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...
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Online Access: | https://doi.org/10.5194/cp-13-317-2017 https://cp.copernicus.org/articles/13/317/2017/ |
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fttriple:oai:gotriple.eu:4Q6OArpcRWC3emiHWKuAM 2023-05-15T15:02:17+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. 2018-09-27 https://doi.org/10.5194/cp-13-317-2017 https://cp.copernicus.org/articles/13/317/2017/ en eng Copernicus Publications doi:10.5194/cp-13-317-2017 10670/1.a2sj7f 1814-9324 1814-9332 https://cp.copernicus.org/articles/13/317/2017/ undefined Geographica Helvetica - geography eISSN: 1814-9332 envir geo Text https://vocabularies.coar-repositories.org/resource_types/c_18cf/ Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2018 fttriple https://doi.org/10.5194/cp-13-317-2017 2023-01-22T17:39:16Z 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° N, 48.37° W; 3432 m water depth). IRD from the fraction 63–150 µm shows particularly high concentrations during the intervals ∼ AD 1000–1100, ∼ 1150–1250, ∼ 1400–1450, ∼ 1650–1700 and ∼ 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 climate 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 volcanic eruptions) could easily drive periods of severe cold ... Article in Journal/Newspaper Arctic Greenland Iceberg* Labrador Sea North Atlantic Deep Water North Atlantic Sea ice Unknown Arctic Greenland Climate of the Past 13 4 317 331 |
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envir geo 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 |
envir geo |
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° N, 48.37° W; 3432 m water depth). IRD from the fraction 63–150 µm shows particularly high concentrations during the intervals ∼ AD 1000–1100, ∼ 1150–1250, ∼ 1400–1450, ∼ 1650–1700 and ∼ 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 climate 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 volcanic eruptions) could easily drive periods of severe cold ... |
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 Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/cp-13-317-2017 https://cp.copernicus.org/articles/13/317/2017/ |
geographic |
Arctic Greenland |
geographic_facet |
Arctic Greenland |
genre |
Arctic Greenland Iceberg* Labrador Sea North Atlantic Deep Water North Atlantic Sea ice |
genre_facet |
Arctic Greenland Iceberg* Labrador Sea North Atlantic Deep Water North Atlantic Sea ice |
op_source |
Geographica Helvetica - geography eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-13-317-2017 10670/1.a2sj7f 1814-9324 1814-9332 https://cp.copernicus.org/articles/13/317/2017/ |
op_rights |
undefined |
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 |
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1766334252971982848 |