In:
Earth System Dynamics, Copernicus GmbH, Vol. 13, No. 1 ( 2022-01-25), p. 159-199
Abstract:
Abstract. The Baltic Sea, located in northern Europe, is a semi-enclosed, shallow and tideless sea with seasonal sea-ice cover in its northern sub-basins. Its long water residence time contributes to oxygen depletion in the bottom water of its southern sub-basins. In this study, recently performed scenario simulations for the Baltic Sea including marine biogeochemistry were analysed and compared with earlier published projections. Specifically, dynamical downscaling using a regionally coupled atmosphere–ocean climate model was used to regionalise four global Earth
system models. However, as the regional climate model does not include
components representing terrestrial and marine biogeochemistry, an additional catchment and a coupled physical–biogeochemical model for the
Baltic Sea were included. The scenario simulations take the impact of various global sea level rise scenarios into account. According to the projections, compared to the present climate, higher water temperatures, a shallower mixed layer with a sharper thermocline during summer, less sea-ice cover and greater mixing in the northern Baltic Sea during winter can be expected. Both the frequency and the duration of marine heat waves will increase significantly, in particular in the coastal zone of the southern Baltic Sea (except in regions with frequent upwellings). Nonetheless, due to the uncertainties in the projections regarding regional winds, the water cycle and the global sea level rise, robust and statistically significant salinity changes could not be identified. The impact of a changing climate on biogeochemical cycling is predicted to be considerable but still smaller than that of plausible nutrient input changes. Implementing the proposed Baltic Sea Action Plan, a nutrient input abatement plan for the entire catchment area, would result in a significantly improved ecological status of the Baltic Sea, including
reductions in the size of the hypoxic area also in a future climate, which
in turn would increase the resilience of the Baltic Sea against anticipated
climate change. While our findings regarding changes in heat-cycle variables mainly confirm earlier scenario simulations, they differ substantially from earlier projections of salinity and biogeochemical cycles, due to differences in experimental setups and in input scenarios for bioavailable nutrients.
Type of Medium:
Online Resource
ISSN:
2190-4987
DOI:
10.5194/esd-13-159-2022
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2022
detail.hit.zdb_id:
2578793-7
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