The impact of meltwater discharge from the Greenland ice sheet on the Atlantic nutrient supply to the northwest European shelf
Projected future shoaling of the wintertime mixed layer in the northeast (NE) Atlantic has been shown to induce a regime shift in the main nutrient supply pathway from the Atlantic to the northwest European shelf (NWES) near the end of the 21st century. While reduced winter convection leads to a sub...
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ftcopernicus:oai:publications.copernicus.org:os79977 2023-05-15T16:28:43+02:00 The impact of meltwater discharge from the Greenland ice sheet on the Atlantic nutrient supply to the northwest European shelf Mathis, Moritz Mikolajewicz, Uwe 2020-01-27 application/pdf https://doi.org/10.5194/os-16-167-2020 https://os.copernicus.org/articles/16/167/2020/ eng eng doi:10.5194/os-16-167-2020 https://os.copernicus.org/articles/16/167/2020/ eISSN: 1812-0792 Text 2020 ftcopernicus https://doi.org/10.5194/os-16-167-2020 2020-07-20T16:22:28Z Projected future shoaling of the wintertime mixed layer in the northeast (NE) Atlantic has been shown to induce a regime shift in the main nutrient supply pathway from the Atlantic to the northwest European shelf (NWES) near the end of the 21st century. While reduced winter convection leads to a substantial decrease in the vertical nutrient supply and biological productivity in the open ocean, vertical mixing processes at the shelf break maintain a connection to the subpycnocline nutrient pool and thus productivity on the shelf. Here, we investigate how meltwater discharge from the Greenland ice sheet (GIS), not yet taken into account, impacts the mixed layer shoaling and the regime shift in terms of spatial distribution and temporal variability. To this end, we have downscaled sensitivity experiments by a global Earth system model for various GIS melting rates with a regionally coupled ocean–atmosphere climate system model. The model results indicate that increasing GIS meltwater discharge leads to a general intensification of the regime shift. Atlantic subpycnocline water masses mixed up at the shelf break become richer in nutrients and thus further limit the projected nutrient decline on the shelf. Moreover, the stronger vertical nutrient gradient through the pycnocline results in an enhanced interannual variability of on-shelf nutrient fluxes which, however, do not significantly increase variations in nutrient concentrations and primary production on the shelf. Due to the impact of the GIS meltwater discharge on the NE Atlantic mixed layer depth, the regime shift becomes initiated earlier in the century. The effect on the onset timing, though, is found to be strongly damped by the weakening of the Atlantic meridional overturning circulation. A GIS melting rate that is even 10 times higher than expected for emission scenario Representative Concentration Pathway (RCP) 8.5 would not lead to an onset of the regime shift until the 2070s. Text Greenland Ice Sheet Copernicus Publications: E-Journals Greenland Ocean Science 16 1 167 193 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Projected future shoaling of the wintertime mixed layer in the northeast (NE) Atlantic has been shown to induce a regime shift in the main nutrient supply pathway from the Atlantic to the northwest European shelf (NWES) near the end of the 21st century. While reduced winter convection leads to a substantial decrease in the vertical nutrient supply and biological productivity in the open ocean, vertical mixing processes at the shelf break maintain a connection to the subpycnocline nutrient pool and thus productivity on the shelf. Here, we investigate how meltwater discharge from the Greenland ice sheet (GIS), not yet taken into account, impacts the mixed layer shoaling and the regime shift in terms of spatial distribution and temporal variability. To this end, we have downscaled sensitivity experiments by a global Earth system model for various GIS melting rates with a regionally coupled ocean–atmosphere climate system model. The model results indicate that increasing GIS meltwater discharge leads to a general intensification of the regime shift. Atlantic subpycnocline water masses mixed up at the shelf break become richer in nutrients and thus further limit the projected nutrient decline on the shelf. Moreover, the stronger vertical nutrient gradient through the pycnocline results in an enhanced interannual variability of on-shelf nutrient fluxes which, however, do not significantly increase variations in nutrient concentrations and primary production on the shelf. Due to the impact of the GIS meltwater discharge on the NE Atlantic mixed layer depth, the regime shift becomes initiated earlier in the century. The effect on the onset timing, though, is found to be strongly damped by the weakening of the Atlantic meridional overturning circulation. A GIS melting rate that is even 10 times higher than expected for emission scenario Representative Concentration Pathway (RCP) 8.5 would not lead to an onset of the regime shift until the 2070s. |
format |
Text |
author |
Mathis, Moritz Mikolajewicz, Uwe |
spellingShingle |
Mathis, Moritz Mikolajewicz, Uwe The impact of meltwater discharge from the Greenland ice sheet on the Atlantic nutrient supply to the northwest European shelf |
author_facet |
Mathis, Moritz Mikolajewicz, Uwe |
author_sort |
Mathis, Moritz |
title |
The impact of meltwater discharge from the Greenland ice sheet on the Atlantic nutrient supply to the northwest European shelf |
title_short |
The impact of meltwater discharge from the Greenland ice sheet on the Atlantic nutrient supply to the northwest European shelf |
title_full |
The impact of meltwater discharge from the Greenland ice sheet on the Atlantic nutrient supply to the northwest European shelf |
title_fullStr |
The impact of meltwater discharge from the Greenland ice sheet on the Atlantic nutrient supply to the northwest European shelf |
title_full_unstemmed |
The impact of meltwater discharge from the Greenland ice sheet on the Atlantic nutrient supply to the northwest European shelf |
title_sort |
impact of meltwater discharge from the greenland ice sheet on the atlantic nutrient supply to the northwest european shelf |
publishDate |
2020 |
url |
https://doi.org/10.5194/os-16-167-2020 https://os.copernicus.org/articles/16/167/2020/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_source |
eISSN: 1812-0792 |
op_relation |
doi:10.5194/os-16-167-2020 https://os.copernicus.org/articles/16/167/2020/ |
op_doi |
https://doi.org/10.5194/os-16-167-2020 |
container_title |
Ocean Science |
container_volume |
16 |
container_issue |
1 |
container_start_page |
167 |
op_container_end_page |
193 |
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1766018399636291584 |