Joint Seminar: Impact of volcanic eruptions on the marine carbon cycle

The impact of volcanic eruptions on climate and the global carbon cycle is investigated with three model experiments, with a focus on the marine carbon cycle. First, possible impact routes of volcanic eruptions are layed out. For example, an increase of solubility of CO2 in the ocean may be caused by a temperature decrease of the sea water in response to reduced incoming radiation. Non-linear interactions with the perturbed oceanic and atmospheric circulation will change the nutrient distribution and hence marine biological production. On a more local scale, the leaching of nutrients from volcanic ash has the potential to stimulate additional phytoplankton growth, while reduced short wave radiation would potentially limit it. In summary, we try to address three issues: i) to what extent have observed past variabilities of atmospheric pCO2 been caused by volcanic eruptions?, ii) can recent variations in airborne fraction of anthropogenic CO2 be explained by ocean fertilization from volcanic ash?, and iii) are supervolcanic eruptions like the 70,000 b.p Yellowstone principally different from smaller -Pinatubo like- eruptions?

A set of three model set-ups is used to investigate the above.  In one experiment, known as the Millennium experiment, volcanic eruptions are represented as radiation perturbations in an Earth System Model (MPI-ESM). In a second set-up, ash deposition from the Pinatubo and Cerro Hudson volcanic eruptions (both in 1991) is first calculated with ECHAM-HAM, and then used to force a biogeochemical ocean model (MPIOM-HAMOCC). In a third set-up, a so-called super-eruption is simulated with the MPI-ESM with forcing obtained from ECHAM-HAM. In case one a 5-member ensemble, and in case three a 15-member ensemble is used to address internal variability of the system.




15:15 h


Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg


Joachim Segschneider, MPI-M


Zoltan Szuts

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