Arctic permafrost is degrading and is thus releasing nutrients, solutes, sediment and water into soils and freshwater ecosystems. The impacts of this degradation depends on the geochemical characteristics and in large part on the spatial distribution of ground ice and solutes, which is not well-known in the High Arctic polar desert ecosystems. This research links ground ice and solute concentrations, to establish a framework for identifying locations vulnerable to permafrost degradation. It builds on landscape classifications and cryostratigraphic interpretations of permafrost history. Well-vegetated wetland sites with syngenetic permafrost aggradation show a different geochemical signature from polar desert and epigenetic sites. In wetlands, where ground ice contents were high (<97% volume), total dissolved solute concentrations were relatively low (mean 283.0 ± 327.8 ppm), reflecting a carbonate terrestrial/freshwater setting. In drier sites with epigenetic origin, such as polar deserts, ice contents are low (<47% volume), solute concentrations were high (mean 3248.5 ± 1907.0 ppm, max 12055 ppm) and dominated by Na + and Cl − ions, reflecting a post-glacial marine inundation during permafrost formation. Dissolved organic carbon and total dissolved nitrogen concentrations usually increased at the top of permafrost and could not be as clearly associated with permafrost history. The research shows that the geochemistry of polar desert permafrost is highly dependent on permafrost history, and it can be estimated using hydrogeomorphological terrain classifications. The lower ice content of polar desert sites indicates that these areas are more vulnerable to thaw relative to the ice-rich wetland sites, and the elevated solute concentrations indicate that these areas could mobilise substantial solutes to downstream environments, should they become hydrologically connected with future warming.
Abstract Field records, aerial photographs, and satellite imagery show that the perennial ice cover on Ward Hunt Lake at Canada's northern coast experienced rapid contraction and thinning after at least 50 years of relative stability. On all dates of sampling from 1953 to 2007, 3.5 to 4.3 m of perennial ice covered 65–85% of the lake surface in summer. The ice cover thinned from 2008 onward, and the lake became ice free in 2011, an event followed by 26 days of open water conditions in 2012. This rapid ice loss corresponded to a significant increase in melting degree days (MDD), from a mean (±SD) of 80.4 (±36.5) MDD (1996–2007) to 136.2 (±16.4) MDD (2008–2012). The shallow bathymetry combined with heat advection by warm inflows caused feedback effects that accelerated the ice decay. These observations show how changes across a critical threshold can result in the rapid disappearance of thick perennial ice.
Abstract Mean annual air temperatures in the High Arctic are rising rapidly, with extreme warming events becoming increasingly common. Little is known, however, about the consequences of such events on the ice‐capped lakes that occur abundantly across this region. Here, we compared 2 years of high‐frequency monitoring data in Ward Hunt Lake in the Canadian High Arctic. One of the years included a period of anomalously warm conditions that allowed us to address the question of how loss of multi‐year ice cover affects the limnological properties of polar lakes. A mooring installed at the deepest point of the lake (9.7 m) recorded temperature, oxygen, chlorophyll a (Chl a ) fluorescence, and underwater irradiance from July 2016 to July 2018, and an automated camera documented changes in ice cover. The complete loss of ice cover in summer 2016 resulted in full wind exposure and complete mixing of the water column. This mixing caused ventilation of lake water heat to the atmosphere and 4°C lower water temperatures than under ice‐covered conditions. There were also high values of Chl a fluorescence, elevated turbidity levels and large oxygen fluctuations throughout fall and winter. During the subsequent summer, the lake retained its ice cover and the water column remained stratified, with lower Chl a fluorescence and anoxic bottom waters. Extreme warming events are likely to shift polar lakes that were formerly capped by continuous thick ice to a regime of irregular ice loss and unstable limnological conditions that vary greatly from year to year.
Research on permafrost has intensified in recent years, due to enhanced warming in the Arctic and in alpine
regions, and the direct feedbacks between thawing permafrost and climate. To explore how scientists build
on existing knowledge on permafrost and identify which studies inspire more research, we analyzed scientific
articles published over two decades, before (1998-2007) and after (2008-2017) the 4th International Polar Year
(2007/2008). We compared this bibliometric data to results from an online survey in which respondents were
asked to list the most influential and inspiring publications on permafrost in their view.
While publications per year have more than doubled for multidisciplinary geosciences from 1998 to 2017,
permafrost publications have increased more than six-fold for the same period, according to bibliometric data
from Web of Science. Permafrost publications have increased the most in journals focusing on biogeosciences
(e.g. Journal of Geophysical Research - Biogeosciences) but also in the broader geoscience and science journals
(e.g. Geophysical Research Letters, Nature), reflecting a shift towards more carbon-cycle focused research in later years. From the survey, many listed books as the most influential publications and comments also revealed that conferences, photographs, movies and (non-science) books inspire permafrost researchers. Keeping track on how knowledge is collectively built within a scientific discipline and community, can help us to identify how to design impactful studies and how to coordinate research efforts in a time when high quality and impact research is badly needed.
Abstract. Thermokarst lakes are widespread and diverse across permafrost regions and they are considered significant contributors to global greenhouse gas emissions. Paleoenvironmental reconstructions documenting the inception and development of these ecologically important water bodies are generally limited to Pleistocene-age permafrost deposits (Yedoma) of Siberia, Alaska, and the western Canadian Arctic. Here we present the gradual transition from syngenetic ice-wedge polygon terrains to a thermokarst lake in the Eastern Canadian Arctic. We combine geomorphological surveys with paleolimnological reconstructions from sediment cores in an effort to characterize local landscape evolution from terrestrial to freshwater environment. Located on an ice-rich and organic-rich polygonal terrace, the studied lake is now evolving through active thermokarst, as revealed by subsiding and eroding shores, and was likely created by water pooling within a pre-existing topographic depression. Organic sedimentation in the valley started during the mid-Holocene, as documented by the oldest organic debris found at the base of one sediment core and dated at 4.8 kyr BP. Local sedimentation dynamics were initially controlled by fluctuations in wind activity, local moisture and vegetation growth/accumulation, as shown by alternating loess (silt) and peat layers. Fossil diatom assemblages were likewise influenced by local hydro-climatic conditions and reflect a broad range of substrates available in the past (both terrestrial and aquatic). Such conditions likely prevailed until ~ 2000 BP, when peat accumulation stopped as water ponded the surface of degrading ice-wedge polygons, and the basin progressively developed into a thermokarst lake. Interestingly, this happened in the middle of the Neoglacial cooling period, likely under wetter-than-average conditions. Thereafter, the lake continued to develop as evidenced by the dominance of aquatic (both benthic and planktonic) diatom taxa in organic-rich lacustrine muds. Based on these interpretations, we present a four-stage conceptual model of thermokarst lake development during the late Holocene, including some potential future trajectories. Such a model could be applied to other formerly glaciated syngenetic permafrost landscapes.
Abstract. In formerly glaciated permafrost regions, extensive areas are still underlain by a considerable amount of glacier ice buried by glacigenic sediments. It is expected that large parts of glacier ice buried in the permafrost will melt in the near future, although the intensity and timing will depend on local terrain conditions and the magnitude and rate of future climate trends in different Arctic regions. The impact of these ice bodies on landscape evolution remains uncertain since the extent and volume of undisturbed relict glacier ice are unknown. These remnants of glacier ice buried and preserved in the permafrost contribute to the high spatial variability in ground ice condition of these landscapes, leading to the formation of lakes with diverse origins and morphometric and limnological properties. This study focuses on thermokarst lake initiation and development in response to varying ground ice conditions in a glacial valley on Bylot Island (Nunavut). We studied a lake-rich area using lake sediment cores, detailed bathymetric data, remotely sensed data and observations of buried glacier ice exposures. Our results suggest that initiation of thermokarst lakes in the valley was triggered from the melting of either buried glacier ice or intrasedimental ice and ice wedges. Over time, all lakes enlarged through thermal and mechanical shoreline erosion, as well as vertically through thaw consolidation and subsidence. Some of them coalesced with neighbouring water bodies to develop larger lakes. These glacial thermokarst lakes formed in buried glacier ice now evolve as “classic” thermokarst lakes that expand in area and volume as a result of the melting of intrasedimental ground ice in the surrounding material and the underlying glaciofluvial and till material. It is expected that the deepening of thaw bulbs (taliks) and the enlargement of Arctic lakes in response to global warming will reach undisturbed buried glacier ice where it is still present, which in turn will substantially alter lake bathymetry, geochemistry and greenhouse gas emissions from Arctic lowlands.
The Permafrost Young Researchers’ Workshop 2014, held during the latest European Conference on
Permafrost in Evora, Portugal (June 2014) gathered 100 early career researchers from 20 countries to
discuss and elaborate on the future of permafrost research. The event was a joint initiative of the two
major early career researcher associations Permafrost Young Researchers Network (PYRN) and the
Association of Polar Early career Scientists (APECS), as well as the regional research projects PAGE21
(EU) and ADAPT (Canada).
Early career permafrost researchers worldwide were invited to submit important questions for
permafrost research in the coming decade through an online survey. In total, 71 questions were
submitted by 31 people from 15 countries, including males (54 %) and females (46 %), ranging from
undergraduate students (19 %) to PhD students (35 %) and post docs (42 %).
During the workshop, small groups of participants reviewed sets of submitted questions,
grouped by topic, in an elaborate discussion exercise. The questions were evaluated using a series of
predefined criteria to provide realistic and sound research questions. In each discussion group, questions
were criticized, merged and re-written until each group produced a comprehensive question to submit to
the rest of the participants. The participants then voted to elect questions that best represented the most
important research avenues for permafrost research for the next decade. The top five questions that
emerged from this process are:
- How does permafrost degradation affect landscape dynamics at different spatio-temporal scales and
which are the most important processes controlling these dynamics?
- How can ground temperature models be improved to better represent factors affecting degradation,
preservation, and aggradation of permafrost at high spatial resolutions?
- In what ways can traditional knowledge be quantified and used in permafrost research?
- What is the spatial distribution and the thaw susceptibility of massive ground ice, syngenetic ground ice,
and epigenetic ground ice?
- What is the influence of different types of infrastructure on the permafrost thermal regime and stability in
different environmental settings?
These questions relate to many disciplinary areas of research, including landscape dynamics, modeling,
traditional knowledge, geocryology, and engineering. This effort engaged early career permafrost
researchers in a constructive discussion, and reflection on the future directions of their field of research.
These participants represent a new generation of permafrost researchers and offer a fresh insight into
permafrost science, an important area within Arctic research. As such, the results of this effort provide an
important perspective to consider in the future research agendas that are about to be redefined at
international level.
