Numerical model of late Pleistocene and Holocene ice-sheet and shoreline dynamics in the southern Baltic Sea, Poland

Abstract

This paper reveals deglaciation palaeodynamics (Marine Oxygen Isotope Stage 2 [MIS 2]) in Poland and the southern Baltic Sea (SBS) development during marine transgression/regression phases (MIS 1) determined by a numerical modelling method. The introduced approach uses a high-level polynomial regression followed by the integral calculus of successive functions and an application of formulae. As a result, palaeogeographic relations from primary matrix transform instantly into palaeodynamics within a nested matrix. Accordingly, within 9 ka of the late Pleistocene, glacial recession dynamics increased by two orders of magnitude, from −8.5 m/yr between Leszno (L, 24 ka BP) and Poznań (Poz, 20-19 ka BP) phases, through several dozen (−37.2 m/yr, −60.6 m/yr, −90.7 m/yr) to the maximum average equalling −427.3 m/yr (max. −861.4 m/yr) between the Pomeranian (Pom, 17-16 ka BP) and the Gardno (G, 16.8-16.6 ka BP) phases. In turn, SBS coastline transgression and regression dynamics varied by three orders of magnitude. Since the Baltic Ice Lake (BIL, 10.5-10.3 ka BP) up to the Yoldia Sea (YS, 10-9.9 ka BP) regression was intense and equalled −56.8 m/yr (max. −128.7 m/yr), followed by marine transgression towards the Ancylus Lake (AL, 8.7-8.5 ka BP) at 21.43 m/yr through 9.30-2.20 m/yr during the Littorina Sea 1 and Littorina Sea 2 stages (LS1 and LS2, since 7.7 ka BP), eventually 0.51 m/yr in the last 6.05 ka. The 2 m sea-level rise scenario projections indicate approx. 3400 km2 of land and 684,000 inhabitants face flood risk around 2150-2240 CE, with marine transgression dynamics expected to range from 23.9-38.2 m/yr.