GlacierHub’s Video of the Week features footage of a flowing piedmont glacier on Ellesmere Island, which lies in the Canadian Arctic territory of Nunavut. The animated images, posted on Twitter by glaciologist Jakub Małecki, give the impression of a glacier in graceful motion.
Much of Ellesmere Island is covered by glaciers and ice sheets. Research published in 2016 in the journal Geophysical Research Lettersfound that ice mass on the island—and across the Canadian Arctic Archipelago—has decreased dramatically in recent years.
Melting land ice, such as from Ellesmere Island’s glaciers, contributes to sea level rise, which threatens some of the world’s most populated and economically valuable cities.
Christopher Harig, an author on the 2016 study, told GlacierHub: “Worldwide, on the order of 500 million people could be directly impacted by rising sea level by the end of this century. The human impact is combined with a large financial impact as well. So regardless of where people live, I think the impacts of ice loss and sea level rise will be easily seen in the future.”
Environments with the power to unlock the secrets of other worlds have been found several hundred meters beneath the ice of the Canadian Arctic. A joint study published last month in Science Advances predicted the presence of two hypersaline subglacial lakes on either side of the east-west ice divide of the Devon Ice Cap, an ice cap located in Nunavut, Canada, known for its rugged terrain of both mountain ridges and bedrock troughs. These are not only the first subglacial lakes to be found in the Canadian Arctic but also the first hypersaline subglacial lakes reported to date, each estimated to be around 5 and 8.3 square kilometers.
The lakes, which are described as “unprecedented” in the study, are of great interest to researchers for their unique characteristics: both are hypersaline and spatially isolated. This isolation from outside influences may reach back 120,000 years ago, when the lakes were covered by glacial ice.
The lakes could represent significant microbial habitats, which could be used as analogs to study the conditions for potential life on other planets. Specifically, the study states that these lakes could represent similar environments to the potential brine bodies within Europa’s ice shell or Martian polar ice caps.
“Because these subglacial systems are isolated for tens of thousands of years, they are excellent candidates to explore life processes in extreme conditions,” states Alexandre Anesio, a professor and researcher at the University of Bristol who studies the biogeochemistry of the cryosphere. He sees this opportunity as “one of the best ways to explore the limits of life on other planets.”
The newfound potential of these lakes came as a shock, Anja Rutishauser, one of the study’s researchers, told GlacierHub. “The original research goal was to better understand these basal conditions of Devon Ice Cap, as they largely affect ice dynamics and how ice flow might change under future climatic conditions. We expected to find subglacial water signatures in the faster-flowing marine-terminating outlet glaciers, but certainly not in the center of Devon Ice Cap.”Rutishauser added that the ice cap was expected to have ice frozen to the ground, not liquid water or entire subglacial lakes.
The discovery was made when the researchers analyzed radio-echo sounding measurement data. Models further analyzed the basal ice temperature. It measured 10.5 degrees Celsius, which led to the conclusion that the hypersalinity was significantly depressing the freezing point temperature. Further, the study found that this is in “agreement with surrounding geology, situated within an evaporite-rich sediment unit containing a bedded salt sequence,” the likely source for the salt. The exact origins of the subglacial lakes and the processes that formed them remain unclear, but similar bodies can offer clues to the specifics of the Canadian lakes.
According to the study, Taylor Glacier in Antarctica contains the most comparable subglacial fluid to the Canadian lakes, with similar temperature and salinity measurements. However, it is sourced from ancient marine water and not spatially isolated. Taylor Glacier’s outflows have been found to have active microbial communities, which leads researchers to believe the same is possible in the Devon Ice Cap.
Many subglacial lakes in Antarctica and Greenland share other similarities with the Canadian lakes, further bolstering the study’s evidence. “Almost all the effort on subglacial lake exploration is concentrated in Antarctica, but this study reveals that there are other excellent locations for subglacial lake exploration,” according to Anesio. However, he believes further exploration is no trivial task considering the engineering challenge to drill cleanly into a subglacial lake without the risk of contaminating it. “However, it is certainly worth a try,” he said.
This is precisely how the researchers plan to follow up on their unprecedented discovery. “Our long-term vision is to cleanly access these lakes in order to derive if life exists,” added Rutishauser.
For now, Rutishauser said the research team is partnering with the W. Garfield Weston Foundation this spring to perform a more detailed aerogeophysical survey over Devon Ice Cap to derive more information about the lakes, including their hydrological and geological contexts.
High above the Arctic Circle, far from the footprint of human civilization, a significant indication of human-induced climate change has manifested in Lake Hazen, the largest lake by volume north of the Arctic Circle. The lake and surrounding glacial environment are experiencing rapid change as the climate warms, ice cover declines, and glaciers retreat. A recent study in Nature Communications examines these physical drivers and their impacts on the lake’s ecological composition and the physiological condition of its only fish species, the Arctic Char. These changes, unprecedented in 300 years, have serious ramifications for local indigenous populations who rely on the lake’s ecosystem services.
In northern Ellesmere Island, the farthest north of the islands that compose the Canadian Arctic Archipelago, summer air temperatures increased by 1 degree Celsius during the 2001 to 2012 period in comparison to the period 1986 to 2000. Climate model simulations suggest temperatures are expected to increase 3.2 degrees Celsius by 2100. These changes have the potential to dramatically alter local ecosystems.
The study’s research team, which included experienced Arctic scientists from a diverse set of backgrounds, grew over time, according to Igor Lehnherr, who spoke with GlacierHub. From a scientific standpoint, the team knew that glacial masses were shrinking in other parts of the Arctic, along with summer lake ice cover. From this basis, according to Lehnherr, it was ”a matter of bringing everyone on board with all the different expertise required to quantify each of these various aspects.”
The study’s authors note that few previous studies have evaluated ecosystem-scale changes to climate change in inland watersheds. Lehnherr cited the need for a multidisciplinary team and baseline data to “quantify how much the system has changed and what drivers are responsible for ecological change” as challenges to study.
The researchers benefitted from over 50 years of scientific research on Lake Hazen, helping this recent study fill part of this knowledge gap by analyzing how the lake’s ecosystem has responded to climate change. The study does this through four distinct, yet interconnected focuses: watershed warming and declining lake ice cover, hydrological changes within the watershed, recent changes in the paleo-lake record, and ecological shifts in the lake itself.
Watershed Warming and Declining Lake Ice Cover
From 2000 to 2012, summer air temperatures in the Lake Hazen watershed rose by 2.6 degrees Celsius, with most of the rise occurring after 2007. These higher air temperatures, in turn, warmed the soil. Spring-time soil temperatures were 4 degrees Celsius higher from 2007 to 2012 than they were from 1994 to 2006. The lake warms particularly in late spring, when it is still covered by ice, and in early summer, when ice cover finally breaks up. Overall, the lake’s warming trend is causing ice to melt earlier in the summer and freeze later in the fall. This is in addition to an increase in ice-free area by 3 km2 per year since 2000, which was found to be related to August lake surface temperatures.
Hydrological Changes within the Watershed
Glaciers within the Lake Hazen watershed are the main hydrological driver. Because of warming temperatures, these glaciers are experiencing mass-balance losses. Positive feedback loops play a role in this loss, as high surface temperatures melt ice, subsequently decreasing reflectivity, which allows the surrounding surface to absorb more solar radiation, speeding up melting.
Mean rates of annual glacial runoff have increased significantly in recent years. This increase has raised water levels in Lake Hazen by almost a meter since 2007. Finally, the large increase in glacial runoff into Lake Hazen has lowered the time that water stays in the lake (before leaving by the lake’s one outflow stream) from a historical average of 89 years to 25 years today.
Recent Changes in the Paleo-Lake Record
The increase in glacial runoff entering Lake Hazen has driven sediment accumulation rates to levels eight times higher than a 1948 baseline period. Most runoff is deposited by glacier-fed rivers that empty into the lake, leading to the increased mixing and oxygenation of the lake’s once stable and anoxic bottom waters.
More sediment deposition has also given rise to increased levels of anthropogenic contaminants, such as mercury and pesticides, in lake sediments. In addition, organic carbon accumulation rates in the lake have increased by an astonishing 1000 percent, much higher than the 50 percent increase in most North American boreal lakes.
To assess the impact of the lake’s changes outlined above on its ecology, the authors used micro-fossil counts of algae. Before widespread warming (prior to 1890), when the lake was covered with ice almost year-round, algal fossils were rare. However, after warming (post 1890), when more areas of the lake became ice-free, nearshore algal species boomed.
After remaining relatively stable for much of the 20th century, the lake’s ecological composition changed in the late 1980s when planktonic species succeeded benthic species. This change was driven by a longer ice-free period where the deep waters of the lake were exposed to light for more months each year.
Lake Hazen’s one fish species, the Arctic Char, has also been negatively impacted by climate warming. Lehnherr notes that the team might have expected ice-free summers to increase the lake’s primary productivity, subsequently increasing biomass and leading to healthier and thriving Char populations. However, this has yet to occur; instead, amplified lake turbidity due to the raised levels of glacial river discharge has hindered the ability of the visually reliant Char to feed on midges and other Char, harming their physiological condition.
These changes have negative effects on the lake’s ecology and also on indigenous communities that inhabit the area. These communities rely on the lake as a source of food in an otherwise desolate region. While the future of High Arctic ecosystems is far from certain, Lehnherr points to the need for more multidisciplinary studies that encompass entire watersheds as a key to the better assessment of climate change impacts.
Baffin Island in Nunavut, Canada, has served as the backdrop for dozens of investigations into glaciation and ice-age patterns. Now a new paper takes a unique look at assigning ages to some of the oldest moraines from the most recent episode of glacier expansion in the Canadian Arctic.
Moraines, ridges of debris deposited alongside or in front of a glacier, can contain valuable data for understanding past climate. The positions of these debris are controlled by temperature and precipitation, which when combined with moraine dating can help construct a picture of past glacier margins. Ice-cored moraines fronting debris-covered glaciers, like the ones this paper investigated, are formed when glaciers with debris on them, like rocks and sediment, retreat and leave behind sections of debris-covered ice. Over time, that ice slowly melts— and its melt-rate is affected (often further slowed) by all the debris that cover and protect the ice from solar radiation. These ice-cored moraines, named because they are moraines with remnants of glacial ice, are notoriously difficult to study because there are many factors that influence how accurately they can be dated. Fully extrapolating the glaciers’ positions and age from the ice-cored moraines also depends on the long history of temperature and precipitation in the area, which contributes to glacier formation and melting. However, when all these factors are accounted for, the positions of these debris can show the location of past glacier margins, reflecting the size of glaciers in the past.
To date the moraines, the researchers examine the concentration of a beryllium isotope, 10Be, that accumulates only in some minerals (like quartz) in the uppermost layers of rocks. The rate of accumulation is well understood and based on cosmic ray interactions in the atmosphere and within the rock itself. Since only rocks on the earth’s surface accumulate 10Be, researchers can calculate how long that rock was exposed on the earth’s surface by comparing the concentrations of isolating a sample of 10Be in a rock from a moraine to other well-dated rocks. GlacierHub spoke with Sarah Crump, the lead author on this paper, who explained that with this information “we can estimate when a glacier was extended to the location of the moraine, and thereby make inferences about climate at the time.” Using this data, they reported that the moraines likely formed5,200 to 3,500 years ago during the Neoglaciation of the Late Holocene.
However, 10Be dating has some uncertainty.Crump and her team realized that because “the 10Be ages exhibited quite a bit of spread,” they needed to take a closer look at the glacial setting and mechanics of moraine formation. “We thus teamed up with co-author Leif Anderson to collect glaciological data at the field sites and model a simplified, representative debris-covered glacier,” she said. Additionally, they used field observations of the moraines to decipher if the debris had evolved since their initial formation. The researchers looked for evidence of morphological changes caused by uneven ice melting over time, or moraine degradation leading to surface boulders to roll and new boulder faces to emerge— all of which can affect 10Be dates. The results of the paper combine findings from these three methods: 10Be dating (or more formally cosmogenic radionuclide dating), numerical modeling based on field collected glaciological data, and field observations for moraine evolution.
Due to this collaboration and methodology, this study is unique. Michael Kaplan, a paleoclimatologist at Columbia University, commented on the novelty of this research: “I am not familiar with another paper that uses these three approaches (and the different respective experts as coauthors) in the manner that Crump et al. do.”
Though this combination of methods is novel, Crump stated that there are still some uncertainties in the precise formation age of the moraines. Often, 10Be dating results can deliver ages that are either older or younger than the actual age of the moraines. For example, rocks and boulders that ended up on a moraine might have arrived before glacial erosion, which would result in an age that was too old. The other two methods— field observations and numerical modeling— helped inform their final conclusions and significantly reduced uncertainty (though some uncertainty inherent to 10Be dating can never be completely eliminated).
Overall, Crump hopes that “readers will take note of the very important role of debris in glacier systems, both in terms of how they respond to climate variability and in terms of their geomorphic effect on the landscape.” These results show the importance of taking into account the glacial setting and help to clarify and identify some of the uncertainty around the moraine record, giving a deeper understanding of the relationship between glacier fluctuation and climate variability, allowing researchers to gather more detailed and accurate information about past climates and therefore better assess the future.
If you’re interested in learning more about the area, Gifford Miller, a co-author of the paper has an informative video about Baffin Island and its importance.