Relative sea-level changes along the Northern Sea Route: from patterns and rates to drivers and mechanisms

The rapidly changing climate, rising temperatures and declining Arctic sea ice have the potential to open up the Northern Sea Route (NSR). Sailing routes between Europe and East Asian ports such as Singapore through the Arctic Ocean along the NSR are about 6000 nautical miles shorter (43% shorter) than the routes around the Cape of Good Hope and are about 2700 nautical miles shorter (25% shorter) than the Europe to East Asia routes via Suez Canal. To design appropriate and operate coastal infrastructure and minimize potential risk information on future relative sea-level (RSL) and bathymetry changes in the Arctic are required. RSL projection relies on an accurate understanding of the mechanisms driving its complex spatio-temporal evolution, which must be founded on an understanding of their history. Future RSL changes along the NSR in the Eurasian Arctic are controlled by the increase in ocean mass and volume and vertical land motion from glacial-isostatic adjustment (GIA). GIA is the response of the solid Earth and gravity field to ice mass redistribution during a glacial cycle. Models of the GIA process link the cryosphere, hydrosphere and geosphere. However, the robustness of GIA models relies on the accuracy of their input parameters: ice-sheet histories and mantle rheological properties. Geological RSL data provide critical constraints on these input parameters.

There is an urgent need for high-quality geological RSL data from the Russian Arctic because global GIA models such as ICE-6G_C (VM5a) and ICE-7G_NA (VM7) have not been tuned to post Last Glacial Maximum (LGM) datasets (26,000 years ago to present) from this region. Furthermore, the thickness and extent of the Eurasian ice complex, which has a first-order control on patterns of uplift vs. subsidence in this region is poorly understood. Therefore, the ability of the current generation of GIA models to fit geological RSL data – and thus predict future RSL and bathymetric changes for the NSR – remains untested.

In this project, we will update and expand observations of RSL change along the NSR to achieve the following research objectives:

• Determining the rates, mechanisms and geographic variability of RSL along the NSR from instrumental and proxy data;
• Refine input parameters of GIA models to develop a comprehensive model for regional vertical land motion for NSR from GIA that can be incorporated into sea-level projections;
• To produce projections of RSL and bathymetry change in the 21st century along the NSR.

The proposal has three approaches. First, we will expand our post-LGM RSL database of the Russian Arctic using published data from Svalbard and Scandinavia, and unprocessed and new field data from Severnaya Zemlya and the Kara Sea. We will follow standardized international geological protocols to produce Eurasian Arctic RSL database with a full consideration of altitude and chronological uncertainties. We will use statistical models to analyse the geographical and temporal variability of RSL in the Eurasian Arctic.

Second, we will derive the viscosity structure beneath the Eurasian Arctic and deglaciation history of the Barents-Kara sector of Eurasian ice sheet using constraints provided by the RSL database. We will test the GIA models and reveal the spatial variation of sensitivity to different parameters of the lithosphere and mantle.

Third, we will project future RSL and bathymetry changes along the NSR for the 21st century. We will compare and integrate RSL and GIA patterns to understand the mechanisms of past RSL changes in the Russian Arctic that are necessary to accurately project future RSL and bathymetry changes with an associated uncertainty. Charts of the projected topography and bathymetry will be an innovative product allowing for planning of future human activity in the Arctic.

The project team has abundant experience in geological RSL database compilation and their application to constrain GIA models in North America, Europe, and the Russian Arctic. We have been conducting research on Quaternary geology and past RSL changes and ice sheet extent in this region. The regions of previous fieldwork include Barents, White, Kara, Laptev and Bering Seas coastlines and territories. We will apply our research skillsets to develop a new approach in reconstructing RSL for the Russian Arctic using cores of sediments from laidas (salt marshes). The project team has created modular, flexible and open-source framework for projection of sea level. We will use the validated GIA model and Eurasian Artic as a critical input to the flexible framework to project the sea level change along NSR. The Eurasian Artic data and models will illustrate the ways in which current methodologies and historical data sources can constrain future projections, and how accurate projections can motivate the development of new sea-level research questions across relevant timescales.

This proposal accurately captures the national interest. Since Singapore was granted observer status at the Arctic Council in 2013, it has played an active role, attending Arctic meetings, hosting workshops and sharing its experiences in tackling issues such as climate and sea-level change and a safe maritime environment.