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| Titel |
Impact of geoengineering with olivine dissolution on the carbon cycle and marine biology |
| VerfasserIn |
P. Köhler, J. Abrams, C. Völker, D. A. Wolf-Gladrow, J. Hartmann |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250063037
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| Zusammenfassung |
| We investigate the potential of a specific geoengineering technique: the carbon sequestration
by artificially enhanced silicate weathering via the dissolution of olivine. This approach
would not only operate against rising temperatures but would also oppose ocean acidification.
If details of the marine chemistry are taken into consideration, a new mass ratio of CO2
sequestration per olivine dissolution of about 1 is achieved, 20% smaller than previously
assumed. We calculate that this approach has the potential to sequestrate up to 1 Pg of C per
year directly, if olivine is distributed as fine powder over land areas of the humid
tropics, but this rate is limited by the saturation concentration of silicic acid. These
upper limit sequestration rates come at the environmental cost of pH values in the
rivers rising to 8.2 in examples for the rivers Amazon and Congo (Köhler et al.,
2010).
The secondary effects of the input of silicic acid connected with this approach leads in an
ecosystem model (ReCOM2.0 in MITgcm) to species shifts aways from the calcifying
species towards diatoms, thus altering the biological carbon pumps. Open ocean dissolution
of olivine would sequestrate about 1 Pg CO2 per Pg olivine from which about 8% are caused
by changes in the biological pumps (increase export of organic matter, decreased export of
CaCO3). The chemical impact of open ocean dissolution of olivine (the increased alkalinity
input) is therefore less efficient than dissolution on land, but leads due to different
chemical impacts to a higher surface ocean pH enhancement to counteract ocean
acidification. We finally investigate open ocean dissolution rates of up to 10 Pg olivine
per year corresponding to geoengineering rates which might be of interest in the
light of expected future emission (e.g. A2 scenario with emissions rising to 30
PgC/yr in 2100 AD). Those rates would still sequestrate only less than 20% of
the emission until 2100, but would require that the nowadays available shipping
capacity of tankers and bulk carriers is entirely used for olivine dissolution ten times a
year.
Reference
Köhler, P.; Hartmann, J. and Wolf-Gladrow, D. A. (2010) Geoengineering potential of
artificially enhanced silicate weathering of olivine, Proceedings of the National Academy of
Science 107, 20228-20233, doi: 10.1073/pnas.1000545107. |
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