Future changes in the Baltic Sea acid-base (pH) and oxygen balances

Anders Omstedt, Moa Edman, Björn Claremar, Peter Frodin, Erik Gustafsson, Christoph Humborg, Hanna Hägg, Magnus Mörth, Anna Rutgersson, Guy Schurgers, Benjamin Smith, Teresia Wällstedt, Alla Yurova

Research output: Contribution to journalArticlepeer-review

Abstract

Possible future changes in Baltic Sea acid-base (pH) and oxygen balances were studied using a catchment-sea coupled model system and numerical experiments based on meteorological and hydrological forcing datasets and scenarios. By using objective statistical methods, climate runs for present climate conditions were examined and evaluated using Baltic Sea modelling. The results indicate that increased nutrient loads will not inhibit future Baltic Sea acidification; instead, the seasonal pH cycle will be amplified by increased biological production and mineralization. All examined scenarios indicate future acidification of the whole Baltic Sea that is insensitive to the chosen global climate model. The main factor controlling the direction and magnitude of future pH changes is atmospheric CO2 concentration (i.e. emissions). Climate change and land-derived changes (e.g. nutrient loads) affect acidification mainly by altering the seasonal cycle and deep-water conditions. Apart from decreasing pH, we also project a decreased saturation state of calcium carbonate, decreased respiration index and increasing hypoxic area _ all factors that will threaten the marine ecosystem. We demonstrate that substantial reductions in fossil-fuel burning are needed to minimise the coming pH decrease and that substantial reductions in nutrient loads are needed to reduce the coming increase in hypoxic and anoxic waters.
Original languageEnglish
Article number19586
Number of pages23
JournalTellus Series B: Chemical and Physical Meteorology
Volume64
Issue number1
DOIs
Publication statusPublished - 2012

Open Access - Access Right Statement

© 2012 A. Omstedt et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported License (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Keywords

  • Baltic Sea
  • climatic changes
  • eutrophication
  • ocean acidification

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