Ocean biogeochemistry in the warm climate of the late Paleocene
The late Paleocene is characterized by warm and stable climatic conditions that served as the background climate for the Paleocene–Eocene Thermal Maximum (PETM, ~55 million years ago). With respect to feedback processes in the carbon cycle, the ocean biogeochemical background state is of major impor...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-01-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/11/63/2015/cp-11-63-2015.pdf |
| _version_ | 1818509451324293120 |
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| author | M. Heinze T. Ilyina |
| author_facet | M. Heinze T. Ilyina |
| author_sort | M. Heinze |
| collection | DOAJ |
| description | The late Paleocene is characterized by warm and stable climatic conditions
that served as the background climate for the Paleocene–Eocene Thermal
Maximum (PETM, ~55 million years ago). With respect to feedback
processes in the carbon cycle, the ocean biogeochemical background state is
of major importance for projecting the climatic response to a carbon
perturbation related to the PETM. Therefore, we use the Hamburg Ocean Carbon
Cycle model (HAMOCC), embedded in the ocean general circulation model of the
Max Planck Institute for Meteorology, MPIOM, to constrain the ocean
biogeochemistry of the late Paleocene. We focus on the evaluation of modeled
spatial and vertical distributions of the ocean carbon cycle parameters in a
long-term warm steady-state ocean, based on a 560 ppm CO<sub>2</sub> atmosphere.
Model results are discussed in the context of available proxy data and
simulations of pre-industrial conditions. Our results illustrate that ocean
biogeochemistry is shaped by the warm and sluggish ocean state of the late
Paleocene. Primary production is slightly reduced in comparison to the
present day; it is intensified along the Equator, especially in the Atlantic.
This enhances remineralization of organic matter, resulting in strong oxygen
minimum zones and CaCO<sub>3</sub> dissolution in intermediate waters. We show that
an equilibrium CO<sub>2</sub> exchange without increasing total alkalinity
concentrations above today's values is achieved. However, consistent with the
higher atmospheric CO<sub>2</sub>, the surface ocean pH and the saturation state with
respect to CaCO<sub>3</sub> are lower than today. Our results indicate that, under
such conditions, the surface ocean carbonate chemistry is expected to be more
sensitive to a carbon perturbation (i.e., the PETM) due to lower CO<sub>3</sub><sup>2−</sup>
concentration, whereas the deep ocean calcite sediments would be less
vulnerable to dissolution due to the vertically stratified ocean. |
| first_indexed | 2024-12-10T22:45:38Z |
| format | Article |
| id | doaj.art-f682d547a73140469fad28c209ac6660 |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-12-10T22:45:38Z |
| publishDate | 2015-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-f682d547a73140469fad28c209ac66602022-12-22T01:30:35ZengCopernicus PublicationsClimate of the Past1814-93241814-93322015-01-01111637910.5194/cp-11-63-2015Ocean biogeochemistry in the warm climate of the late PaleoceneM. Heinze0T. Ilyina1Max Planck Institute for Meteorology, Bundesstrasse 53, 20146 Hamburg, GermanyMax Planck Institute for Meteorology, Bundesstrasse 53, 20146 Hamburg, GermanyThe late Paleocene is characterized by warm and stable climatic conditions that served as the background climate for the Paleocene–Eocene Thermal Maximum (PETM, ~55 million years ago). With respect to feedback processes in the carbon cycle, the ocean biogeochemical background state is of major importance for projecting the climatic response to a carbon perturbation related to the PETM. Therefore, we use the Hamburg Ocean Carbon Cycle model (HAMOCC), embedded in the ocean general circulation model of the Max Planck Institute for Meteorology, MPIOM, to constrain the ocean biogeochemistry of the late Paleocene. We focus on the evaluation of modeled spatial and vertical distributions of the ocean carbon cycle parameters in a long-term warm steady-state ocean, based on a 560 ppm CO<sub>2</sub> atmosphere. Model results are discussed in the context of available proxy data and simulations of pre-industrial conditions. Our results illustrate that ocean biogeochemistry is shaped by the warm and sluggish ocean state of the late Paleocene. Primary production is slightly reduced in comparison to the present day; it is intensified along the Equator, especially in the Atlantic. This enhances remineralization of organic matter, resulting in strong oxygen minimum zones and CaCO<sub>3</sub> dissolution in intermediate waters. We show that an equilibrium CO<sub>2</sub> exchange without increasing total alkalinity concentrations above today's values is achieved. However, consistent with the higher atmospheric CO<sub>2</sub>, the surface ocean pH and the saturation state with respect to CaCO<sub>3</sub> are lower than today. Our results indicate that, under such conditions, the surface ocean carbonate chemistry is expected to be more sensitive to a carbon perturbation (i.e., the PETM) due to lower CO<sub>3</sub><sup>2−</sup> concentration, whereas the deep ocean calcite sediments would be less vulnerable to dissolution due to the vertically stratified ocean.http://www.clim-past.net/11/63/2015/cp-11-63-2015.pdf |
| spellingShingle | M. Heinze T. Ilyina Ocean biogeochemistry in the warm climate of the late Paleocene Climate of the Past |
| title | Ocean biogeochemistry in the warm climate of the late Paleocene |
| title_full | Ocean biogeochemistry in the warm climate of the late Paleocene |
| title_fullStr | Ocean biogeochemistry in the warm climate of the late Paleocene |
| title_full_unstemmed | Ocean biogeochemistry in the warm climate of the late Paleocene |
| title_short | Ocean biogeochemistry in the warm climate of the late Paleocene |
| title_sort | ocean biogeochemistry in the warm climate of the late paleocene |
| url | http://www.clim-past.net/11/63/2015/cp-11-63-2015.pdf |
| work_keys_str_mv | AT mheinze oceanbiogeochemistryinthewarmclimateofthelatepaleocene AT tilyina oceanbiogeochemistryinthewarmclimateofthelatepaleocene |