Heinrich events show two-stage climate response in transient glacial simulations
<p>Heinrich events are among the dominant modes of glacial climate variability. During these events, massive iceberg armadas were released by the Laurentide Ice Sheet and sailed across the Atlantic where they melted and released freshwater, as well as detritus, that formed characteristic lay...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2019-01-01
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| Series: | Climate of the Past |
| Online Access: | https://www.clim-past.net/15/153/2019/cp-15-153-2019.pdf |
| _version_ | 1819160851340328960 |
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| author | F. A. Ziemen M.-L. Kapsch M. Klockmann U. Mikolajewicz |
| author_facet | F. A. Ziemen M.-L. Kapsch M. Klockmann U. Mikolajewicz |
| author_sort | F. A. Ziemen |
| collection | DOAJ |
| description | <p>Heinrich events are among the dominant modes of glacial climate variability.
During these events, massive iceberg armadas were released by the Laurentide
Ice Sheet and sailed across the Atlantic where they melted and released freshwater, as well as detritus, that formed characteristic layers on the seafloor. Heinrich events are known for cold climates in the North Atlantic
region and global climate changes. We study these events in a fully coupled
complex ice sheet–climate model with synchronous coupling between ice sheets
and oceans. The ice discharges occur as an internal variability of the model
with a recurrence period of 5 kyr, an event duration of 1–1.5 kyr, and a
peak discharge rate of about 50 mSv, roughly consistent with
reconstructions. The climate response shows a two-stage behavior, with
freshwater release effects dominating the surge phase and ice sheet elevation
effects dominating the post-surge phase. As a direct response to the
freshwater discharge during the surge phase, deepwater formation in the
North Atlantic decreases and the North Atlantic deepwater cell weakens by
3.5 Sv. With the reduced oceanic heat transport, the surface temperatures
across the North Atlantic decrease, and the associated reduction in
evaporation causes a drying in Europe. The ice discharge lowers the surface
elevation in the Hudson Bay area and thus leads to increased precipitation
and accelerated ice sheet regrowth in the post-surge phase. Furthermore, the
jet stream widens to the north, which contributes to a weakening of the
subpolar gyre and a continued cooling over Europe even after the ice
discharge. This two-stage behavior can explain previously contradicting model
results and understandings of Heinrich events.</p> |
| first_indexed | 2024-12-22T17:03:01Z |
| format | Article |
| id | doaj.art-be54389efa77464297a22502fb22b369 |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-12-22T17:03:01Z |
| publishDate | 2019-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-be54389efa77464297a22502fb22b3692022-12-21T18:19:18ZengCopernicus PublicationsClimate of the Past1814-93241814-93322019-01-011515316810.5194/cp-15-153-2019Heinrich events show two-stage climate response in transient glacial simulationsF. A. Ziemen0M.-L. Kapsch1M. Klockmann2U. Mikolajewicz3Max Planck Institute for Meteorology, Bundesstraße 53, 20146 Hamburg, GermanyMax Planck Institute for Meteorology, Bundesstraße 53, 20146 Hamburg, GermanyMax Planck Institute for Meteorology, Bundesstraße 53, 20146 Hamburg, GermanyMax Planck Institute for Meteorology, Bundesstraße 53, 20146 Hamburg, Germany<p>Heinrich events are among the dominant modes of glacial climate variability. During these events, massive iceberg armadas were released by the Laurentide Ice Sheet and sailed across the Atlantic where they melted and released freshwater, as well as detritus, that formed characteristic layers on the seafloor. Heinrich events are known for cold climates in the North Atlantic region and global climate changes. We study these events in a fully coupled complex ice sheet–climate model with synchronous coupling between ice sheets and oceans. The ice discharges occur as an internal variability of the model with a recurrence period of 5 kyr, an event duration of 1–1.5 kyr, and a peak discharge rate of about 50 mSv, roughly consistent with reconstructions. The climate response shows a two-stage behavior, with freshwater release effects dominating the surge phase and ice sheet elevation effects dominating the post-surge phase. As a direct response to the freshwater discharge during the surge phase, deepwater formation in the North Atlantic decreases and the North Atlantic deepwater cell weakens by 3.5 Sv. With the reduced oceanic heat transport, the surface temperatures across the North Atlantic decrease, and the associated reduction in evaporation causes a drying in Europe. The ice discharge lowers the surface elevation in the Hudson Bay area and thus leads to increased precipitation and accelerated ice sheet regrowth in the post-surge phase. Furthermore, the jet stream widens to the north, which contributes to a weakening of the subpolar gyre and a continued cooling over Europe even after the ice discharge. This two-stage behavior can explain previously contradicting model results and understandings of Heinrich events.</p>https://www.clim-past.net/15/153/2019/cp-15-153-2019.pdf |
| spellingShingle | F. A. Ziemen M.-L. Kapsch M. Klockmann U. Mikolajewicz Heinrich events show two-stage climate response in transient glacial simulations Climate of the Past |
| title | Heinrich events show two-stage climate response in transient glacial simulations |
| title_full | Heinrich events show two-stage climate response in transient glacial simulations |
| title_fullStr | Heinrich events show two-stage climate response in transient glacial simulations |
| title_full_unstemmed | Heinrich events show two-stage climate response in transient glacial simulations |
| title_short | Heinrich events show two-stage climate response in transient glacial simulations |
| title_sort | heinrich events show two stage climate response in transient glacial simulations |
| url | https://www.clim-past.net/15/153/2019/cp-15-153-2019.pdf |
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