Summer surface air temperature proxies point to near-sea-ice-free conditions in the Arctic at 127 ka

The Last Interglacial (LIG) period, which had higher summer solar insolation than today, has been suggested as the last time that Arctic summers were ice free. However, the latest suite of Coupled Modelling Intercomparison Project 6 Paleoclimate (CMIP6-PMIP4) simulations of the LIG produce a wide ra...

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Published in:Climate of the Past
Main Authors: L. C. Sime, R. Sivankutty, I. Vallet-Malmierca, A. M. de Boer, M. Sicard
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2023
Subjects:
Online Access:https://doi.org/10.5194/cp-19-883-2023
https://doaj.org/article/8572c7308d2e49b485f55b9faeb73f5a
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spelling ftdoajarticles:oai:doaj.org/article:8572c7308d2e49b485f55b9faeb73f5a 2023-06-11T04:08:47+02:00 Summer surface air temperature proxies point to near-sea-ice-free conditions in the Arctic at 127 ka L. C. Sime R. Sivankutty I. Vallet-Malmierca A. M. de Boer M. Sicard 2023-05-01T00:00:00Z https://doi.org/10.5194/cp-19-883-2023 https://doaj.org/article/8572c7308d2e49b485f55b9faeb73f5a EN eng Copernicus Publications https://cp.copernicus.org/articles/19/883/2023/cp-19-883-2023.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 doi:10.5194/cp-19-883-2023 1814-9324 1814-9332 https://doaj.org/article/8572c7308d2e49b485f55b9faeb73f5a Climate of the Past, Vol 19, Pp 883-900 (2023) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2023 ftdoajarticles https://doi.org/10.5194/cp-19-883-2023 2023-05-07T00:34:41Z The Last Interglacial (LIG) period, which had higher summer solar insolation than today, has been suggested as the last time that Arctic summers were ice free. However, the latest suite of Coupled Modelling Intercomparison Project 6 Paleoclimate (CMIP6-PMIP4) simulations of the LIG produce a wide range of Arctic summer minimum sea ice area (SIA) results, with a 30 % to 96 % reduction from the pre-industrial (PI) period. Sea ice proxies are also currently neither abundant nor consistent enough to determine the most realistic state. Here we estimate LIG minimum SIA indirectly through the use of 21 proxy records for LIG summer surface air temperature (SSAT) and 11 CMIP6-PMIP4 models for the LIG. We use two approaches. First, we use two tests to determine how skilful models are at simulating reconstructed Δ SSAT from proxy records (where Δ refers to LIG-PI). This identifies a positive correlation between model skill and the magnitude of Δ SIA: the most reliable models simulate a larger sea ice reduction. Averaging the two most skilful models yields an average SIA of 1.3×10 6 km 2 for the LIG. This equates to a 4.5×10 6 km 2 or 79 % SIA reduction from the PI to the LIG. Second, across the 11 models, the averaged Δ SSAT at the 21 proxy locations and the pan-Arctic average Δ SSAT are inversely correlated with Δ SIA ( r = - 0.86 <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="49pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="9657313141bbfae45c345d44f0c9138f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-19-883-2023-ie00001.svg" width="49pt" height="10pt" src="cp-19-883-2023-ie00001.png"/></svg:svg> and −0.79 , respectively). In other words, the models show that a larger Arctic warming is associated with a greater sea ice reduction. Using the proxy-record-averaged Δ SSAT of 4.5±1.7 K and the relationship between Δ SSAT and Δ SIA suggests an estimated sea ice reduction of 4.2 ± 1.4 × 10 6 <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="72pt" ... Article in Journal/Newspaper Arctic Sea ice Directory of Open Access Journals: DOAJ Articles Arctic Climate of the Past 19 4 883 900
institution Open Polar
collection Directory of Open Access Journals: DOAJ Articles
op_collection_id ftdoajarticles
language English
topic Environmental pollution
TD172-193.5
Environmental protection
TD169-171.8
Environmental sciences
GE1-350
spellingShingle Environmental pollution
TD172-193.5
Environmental protection
TD169-171.8
Environmental sciences
GE1-350
L. C. Sime
R. Sivankutty
I. Vallet-Malmierca
A. M. de Boer
M. Sicard
Summer surface air temperature proxies point to near-sea-ice-free conditions in the Arctic at 127 ka
topic_facet Environmental pollution
TD172-193.5
Environmental protection
TD169-171.8
Environmental sciences
GE1-350
description The Last Interglacial (LIG) period, which had higher summer solar insolation than today, has been suggested as the last time that Arctic summers were ice free. However, the latest suite of Coupled Modelling Intercomparison Project 6 Paleoclimate (CMIP6-PMIP4) simulations of the LIG produce a wide range of Arctic summer minimum sea ice area (SIA) results, with a 30 % to 96 % reduction from the pre-industrial (PI) period. Sea ice proxies are also currently neither abundant nor consistent enough to determine the most realistic state. Here we estimate LIG minimum SIA indirectly through the use of 21 proxy records for LIG summer surface air temperature (SSAT) and 11 CMIP6-PMIP4 models for the LIG. We use two approaches. First, we use two tests to determine how skilful models are at simulating reconstructed Δ SSAT from proxy records (where Δ refers to LIG-PI). This identifies a positive correlation between model skill and the magnitude of Δ SIA: the most reliable models simulate a larger sea ice reduction. Averaging the two most skilful models yields an average SIA of 1.3×10 6 km 2 for the LIG. This equates to a 4.5×10 6 km 2 or 79 % SIA reduction from the PI to the LIG. Second, across the 11 models, the averaged Δ SSAT at the 21 proxy locations and the pan-Arctic average Δ SSAT are inversely correlated with Δ SIA ( r = - 0.86 <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="49pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="9657313141bbfae45c345d44f0c9138f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-19-883-2023-ie00001.svg" width="49pt" height="10pt" src="cp-19-883-2023-ie00001.png"/></svg:svg> and −0.79 , respectively). In other words, the models show that a larger Arctic warming is associated with a greater sea ice reduction. Using the proxy-record-averaged Δ SSAT of 4.5±1.7 K and the relationship between Δ SSAT and Δ SIA suggests an estimated sea ice reduction of 4.2 ± 1.4 × 10 6 <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="72pt" ...
format Article in Journal/Newspaper
author L. C. Sime
R. Sivankutty
I. Vallet-Malmierca
A. M. de Boer
M. Sicard
author_facet L. C. Sime
R. Sivankutty
I. Vallet-Malmierca
A. M. de Boer
M. Sicard
author_sort L. C. Sime
title Summer surface air temperature proxies point to near-sea-ice-free conditions in the Arctic at 127 ka
title_short Summer surface air temperature proxies point to near-sea-ice-free conditions in the Arctic at 127 ka
title_full Summer surface air temperature proxies point to near-sea-ice-free conditions in the Arctic at 127 ka
title_fullStr Summer surface air temperature proxies point to near-sea-ice-free conditions in the Arctic at 127 ka
title_full_unstemmed Summer surface air temperature proxies point to near-sea-ice-free conditions in the Arctic at 127 ka
title_sort summer surface air temperature proxies point to near-sea-ice-free conditions in the arctic at 127 ka
publisher Copernicus Publications
publishDate 2023
url https://doi.org/10.5194/cp-19-883-2023
https://doaj.org/article/8572c7308d2e49b485f55b9faeb73f5a
geographic Arctic
geographic_facet Arctic
genre Arctic
Sea ice
genre_facet Arctic
Sea ice
op_source Climate of the Past, Vol 19, Pp 883-900 (2023)
op_relation https://cp.copernicus.org/articles/19/883/2023/cp-19-883-2023.pdf
https://doaj.org/toc/1814-9324
https://doaj.org/toc/1814-9332
doi:10.5194/cp-19-883-2023
1814-9324
1814-9332
https://doaj.org/article/8572c7308d2e49b485f55b9faeb73f5a
op_doi https://doi.org/10.5194/cp-19-883-2023
container_title Climate of the Past
container_volume 19
container_issue 4
container_start_page 883
op_container_end_page 900
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