Initial Validation Results for the Arctic Coastal Erosion (ACE) Model.

Abstract. Permafrost landscapes are changing around the Arctic in response to climate warming, with coastal erosion being one of the most prominent and hazardous features. Using drone platforms, satellite images, and historic aerial photographs, we observed the rapid retreat of a permafrost coastline on Qikiqtaruk – Herschel Island, Yukon Territory, in the Canadian Beaufort Sea. This coastline is adjacent to a gravel spit accommodating several culturally significant sites and is the logistical base for the Qikiqtaruk – Herschel Island Territorial Park operations. In this study we sought to (i) assess short-term coastal erosion dynamics over fine temporal resolution, (ii) evaluate short-term shoreline change in the context of long-term observations, and (iii) demonstrate the potential of low-cost lightweight unmanned aerial vehicles (“drones”) to inform coastline studies and management decisions. We resurveyed a 500 m permafrost coastal reach at high temporal frequency (seven surveys over 40 d in 2017). Intra-seasonal shoreline changes were related to meteorological and oceanographic variables to understand controls on intra-seasonal erosion patterns. To put our short-term observations into historical context, we combined our analysis of shoreline positions in 2016 and 2017 with historical observations from 1952, 1970, 2000, and 2011. In just the summer of 2017, we observed coastal retreat of 14.5 m, more than 6 times faster than the long-term average rate of 2.2±0.1 m a−1 (1952–2017). Coastline retreat rates exceeded 1.0±0.1 m d−1 over a single 4 d period. Over 40 d, we estimated removal of ca. 0.96 m3 m−1 d−1. These findings highlight the episodic nature of shoreline change and the important role of storm events, which are poorly understood along permafrost coastlines. We found drone surveys combined with image-based modelling yield fine spatial resolution and accurately geolocated observations that are highly suitable to observe intra-seasonal erosion dynamics in rapidly changing Arctic landscapes.

Download Full-text

Rising Seas and Retreating Coasts: Implications for the Arctic

The International Journal of Marine and Coastal Law ◽

10.1163/15718085-bja10016 ◽

2020 ◽

Vol 35 (3) ◽

pp. 468-497

Author(s):

Clive Schofield ◽

Suzanne Lalonde

Keyword(s):

Climate Change ◽

Sea Level ◽

Coastal Erosion ◽

Legal Issues ◽

The Arctic ◽

Future Challenge ◽

Legal Regime ◽

Legal Responses ◽

Key Aspects ◽

Impacts Of Climate Change

Abstract This article addresses both the physical impacts and international legal issues arising from two interlinked stressors on Arctic coastlines: sea level rise and coastal erosion. Key aspects of the legal regime governing the baselines from which coastal States calculate the outer limits of their maritime zones are reviewed and a synopsis of the practice among the Arctic littoral States is provided. The article then turns to a discussion of the practical and international legal responses available to deal with the present and future challenge of rising seas and retreating coasts. The concluding section offers with some reflections on the way forward for a region experiencing some of the most devastating impacts of climate change.

Download Full-text

Macromolecular composition of terrestrial and marine organic matter in sediments across the East Siberian Arctic Shelf

The Cryosphere ◽

10.5194/tc-10-2485-2016 ◽

2016 ◽

Vol 10 (5) ◽

pp. 2485-2500 ◽

Cited By ~ 6

Author(s):

Robert B. Sparkes ◽

Ayça Doğrul Selver ◽

Örjan Gustafsson ◽

Igor P. Semiletov ◽

Negar Haghipour ◽

...

Keyword(s):

Organic Matter ◽

Coastal Erosion ◽

Principal Component ◽

Arctic Shelf ◽

The Arctic ◽

Gas Chromatography Mass Spectrometry ◽

Terrestrial Organic Matter ◽

Pyrolysis Gas ◽

Siberian Arctic ◽

Extractable Organic Matter

Abstract. Mobilisation of terrestrial organic carbon (terrOC) from permafrost environments in eastern Siberia has the potential to deliver significant amounts of carbon to the Arctic Ocean, via both fluvial and coastal erosion. Eroded terrOC can be degraded during offshore transport or deposited across the wide East Siberian Arctic Shelf (ESAS). Most studies of terrOC on the ESAS have concentrated on solvent-extractable organic matter, but this represents only a small proportion of the total terrOC load. In this study we have used pyrolysis–gas chromatography–mass spectrometry (py-GCMS) to study all major groups of macromolecular components of the terrOC; this is the first time that this technique has been applied to the ESAS. This has shown that there is a strong offshore trend from terrestrial phenols, aromatics and cyclopentenones to marine pyridines. There is good agreement between proportion phenols measured using py-GCMS and independent quantification of lignin phenol concentrations (r2 = 0.67, p < 0.01, n = 24). Furfurals, thought to represent carbohydrates, show no offshore trend and are likely found in both marine and terrestrial organic matter. We have also collected new radiocarbon data for bulk OC (14COC) which, when coupled with previous measurements, allows us to produce the most comprehensive 14COC map of the ESAS to date. Combining the 14COC and py-GCMS data suggests that the aromatics group of compounds is likely sourced from old, aged terrOC, in contrast to the phenols group, which is likely sourced from modern woody material. We propose that an index of the relative proportions of phenols and pyridines can be used as a novel terrestrial vs. marine proxy measurement for macromolecular organic matter. Principal component analysis found that various terrestrial vs. marine proxies show different patterns across the ESAS, and it shows that multiple river–ocean transects of surface sediments transition from river-dominated to coastal-erosion-dominated to marine-dominated signatures.

Download Full-text

Short and long-term thermo-erosion of ice-rich permafrost coasts in the Laptev Sea region

Biogeosciences Discussions ◽

10.5194/bgd-10-2705-2013 ◽

2013 ◽

Vol 10 (2) ◽

pp. 2705-2765 ◽

Cited By ~ 1

Author(s):

F. Günther ◽

P. P. Overduin ◽

A. V. Sandakov ◽

G. Grosse ◽

M. N. Grigoriev

Keyword(s):

Coastal Erosion ◽

The Arctic ◽

Laptev Sea ◽

Erosion Rates ◽

The Past ◽

Mass Fluxes ◽

Study Sites ◽

The Laptev Sea ◽

Ice Complex

Abstract. Permafrost coasts in the Arctic are susceptible to a variety of changing environmental factors all of which currently point to increasing coastal erosion rates and mass fluxes of sediment and carbon to the shallow arctic shelf seas. Rapid erosion along high yedoma coasts composed of Ice Complex permafrost deposits creates impressive coastal ice cliffs and inspired research for designing and implementing change detection studies for a long time, but continuous quantitative monitoring and a qualitative inventory of coastal thermo-erosion for large coastline segments is still lacking. Our goal is to use observations of thermo-erosion along the mainland coast of the Laptev Sea in eastern Siberia to understand how erosion rates depend on coastal geomorphology and the relative contributions of waterline and atmospheric drivers to coastal thermo-erosion over the past 4 decades and in the past few years. We compared multitemporal sets of orthorectified satellite imagery from 1965 to 2011 for three segments of coastline with a length of 73 to 95 km each and analyzed thermo-denudation (TD) along cliff top and thermo-abrasion (TA) along cliff bottom for two nested time periods: long-term rates (the past 39–43 yr) and short term rates (the past 1–3 yr). The Normalized Difference Thermo-erosion Index (NDTI) was used as a proxy that qualitatively describes the relative proportions of TD and TA. Mean annual erosion rates at all three sites were higher in recent years (−5.3 ± 1.31 m a−1) than over the long term mean (−2.2 ± 0.13 m a−1). The Mamontov Klyk coast exhibit primarily spatial variations of thermo-erosion, while intrasite-specific variations were strongest at the Buor Khaya coast, where slowest long-term rates around −0.5 ± 0.08 m a−1 were observed. The Oyogos Yar coast showed continuously rapid erosion up to −6.5 ± 0.19 m a−1. In general, variable characteristics of coastal thermo-erosion were observed not only between study sites and over time, but also within single coastal transects along the cliff profile. Varying intensities of cliff bottom and top retreat are leading to diverse qualities of coastal erosion that have different impacts on coastal mass fluxes. The different extents of Ice Complex permafrost degradation within our study sites turned out to influence not only the degree of coupling between TD and TA, and the magnitude of effectively eroded volumes, but also the quantity of organic carbon released to the shallow Laptev Sea from coastal erosion, which ranged on a long-term from 88 ± 21.0 to 800 ± 61.1 t per km coastline per year and will correspond to considerably higher amounts, if recently observed more rapid coastal erosion rates prove to be persistent.

Download Full-text

Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska

Frontiers in Earth Science ◽

10.3389/feart.2020.598933 ◽

2021 ◽

Vol 8 ◽

Author(s):

Emily M. Bristol ◽

Craig T. Connolly ◽

Thomas D. Lorenson ◽

Bruce M. Richmond ◽

Anastasia G. Ilgen ◽

...

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Late Pleistocene ◽

21St Century ◽

Marine Sediments ◽

Coastal Erosion ◽

Beaufort Sea ◽

The Arctic ◽

The Holocene ◽

Kuparuk River

Accelerating erosion of the Alaska Beaufort Sea coast is increasing inputs of organic matter from land to the Arctic Ocean, and improved estimates of organic matter stocks in eroding coastal permafrost are needed to assess their mobilization rates under contemporary conditions. We collected three permafrost cores (4.5–7.5 m long) along a geomorphic gradient near Drew Point, Alaska, where recent erosion rates average 17.2 m year−1. Down-core patterns indicate that organic-rich soils and lacustrine sediments (12–45% total organic carbon; TOC) in the active layer and upper permafrost accumulated during the Holocene. Deeper permafrost (below 3 m elevation) mainly consists of Late Pleistocene marine sediments with lower organic matter content (∼1% TOC), lower C:N ratios, and higher δ13C values. Radiocarbon-based estimates of organic carbon accumulation rates were 11.3 ± 3.6 g TOC m−2 year−1 during the Holocene and 0.5 ± 0.1 g TOC m−2 year−1 during the Late Pleistocene (12–38 kyr BP). Within relict marine sediments, porewater salinities increased with depth. Elevated salinity near sea level (∼20–37 in thawed samples) inhibited freezing despite year-round temperatures below 0°C. We used organic matter stock estimates from the cores in combination with remote sensing time-series data to estimate carbon fluxes for a 9 km stretch of coastline near Drew Point. Erosional fluxes of TOC averaged 1,369 kg C m−1 year−1 during the 21st century (2002–2018), nearly doubling the average flux of the previous half-century (1955–2002). Our estimate of the 21st century erosional TOC flux year−1 from this 9 km coastline (12,318 metric tons C year−1) is similar to the annual TOC flux from the Kuparuk River, which drains a 8,107 km2 area east of Drew Point and ranks as the third largest river on the North Slope of Alaska. Total nitrogen fluxes via coastal erosion at Drew Point were also quantified, and were similar to those from the Kuparuk River. This study emphasizes that coastal erosion represents a significant pathway for carbon and nitrogen trapped in permafrost to enter modern biogeochemical cycles, where it may fuel food webs and greenhouse gas emissions in the marine environment.

Download Full-text

Permafrost Carbon and CO2 Pathways Differ at Contrasting Coastal Erosion Sites in the Canadian Arctic

Frontiers in Earth Science ◽

10.3389/feart.2021.630493 ◽

2021 ◽

Vol 9 ◽

Author(s):

George Tanski ◽

Lisa Bröder ◽

Dirk Wagner ◽

Christian Knoblauch ◽

Hugues Lantuit ◽

...

Keyword(s):

Organic Matter ◽

Coastal Erosion ◽

Canadian Arctic ◽

Warm Season ◽

Open Water ◽

The Arctic ◽

Comprehensive Understanding ◽

Erosion Process ◽

Fresh Organic Matter ◽

Transit Times

Warming air and sea temperatures, longer open-water seasons and sea-level rise collectively promote the erosion of permafrost coasts in the Arctic, which profoundly impacts organic matter pathways. Although estimates on organic carbon (OC) fluxes from erosion exist for some parts of the Arctic, little is known about how much OC is transformed into greenhouse gases (GHGs). In this study we investigated two different coastal erosion scenarios on Qikiqtaruk – Herschel Island (Canada) and estimate the potential for GHG formation. We distinguished between a delayed release represented by mud debris draining a coastal thermoerosional feature and a direct release represented by cliff debris at a low collapsing bluff. Carbon dioxide (CO2) production was measured during incubations at 4°C under aerobic conditions for two months and were modeled for four months and a full year. Our incubation results show that mud debris and cliff debris lost a considerable amount of OC as CO2 (2.5 ± 0.2 and 1.6 ± 0.3% of OC, respectively). Although relative OC losses were highest in mineral mud debris, higher initial OC content and fresh organic matter in cliff debris resulted in a ∼three times higher cumulative CO2 release (4.0 ± 0.9 compared to 1.4 ± 0.1 mg CO2 gdw–1), which was further increased by the addition of seawater. After four months, modeled OC losses were 4.9 ± 0.1 and 3.2 ± 0.3% in set-ups without seawater and 14.3 ± 0.1 and 7.3 ± 0.8% in set-ups with seawater. The results indicate that a delayed release may support substantial cycling of OC at relatively low CO2 production rates during long transit times onshore during the Arctic warm season. By contrast, direct erosion may result in a single CO2 pulse and less substantial OC cycling onshore as transfer times are short. Once eroded sediments are deposited in the nearshore, highest OC losses can be expected. We conclude that the release of CO2 from eroding permafrost coasts varies considerably between erosion types and residence time onshore. We emphasize the importance of a more comprehensive understanding of OC degradation during the coastal erosion process to improve thawed carbon trajectories and models.

Download Full-text

The effect of changing sea ice on the physical vulnerability of Arctic coasts

The Cryosphere ◽

10.5194/tc-8-1777-2014 ◽

2014 ◽

Vol 8 (5) ◽

pp. 1777-1799 ◽

Cited By ~ 52

Author(s):

K. R. Barnhart ◽

I. Overeem ◽

R. S. Anderson

Keyword(s):

Sea Ice ◽

Water Level ◽

Coastal Erosion ◽

Open Water ◽

Water Levels ◽

The Arctic ◽

Ocean Water ◽

Physical Vulnerability ◽

Ice Edge ◽

Sea Ice Edge

Abstract. Sea ice limits the interaction of the land and ocean water in the Arctic winter and influences this interaction in the summer by governing the fetch. In many parts of the Arctic, the open-water season is increasing in duration and summertime sea-ice extents are decreasing. Sea ice provides a first-order control on the physical vulnerability of Arctic coasts to erosion, inundation, and damage to settlements and infrastructures by ocean water. We ask how the changing sea-ice cover has influenced coastal erosion over the satellite record. First, we present a pan-Arctic analysis of satellite-based sea-ice concentration specifically along the Arctic coasts. The median length of the 2012 open-water season, in comparison to 1979, expanded by between 1.5 and 3-fold by Arctic Sea sector, which allows for open water during the stormy Arctic fall. Second, we present a case study of Drew Point, Alaska, a site on the Beaufort Sea, characterized by ice-rich permafrost and rapid coastal-erosion rates, where both the duration of the open-water season and distance to the sea-ice edge, particularly towards the northwest, have increased. At Drew Point, winds from the northwest result in increased water levels at the coast and control the process of submarine notch incision, the rate-limiting step of coastal retreat. When open-water conditions exist, the distance to the sea ice edge exerts control on the water level and wave field through its control on fetch. We find that the extreme values of water-level setup have increased consistently with increasing fetch.

Download Full-text

Sensitivity of organic carbon fluxes from Arctic coastal erosion to climate change

10.5194/egusphere-egu21-13268 ◽

2021 ◽

Author(s):

David Marcolino Nielsen ◽

Patrick Pieper ◽

Victor Brovkin ◽

Paul Overduin ◽

Tatiana Ilyina ◽

...

Keyword(s):

Climate Change ◽

Organic Carbon ◽

Sea Ice ◽

Coastal Erosion ◽

Earth System Model ◽

System Model ◽

The Arctic ◽

Earth System ◽

Carbon Release ◽

Arctic Coast

When unprotected by sea-ice and exposed to the warm air and ocean waves, the Arctic coast erodes and releases organic carbon from permafrost to the surrounding ocean and atmosphere. This release is estimated to deliver similar amounts of organic carbon to the Arctic Ocean as all Arctic rivers combined, at the present-day climate. Depending on the degradation pathway of the eroded material, the erosion of the Arctic coast could represent a positive feedback loop in the climate system, to an extent still unknown. In addition, the organic carbon flux from Arctic coastal erosion is expected to increase in the future, mainly due to surface warming and sea-ice loss. In this work, we aim at addressing the following questions: How is Arctic coastal erosion projected to change in the future? How sensitive is Arctic coastal erosion to climate change?To address these questions, we use a 10-member ensemble of climate change simulations performed with the Max Planck Institute Earth System Model (MPI-ESM) for the Coupled Model Intercomparison Project phase 6 (CMIP6) to make projections of coastal erosion at a pan-Arctic scale. We use a semi-empirical approach to model Arctic coastal erosion, assuming a linear contribution of its thermal and mechanical drivers. The pan-Arctic carbon release due to coastal erosion is projected to increase from 6.9 &#177; 5.4 TgC/year (mean estimate &#177; two standard deviations from the distribution of uncertainties) during the historical period (mean over 1850 -1950) to between 13.1 &#177; 6.7 TgC/year and 17.2 &#177; 8.2 TgC/year in the period 2081-2100 following an intermediate (SSP2.4-5) and a high-end (SSP5.8-5) climate change scenario, respectively. The sensitivity of the organic carbon release from Arctic coastal erosion to climate warming is estimated to range from 1.52 TgC/year/K to 2.79 TgC/year/K depending on the scenario. Our results present the first projections of Arctic coastal erosion, combining observations and Earth system model (ESM) simulations. This allows us to make first-order estimates of sensitivity and feedback magnitudes between Arctic coastal erosion and climate change, which can lay out pathways for future coupled ESM simulations.&#160;

Download Full-text

Representing Arctic coastal erosion in the Max Planck Institute Earth System Model (MPI-ESM)

10.5194/egusphere-egu2020-10477 ◽

2020 ◽

Author(s):

David Marcolino Nielsen ◽

Johanna Baehr ◽

Victor Brovkin ◽

Mikhail Dobrynin

Keyword(s):

Carbon Cycle ◽

Sea Ice ◽

Coastal Erosion ◽

Global Carbon Cycle ◽

System Model ◽

The Arctic ◽

Earth System ◽

Max Planck ◽

Erosion Rates ◽

Global Carbon

The Arctic has warmed twice as fast as the globe and sea-ice extent has decreased, causing permafrost to thaw and the duration of the open-water period to extend. This combined effect increases the vulnerability of the Arctic coast to erosion, which in turn releases substantial amounts of carbon to both the ocean and the atmosphere, potentially contributing to further warming due to a positive climate-carbon cycle feedback. Therefore, Arctic coastal erosion is an important process of the global carbon cycle.Comprehensive modelling studies exploring Arctic coastal erosion within the Earth system are still in their infancy. Here, we describe the development of a semi-empirical Arctic coastal erosion model and its coupling with the Max Planck Institute Earth System Model (MPI-ESM). We also present preliminary results for historical and future climate projections of coastal erosion rates in the Arctic. The coupling consists on the exchange of a combination of driving forcings from the atmosphere and the ocean, such as surface air temperature, winds and sea-ice concentration, which result in annual coastal erosion rates. In a further setp, organic matter from the eroded permafrost is provided to the ocean biogeochemistry model and, consequently, to the global carbon cycle including atmospheric CO2.

Download Full-text