EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Rising carbon dioxide concentrations in Swedish groundwater during 1980−2020

Marcus Klaus1,2
Marcus Klaus
  • 1Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden (
  • 2Department of Ecosystem Trace Gas Exchange, Global Change Research Institute of the Czech Academy of Sciences, Brno, Czech Republic (

Groundwater is one of the largest continental carbon reservoirs and tightly linked to globally significant carbon fluxes such as uptake on land, evasion from inland waters and delivery to oceans. Despite emerging evidence that these fluxes are sensitive to environmental changes, long-term trends in groundwater carbon dynamics remain widely unknown. Here I show that dissolved inorganic carbon and carbon dioxide concentrations in groundwater have increased on average by 29% and 48%, respectively, across Sweden (55−68°N) during 1980−2020. I attribute these changes mainly to a partial recovery from historic atmospheric sulfate deposition and associated shifts in weathering pathways in acid-sensitive bedrock, but also to enhanced soil respiration as a likely consequence of climate and land use changes. The results highlight previously neglected significant long-term and large-scale dynamics in groundwater carbon cycling and have implications for the pathways and time scales through which carbon is cycled through the land - inland water - ocean continuum. The observed dynamics should be included in carbon cycle models for accurate evaluations and predictions of the effects of environmental changes on regional and global carbon fluxes.

How to cite: Klaus, M.: Rising carbon dioxide concentrations in Swedish groundwater during 1980−2020, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-1265,, 2023.