Freshening of the labrador sea as a trigger for little ice age development
Arctic freshwater discharges to the Labrador Sea from melting glaciers and sea ice can have a large impact on ocean circulation dynamics in the North Atlantic, modifying climate and deep water formation in this region. In this study, we present for the first time a high resolution record of ice raft...
Published in: | Climate of the Past |
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Language: | English |
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Copernicus Gesellschaft Mbh
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Online Access: | http://hdl.handle.net/10400.1/11132 https://doi.org/10.5194/cp-13-317-2017 |
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ftunivalgarve:oai:sapientia.ualg.pt:10400.1/11132 2023-05-15T14:58:13+02:00 Freshening of the labrador sea as a trigger for little ice age development Alonso-Garcia, Montserrat Kleiven, Helga (Kikki) F. McManus, Jerry F. Moffa-Sanchez, Paola Broecker, Wallace S. Flower, Benjamin P. 2017-04 http://hdl.handle.net/10400.1/11132 https://doi.org/10.5194/cp-13-317-2017 eng eng Copernicus Gesellschaft Mbh info:eu-repo/grantAgreement/FCT/5876/147257/PT 1814-9324 1814-9332 http://hdl.handle.net/10400.1/11132 doi:10.5194/cp-13-317-2017 openAccess http://creativecommons.org/licenses/by/4.0/ CC-BY Subpolar North-Atlantic Last 2000 years Surface temperatures Climate variability Arctic oscillation Greenland shelf Circulation Holocene Iceland Ocean article 2017 ftunivalgarve https://doi.org/10.5194/cp-13-317-2017 2022-05-30T08:48:11Z Arctic freshwater discharges to the Labrador Sea from melting glaciers and sea ice can have a large impact on ocean circulation dynamics in the North Atlantic, modifying climate and deep water formation in this region. In this study, we present for the first time a high resolution record of ice rafting in the Labrador Sea over the last millennium to assess the effects of freshwater discharges in this region on ocean circulation and climate. The occurrence of ice-rafted debris (IRD) in the Labrador Sea was studied using sediments from Site GS06-144-03 (57.29 degrees N, 48.37 degrees W; 3432 m water depth). IRD from the fraction 63-150 mu m shows particularly high concentrations during the intervals similar to AD 1000-1100, similar to 1150-1250, similar to 1400-1450, similar to 1650-1700 and similar to 1750-1800. The first two intervals occurred during the Medieval Climate Anomaly (MCA), whereas the others took place within the Little Ice Age (LIA). Mineralogical identification indicates that the main IRD source during the MCA was SE Greenland. In contrast, the concentration and relative abundance of hematite-stained grains reflects an increase in the contribution of Arctic ice during the LIA. The comparison of our Labrador Sea IRD records with other climate proxies from the subpolar North Atlantic allowed us to propose a sequence of processes that led to the cooling that occurred during the LIA, particularly in the Northern Hemisphere. This study reveals that the warm cli- mate of the MCA may have enhanced iceberg calving along the SE Greenland coast and, as a result, freshened the subpolar gyre (SPG). Consequently, SPG circulation switched to a weaker mode and reduced convection in the Labrador Sea, decreasing its contribution to the North Atlantic deep water formation and, thus, reducing the amount of heat transported to high latitudes. This situation of weak SPG circulation may have made the North Atlantic climate more unstable, inducing a state in which external forcings (e.g. reduced solar irradiance and ... Article in Journal/Newspaper Arctic Greenland Iceberg* Iceland Labrador Sea North Atlantic Deep Water North Atlantic Sea ice Universidade do Algarve: Sapienta Arctic Greenland Climate of the Past 13 4 317 331 |
institution |
Open Polar |
collection |
Universidade do Algarve: Sapienta |
op_collection_id |
ftunivalgarve |
language |
English |
topic |
Subpolar North-Atlantic Last 2000 years Surface temperatures Climate variability Arctic oscillation Greenland shelf Circulation Holocene Iceland Ocean |
spellingShingle |
Subpolar North-Atlantic Last 2000 years Surface temperatures Climate variability Arctic oscillation Greenland shelf Circulation Holocene Iceland Ocean Alonso-Garcia, Montserrat Kleiven, Helga (Kikki) F. McManus, Jerry F. Moffa-Sanchez, Paola Broecker, Wallace S. Flower, Benjamin P. Freshening of the labrador sea as a trigger for little ice age development |
topic_facet |
Subpolar North-Atlantic Last 2000 years Surface temperatures Climate variability Arctic oscillation Greenland shelf Circulation Holocene Iceland Ocean |
description |
Arctic freshwater discharges to the Labrador Sea from melting glaciers and sea ice can have a large impact on ocean circulation dynamics in the North Atlantic, modifying climate and deep water formation in this region. In this study, we present for the first time a high resolution record of ice rafting in the Labrador Sea over the last millennium to assess the effects of freshwater discharges in this region on ocean circulation and climate. The occurrence of ice-rafted debris (IRD) in the Labrador Sea was studied using sediments from Site GS06-144-03 (57.29 degrees N, 48.37 degrees W; 3432 m water depth). IRD from the fraction 63-150 mu m shows particularly high concentrations during the intervals similar to AD 1000-1100, similar to 1150-1250, similar to 1400-1450, similar to 1650-1700 and similar to 1750-1800. The first two intervals occurred during the Medieval Climate Anomaly (MCA), whereas the others took place within the Little Ice Age (LIA). Mineralogical identification indicates that the main IRD source during the MCA was SE Greenland. In contrast, the concentration and relative abundance of hematite-stained grains reflects an increase in the contribution of Arctic ice during the LIA. The comparison of our Labrador Sea IRD records with other climate proxies from the subpolar North Atlantic allowed us to propose a sequence of processes that led to the cooling that occurred during the LIA, particularly in the Northern Hemisphere. This study reveals that the warm cli- mate of the MCA may have enhanced iceberg calving along the SE Greenland coast and, as a result, freshened the subpolar gyre (SPG). Consequently, SPG circulation switched to a weaker mode and reduced convection in the Labrador Sea, decreasing its contribution to the North Atlantic deep water formation and, thus, reducing the amount of heat transported to high latitudes. This situation of weak SPG circulation may have made the North Atlantic climate more unstable, inducing a state in which external forcings (e.g. reduced solar irradiance and ... |
format |
Article in Journal/Newspaper |
author |
Alonso-Garcia, Montserrat Kleiven, Helga (Kikki) F. McManus, Jerry F. Moffa-Sanchez, Paola Broecker, Wallace S. Flower, Benjamin P. |
author_facet |
Alonso-Garcia, Montserrat Kleiven, Helga (Kikki) F. McManus, Jerry F. Moffa-Sanchez, Paola Broecker, Wallace S. Flower, Benjamin P. |
author_sort |
Alonso-Garcia, Montserrat |
title |
Freshening of the labrador sea as a trigger for little ice age development |
title_short |
Freshening of the labrador sea as a trigger for little ice age development |
title_full |
Freshening of the labrador sea as a trigger for little ice age development |
title_fullStr |
Freshening of the labrador sea as a trigger for little ice age development |
title_full_unstemmed |
Freshening of the labrador sea as a trigger for little ice age development |
title_sort |
freshening of the labrador sea as a trigger for little ice age development |
publisher |
Copernicus Gesellschaft Mbh |
publishDate |
2017 |
url |
http://hdl.handle.net/10400.1/11132 https://doi.org/10.5194/cp-13-317-2017 |
geographic |
Arctic Greenland |
geographic_facet |
Arctic Greenland |
genre |
Arctic Greenland Iceberg* Iceland Labrador Sea North Atlantic Deep Water North Atlantic Sea ice |
genre_facet |
Arctic Greenland Iceberg* Iceland Labrador Sea North Atlantic Deep Water North Atlantic Sea ice |
op_relation |
info:eu-repo/grantAgreement/FCT/5876/147257/PT 1814-9324 1814-9332 http://hdl.handle.net/10400.1/11132 doi:10.5194/cp-13-317-2017 |
op_rights |
openAccess http://creativecommons.org/licenses/by/4.0/ |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/cp-13-317-2017 |
container_title |
Climate of the Past |
container_volume |
13 |
container_issue |
4 |
container_start_page |
317 |
op_container_end_page |
331 |
_version_ |
1766330297016647680 |