Past and Future Sea Level Changes and Land Uplift in the Baltic Sea Seen by Geodetic Observations

Abstract

We have studied the land uplift and relative sea level changes in the Baltic Sea in northern Europe. To observe the past changes and land uplift, we have used continuous GNSS time series, campaign-wise absolute gravity measurements and continuous tide gauge time series. To predict the future, we have used probabilistic future scenarios tuned for the Baltic Sea. The area we are interested in is Kvarken archipelago in Finland and High Coast in Sweden. These areas form a UNESCO World Heritage Site, where the land uplift process and how it demonstrates itself are the main values. We provide here the latest numbers of land uplift for the area, the current rates from geodetic observations, and probabilistic scenarios for future relative sea level rise. The maximum land uplift rates in Fennoscandia are in the Bothnian Bay of the Baltic Sea, where the maximum values are currently on the order of 10 mm/year with respect to the geoid. During the last 100 years, the land has risen from the sea by approximately 80 cm in this area. Estimates of future relative sea level change have considerable uncertainty, with values for the year 2100 ranging from 75 cm of sea level fall (land emergence) to 30 cm of sea-level rise.

Landscape constraints on mire lateral expansion

“…In northern Sweden, the rate of isostatic relaxation, or rebound, slowed down over the course of this deglaciation. The current isostatic relaxation maximum of the Scandinavian Ice Sheet is located in the Swedish province of V€ asterbotten (c. 62e64 N), where land is rising at a rate of c. 9 mm yr À1 (Nordman et al, 2020). As a result, coastal areas of the Bothnian Bay region include chronosequences that span thousands of years within only tens of kilometres from the present coastline.…”

Topography and Time Shape Mire Morphometry and Large‐Scale Mire Distribution Patterns in the Northern Boreal Landscape

“…As a result, SMC mires are primarily found on flatter ridges above the rivers and very rarely span inter‐fluvial gaps, unlike in the HBL. The Swedish part of the BBL is itself exceptional in that the rebound is occurring at the highest rate known globally (Nordman et al., 2020). Rebound is also occurring in a landscape that is comparatively more rugged than the HBL, with upslope catchment areas supplying mires with water and solutes.…”

“…Since deglaciation of the Scandinavian Ice Sheet ∼10,000 years before present (BP; Stroeven et al., 2016), land areas in this region are continuously rising from the sea due to post‐glacial isostatic rebound. The current isostatic rebound maximum of the Scandinavian Ice Sheet (9 mm yr −1 ) is located close to the SMC (Påsse & Daniels, 2015), where land is exposed from the sea at one of the highest rates globally (Nordman et al., 2020). Because of the high rebound rate as well as favorable climatic, geomorphological and hydrological conditions, the SMC has formed within a constrained distance from the present coastline (∼30 km), corresponding to a land surface age of ∼9,000 years BP (Figure 1).…”

A conceptual framework for the future of sea-level rise and land uplift changes in the Vaasa region of Finland

“…Can we fully understand the cause and effect of land uplift and sea-level rise? The authors´motivation to investigate land uplift and sea-level rise is derived from the forecast that in the local Vaasa region land uplift is expected to be the dominant movement (Nordman et al 2020). In contrast, in most other areas of the world it is sea-level rise that is forecast to dominate.…”