Winter–spring warming in the North Atlantic during the last 2000 years: evidence from southwest Iceland
Temperature reconstructions from the Northern Hemisphere (NH) generally indicate cooling over the Holocene, which is often attributed to decreasing summer insolation. However, climate model simulations predict that rising atmospheric CO 2 concentrations and the collapse of the Laurentide Ice Sheet c...
Published in: | Climate of the Past |
---|---|
Main Authors: | , , , |
Format: | Text |
Language: | English |
Published: |
2021
|
Subjects: | |
Online Access: | https://doi.org/10.5194/cp-17-1363-2021 https://cp.copernicus.org/articles/17/1363/2021/ |
id |
ftcopernicus:oai:publications.copernicus.org:cp86415 |
---|---|
record_format |
openpolar |
spelling |
ftcopernicus:oai:publications.copernicus.org:cp86415 2023-05-15T16:41:24+02:00 Winter–spring warming in the North Atlantic during the last 2000 years: evidence from southwest Iceland Richter, Nora Russell, James M. Garfinkel, Johanna Huang, Yongsong 2021-06-22 application/pdf https://doi.org/10.5194/cp-17-1363-2021 https://cp.copernicus.org/articles/17/1363/2021/ eng eng doi:10.5194/cp-17-1363-2021 https://cp.copernicus.org/articles/17/1363/2021/ eISSN: 1814-9332 Text 2021 ftcopernicus https://doi.org/10.5194/cp-17-1363-2021 2021-06-28T16:22:14Z Temperature reconstructions from the Northern Hemisphere (NH) generally indicate cooling over the Holocene, which is often attributed to decreasing summer insolation. However, climate model simulations predict that rising atmospheric CO 2 concentrations and the collapse of the Laurentide Ice Sheet caused mean annual warming during this epoch. This contrast could reflect a seasonal bias in temperature proxies, and particularly a lack of proxies that record cold (late fall–early spring) season temperatures, or inaccuracies in climate model predictions of NH temperature. We reconstructed winter–spring temperatures during the Common Era (i.e., the last 2000 years) using alkenones, lipids produced by Isochrysidales haptophyte algae that bloom during spring ice-out, preserved in sediments from Vestra Gíslholtsvatn (VGHV), southwest Iceland. Our record indicates that winter–spring temperatures warmed during the last 2000 years, in contrast to most NH averages. Sensitivity tests with a lake energy balance model suggest that warmer winter and spring air temperatures result in earlier ice-out dates and warmer spring lake water temperatures and therefore warming in our proxy record. Regional air temperatures are strongly influenced by sea surface temperatures during the winter and spring season. Sea surface temperatures (SSTs) respond to both changes in ocean circulation and gradual changes in insolation. We also found distinct seasonal differences in centennial-scale, cold-season temperature variations in VGHV compared to existing records of summer and annual temperatures from Iceland. Multi-decadal to centennial-scale changes in winter–spring temperatures were strongly modulated by internal climate variability and changes in regional ocean circulation, which can result in winter and spring warming in Iceland even after a major negative radiative perturbation. Text Ice Sheet Iceland North Atlantic Copernicus Publications: E-Journals Climate of the Past 17 3 1363 1383 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Temperature reconstructions from the Northern Hemisphere (NH) generally indicate cooling over the Holocene, which is often attributed to decreasing summer insolation. However, climate model simulations predict that rising atmospheric CO 2 concentrations and the collapse of the Laurentide Ice Sheet caused mean annual warming during this epoch. This contrast could reflect a seasonal bias in temperature proxies, and particularly a lack of proxies that record cold (late fall–early spring) season temperatures, or inaccuracies in climate model predictions of NH temperature. We reconstructed winter–spring temperatures during the Common Era (i.e., the last 2000 years) using alkenones, lipids produced by Isochrysidales haptophyte algae that bloom during spring ice-out, preserved in sediments from Vestra Gíslholtsvatn (VGHV), southwest Iceland. Our record indicates that winter–spring temperatures warmed during the last 2000 years, in contrast to most NH averages. Sensitivity tests with a lake energy balance model suggest that warmer winter and spring air temperatures result in earlier ice-out dates and warmer spring lake water temperatures and therefore warming in our proxy record. Regional air temperatures are strongly influenced by sea surface temperatures during the winter and spring season. Sea surface temperatures (SSTs) respond to both changes in ocean circulation and gradual changes in insolation. We also found distinct seasonal differences in centennial-scale, cold-season temperature variations in VGHV compared to existing records of summer and annual temperatures from Iceland. Multi-decadal to centennial-scale changes in winter–spring temperatures were strongly modulated by internal climate variability and changes in regional ocean circulation, which can result in winter and spring warming in Iceland even after a major negative radiative perturbation. |
format |
Text |
author |
Richter, Nora Russell, James M. Garfinkel, Johanna Huang, Yongsong |
spellingShingle |
Richter, Nora Russell, James M. Garfinkel, Johanna Huang, Yongsong Winter–spring warming in the North Atlantic during the last 2000 years: evidence from southwest Iceland |
author_facet |
Richter, Nora Russell, James M. Garfinkel, Johanna Huang, Yongsong |
author_sort |
Richter, Nora |
title |
Winter–spring warming in the North Atlantic during the last 2000 years: evidence from southwest Iceland |
title_short |
Winter–spring warming in the North Atlantic during the last 2000 years: evidence from southwest Iceland |
title_full |
Winter–spring warming in the North Atlantic during the last 2000 years: evidence from southwest Iceland |
title_fullStr |
Winter–spring warming in the North Atlantic during the last 2000 years: evidence from southwest Iceland |
title_full_unstemmed |
Winter–spring warming in the North Atlantic during the last 2000 years: evidence from southwest Iceland |
title_sort |
winter–spring warming in the north atlantic during the last 2000 years: evidence from southwest iceland |
publishDate |
2021 |
url |
https://doi.org/10.5194/cp-17-1363-2021 https://cp.copernicus.org/articles/17/1363/2021/ |
genre |
Ice Sheet Iceland North Atlantic |
genre_facet |
Ice Sheet Iceland North Atlantic |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-17-1363-2021 https://cp.copernicus.org/articles/17/1363/2021/ |
op_doi |
https://doi.org/10.5194/cp-17-1363-2021 |
container_title |
Climate of the Past |
container_volume |
17 |
container_issue |
3 |
container_start_page |
1363 |
op_container_end_page |
1383 |
_version_ |
1766031823606906880 |