 |
| Titel |
Deep-convection events foster carbonate ion reduction in deep coral reefs |
| VerfasserIn |
Fiz F. Perez, Marcos Fontela, Maribel I. Garcia-Ibañez, Pascale Lherminier, Patricia Zunino, Mercedes de la Paz, Xose A. Padín, Fernando Alonso-Pérez, Anton Velo, Elisa F. Guallart, Herlé Mercier |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148528
|
| Publikation (Nr.) |
 EGU/EGU2017-12791.pdf |
|
|
|
|
|
| Zusammenfassung |
| Since millennial times, water mass circulation and deep-convection events have been
transforming warm upper waters at high latitudes into cold and well-oxygenated deep waters.
These processes have filled the deep North Atlantic Ocean with waters moderately saturated
in calcium carbonate, thus promoting the growth of stony corals, which are hotspots of
biodiversity. During the Anthropocene, the meridional circulation has been conveying
cumulative amounts of more acidified waters with lower calcium carbonate saturation levels
due to the incorporation of anthropogenic carbon dioxide, with very harsh conditions for
deep cold-water corals projected by 2100. We evaluate the diminution of calcium
carbonate saturation levels (aragonite form) due to the increase in anthropogenic carbon
dioxide during the last two decades (2002-2016). We observe a strong decrease in the
aragonite saturation levels concomitant with the reduction in the volume transport of
aragonite-saturated waters. We estimate a 30-35% reduction in the transport of ion carbonate
excess over the saturation levels with respect to the natural carbon cycle for the
period 2002-2016. This reduction is associated with an increase in the downward
transport of hydrogen ions. We also observe a heaving of the aragonite saturation
horizons during the last 25 years, which is estimated at 6 m year−1 for the deep waters
and 12-14 m year−1 for the intermediated waters. The harsh winters of 2015 and
2016 have fostered the fast addition of more acidified water into the lower layers of
the North Atlantic through deep-convection events. In the future scenario of 2oC
warming, the anthropogenic carbon dioxide in the water column would be double
than today and the associated transport of hydrogen ions towards the bottom water
would reduce the aragonite saturation levels to 60-80% with respect to preindustrial
levels. This reduction in the aragonite saturation levels would suppose a strong
diminution of the North Atlantic habitats where stony corals will be able to inhabit. |
|
|
|
|
|
|