Arctic shoreline wave erosion under a declining ice cover

Collaborating Scientists: Dr. Moritz Langer (AWI), Prof. Dr. Hugues Lantuit (AWI), Prof. Dr. Christoph Schneider (HU) and Prof. Dr. Ulf Leser (HU)

Project Outline

The erosion of carbon-rich Arctic shorelines, exacerbated by permafrost thaw and a declining sea ice cover, strongly modifies the Arctic carbon cycle and has been shown to be an important contributor to global atmospheric carbon dioxide levels during times of rapid sea level rise (Winterfeld et al., 2018).  Shoreline erosion also impacts life in the aquatic nearshore zone by supplying nutrient-laden sediment to nutrient-limited nearshore waters.  Although carbon released from Arctic shoreline erosion has the potential to impact greenhouse gas emissions, this process is unfortunately neglected in all global climate models.  Further, no stand-alone model yet exists that can hindcast or project erosion rates on a pan-Arctic scale.  The primary objective of this project is to develop a pan-Arctic, physics-based numerical model in a way that it can be coupled to global earth system models.  Such a model has broad implications for not only the geoscience community, but also for those stakeholders involved in Arctic industry (oil pipelines, communities, etc.) who are negatively impacted by retreating shorelines.  Erosion along ocean coastlines is considered, but also the significant erosion and permafrost degradation occurring along the vast number of Arctic lakes.  The Arctic coast has been identified as 101,447 km (Lantuit et. al, 2012), and the summed shoreline perimeters of Arctic lakes in the zone of continuous permafrost is roughly 80-fold that, at an estimated 8,354,530 km (Pekel et al, 2016) with the summed lake area in the zone of continuous permafrost is roughly twice the size of Germany. 

I have chosen the model developed by Kobayashi et al (1999) as a basis for this pan-Arctic numerical model.  It calculates erosion using a cliff/beach/ocean sediment volume balance, with storm surge and wave action causing convective heat transfer and thawing of ice-bonded sediment.  I am forcing it with reanalysis data and any local observations of sediment and beach properties which have been upscaled as provided in an Arctic Coastal Dynamics database (Lanuit et al, 2011).  The retreat rates are validated against existing satellite and drone observations that have already been published in multiple studies.  A by-product of my project will be the analysis of changes in the wind-wave climate along Arctic shorelines under a retreating ice cover, because this is an important forcing of the model.  Understanding changes in the wave energy applied to shorelines will help elucidate the variation of Arctic shoreline erosion rates.

Publications

Rolph, R. J., Feltham, D. L., & Schröder, D. Changes of the Arctic marginal ice zone. The Cryosphere Discussions (2019), under review for The Cryosphere, doi: 10.5194/tc-2019-224

Rolph, R. J., Mahoney, A. R., Walsh, J., & Loring, P. A. (2018). Impacts of a lengthening open water season on Alaskan coastal communities: deriving locally relevant indices from large-scale datasets and community observations. The Cryosphere, 12(5), doi: 10.5194/tc-12-1779-2018

Park, J. Y., Kug, J. S., Bader, J., Rolph, R., & Kwon, M. (2015). Amplified Arctic warming by phytoplankton under greenhouse warming. Proceedings of the National Academy of Sciences, 112(19), 5921-5926. doi: 10.1073/pnas.1416884112

Martz, T., Takeshita, Y., Rolph, R., & Bresnahan, P. (2012). Tracer monitored titrations: measurement of dissolved oxygen. Analytical chemistry, 84(1), 290-296. doi: 10.1021/ac202537f

Rolph, R. J. (2018). Mechanisms and implications of changes in the timing of ocean freeze-up. PhD Dissertation. University of Alaska Fairbanks.