Drivers, dynamics and impacts of changing Arctic coasts

Irrgang, Anna; Bendixen, Mette; Farquharson, Louise M.; Baranskaya, Alisa; Erikson, Li H.; Gibbs, Ann E.; Ogorodov, Stanislav; Overduin, Paul; Lantuit, Hugues; Grigoriev, Mikhail N.; Jones, Benjamin M.

doi:10.1038/s43017-021-00232-1

Cited by 110 publications

(95 citation statements)

References 169 publications

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“…Hence, these materials will not experience the consumption of latent heat in the process of permafrost-heating. This may cause the observed climate change-driven permafrost degradation to be substantially faster than in previous predictions [89], even without taking thermokarst-inducing processes [83] and AA effects [86,90] into account.…”

Section: Impact Of Climate Change On Permafrost Heatingmentioning

confidence: 71%

Numerical Simulation of Coastal Sub-Permafrost Gas Hydrate Formation in the Mackenzie Delta, Canadian Arctic

Spangenberg

Schicks

et al. 2022

Energies

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The Mackenzie Delta (MD) is a permafrost-bearing region along the coasts of the Canadian Arctic which exhibits high sub-permafrost gas hydrate (GH) reserves. The GH occurring at the Mallik site in the MD is dominated by thermogenic methane (CH4), which migrated from deep conventional hydrocarbon reservoirs, very likely through the present fault systems. Therefore, it is assumed that fluid flow transports dissolved CH4 upward and out of the deeper overpressurized reservoirs via the existing polygonal fault system and then forms the GH accumulations in the Kugmallit–Mackenzie Bay Sequences. We investigate the feasibility of this mechanism with a thermo–hydraulic–chemical numerical model, representing a cross section of the Mallik site. We present the first simulations that consider permafrost formation and thawing, as well as the formation of GH accumulations sourced from the upward migrating CH4-rich formation fluid. The simulation results show that temperature distribution, as well as the thickness and base of the ice-bearing permafrost are consistent with corresponding field observations. The primary driver for the spatial GH distribution is the permeability of the host sediments. Thus, the hypothesis on GH formation by dissolved CH4 originating from deeper geological reservoirs is successfully validated. Furthermore, our results demonstrate that the permafrost has been substantially heated to 0.8–1.3 °C, triggered by the global temperature increase of about 0.44 °C and further enhanced by the Arctic Amplification effect at the Mallik site from the early 1970s to the mid-2000s.

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Section: Impact Of Climate Change On Permafrost Heatingmentioning

confidence: 71%

Numerical Simulation of Coastal Sub-Permafrost Gas Hydrate Formation in the Mackenzie Delta, Canadian Arctic

Spangenberg

Schicks

et al. 2022

Energies

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“…Subsequently, two important coastal indicator features, the waterline and tundra line, were extracted with encouraging results. We attribute some of the inconsistencies to the complexity and variability of the coastal zone (Figure 6), which is a frequent issue described in the coastal erosion literature [64].…”

Section: Discussionmentioning

confidence: 97%

Multiscale Object-Based Classification and Feature Extraction along Arctic Coasts

et al. 2022

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Permafrost coasts are experiencing accelerated erosion in response to above average warming in the Arctic resulting in local, regional, and global consequences. However, Arctic coasts are expansive in scale, constituting 30–34% of Earth’s coastline, and represent a particular challenge for wide-scale, high temporal measurement and monitoring. This study addresses the potential strengths and limitations of an object-based approach to integrate with an automated workflow by assessing the accuracy of coastal classifications and subsequent feature extraction of coastal indicator features. We tested three object-based classifications; thresholding, supervised, and a deep learning model using convolutional neural networks, focusing on a Pleaides satellite scene in the Western Canadian Arctic. Multiple spatial resolutions (0.6, 1, 2.5, 5, 10, and 30 m/pixel) and segmentation scales (100, 200, 300, 400, 500, 600, 700, and 800) were tested to understand the wider applicability across imaging platforms. We achieved classification accuracies greater than 85% for the higher image resolution scenarios using all classification methods. Coastal features, waterline and tundra, or vegetation, line, generated from image classifications were found to be within the image uncertainty 60% of the time when compared to reference features. Further, for very high resolution scenarios, segmentation scale did not affect classification accuracy; however, a smaller segmentation scale (i.e., smaller image objects) led to improved feature extraction. Similar results were generated across classification approaches with a slight improvement observed when using deep learning CNN, which we also suggest has wider applicability. Overall, our study provides a promising contribution towards broad scale monitoring of Arctic coastal erosion.

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“…Most Arctic coasts are eroding rapidly [76,77], and waves are a clear driver of these changes [78][79][80][81]. The presence and absence of sea ice controls the wave exposure at the coast, with strong regional variability [82].…”

Section: (C) Coastal Impactsmentioning

confidence: 99%

Wave propagation in the marginal ice zone: connections and feedback mechanisms within the air–ice–ocean system

Thomson

2022

Phil. Trans. R. Soc. A.

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The propagation of ocean surface waves within the marginal ice zone (MIZ) is a defining phenomenon of this dynamic zone. Over decades of study, a variety of methods have been developed to observe and model wave propagation in the MIZ, with a common focus of determining the attenuation of waves with increasing distance into the MIZ. More recently, studies have begun to explore the consequences of wave attenuation and the coupled processes in the air–ice–ocean–land system. Understanding these coupled processes and effects is essential for accurate high-latitude forecasts. As waves attenuate, their momentum and energy are transferred to the sea ice and upper ocean. This may compact or expand the MIZ, depending on the conditions, while simultaneously modulating the wind work on the system. Wave attenuation is also a key process in coastal dynamics, where land–fast ice has historically protected both natural coasts and coastal infrastructure. With observed trends of increasing wave activity and retreating seasonal ice coverage, the propagation of waves within the MIZ is increasingly important to regional and global climate trends. This article is part of the theme issue ‘Theory, modelling and observations of marginal ice zone dynamics: multidisciplinary perspectives and outlooks’.

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Drivers, dynamics and impacts of changing Arctic coasts

Cited by 110 publications

References 169 publications

Numerical Simulation of Coastal Sub-Permafrost Gas Hydrate Formation in the Mackenzie Delta, Canadian Arctic

Numerical Simulation of Coastal Sub-Permafrost Gas Hydrate Formation in the Mackenzie Delta, Canadian Arctic

Multiscale Object-Based Classification and Feature Extraction along Arctic Coasts

Wave propagation in the marginal ice zone: connections and feedback mechanisms within the air–ice–ocean system

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