and land.”