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| Titel |
Can a melting Greenland ice sheet act as a nutrient source that compensates projected nutrient deficits in Atlantic surface water masses? |
| VerfasserIn |
Christian Rodehacke, Matthias Gröger |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250092090
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| Publikation (Nr.) |
 EGU/EGU2014-6415.pdf |
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| Zusammenfassung |
| Numerous studies have shown that under severe climate warming the northern Atlantic Ocean
is more stratified, because an enhanced hydrological cycle and warming of upper ocean layers
hampers water mass exchange with deeper layers. Therefore the supply of nutrient-rich deep
water masses, which replenish the nutrients in the photic zone, is weakened in many climate
warming scenarios. Consequently biological activities in the photic zone are stronger limited
by the availability of nutrients. On the other side several studies, addressing in
particular the release of organic material from melting glaciers or outlet glaciers of
Greenland, suggest that intensified melting of glaciers and ice sheet might impact the
nutrient supply to the ocean. This leads to the question: Does a strongly melting
Greenland ice sheet can compensate the restrained nutrient supply from deep water
masses?
We’ve performed simulations with the MPI-ESM under different scenarios to address the
question. A run under pre-industrial conditions serves as a base line experiment, while
simulations under the strong warming scenario RCP8.5 shall represent the conditions in a
warming world. To mimic the influence of a melting Greenland ice sheet, we discharge
homogenously 0.1 Sv (105 m3/s) of fresh water along the coast of Greenland for 40 years.
The continuous discharge of 0.1 Sv comes from common hosing experiments, while the setup
with the uniformly release along the coast follows two comprehensive studies about
the melting water influence on the Atlantic Meridional Overturning Circulation
(AMOC) under historical and future warming conditions (RCP8.5). Proportional to
the melting strength, nutrients (NO3, PO4, SiO2, and Iron) have been released,
whereby the proportionalities have been compiled from a range of published values.
In terms of release concentration a high end and a conservative setup have been
analyzed.
The simulations highlight, that the additionally released nutrients, have indeed a
significant impact on the nutrient distribution. The nutrients flow with the general circulation
from the coastal areas of Greenland into the Labrador Sea and spread afterwards into the
North Atlantic. In particular the primary production is much stronger than in scenarios where
meltwaters have been released without nutrients. All in all it seems, that even in the
here assumed high nutrient supply scenarios the loss of nutrients due to increased
stratification cannot be compensated for by nutrient input of a melting Greenland ice
sheet. |
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