TY - JOUR
T1 - Seasonal and Latitudinal Response of New Zealand Sea Surface Temperature to Warming Climate Since the Last Glaciation
T2 - Comparing Alkenones to Mg/Ca Foraminiferal Reconstructions
AU - Sikes, Elisabeth L.
AU - Schiraldi, Benedetto
AU - Williams, Amanda
N1 - Funding Information: ELS thanks a long stream of dedicated undergraduates who assisted in the lab to extract sediments and catalog data, especially Kristine Babyak. Special thanks go to Katelyn Mineo, who produced the first working alkenone SST record for the Bay of Plenty. We thank Julie Kalansky for her assistance with Mg/Ca analyses and quality control. Our thanks also go to Eli Hunter who created all the figures and managed the data with cheer and style. Two anonymous reviewers provided comments that helped improve the manuscript. Funding for this project came from NSF OCE‐0823487 and 0823549‐03. Data are archived with NOAA NCDC at https://www.ncdc.noaa.gov/paleo/study/28090. Funding Information: ELS thanks a long stream of dedicated undergraduates who assisted in the lab to extract sediments and catalog data, especially Kristine Babyak. Special thanks go to Katelyn Mineo, who produced the first working alkenone SST record for the Bay of Plenty. We thank Julie Kalansky for her assistance with Mg/Ca analyses and quality control. Our thanks also go to Eli Hunter who created all the figures and managed the data with cheer and style. Two anonymous reviewers provided comments that helped improve the manuscript. Funding for this project came from NSF OCE-0823487 and 0823549-03. Data are archived with NOAA NCDC at https://www.ncdc.noaa.gov/paleo/study/28090. Publisher Copyright: © 2019. American Geophysical Union. All Rights Reserved.
PY - 2019/11/1
Y1 - 2019/11/1
N2 - Dual proxies were used to estimate paleo sea surface temperatures (SST) for the Bay of Plenty, north of New Zealand. (Formula presented.) and Mg/Ca in the planktonic foraminifera Globogerina bulloides reconstruct SST for the growth seasons for the organisms they are based upon. (Formula presented.) SST (summer) were consistently ~ 3.5 °C warmer than Mg/Ca (spring), suggesting that Bay of Plenty SST during the last glacial maximum (LGM) was 17.3 °C in summer and 13.8 °C in spring. Combining these results with published data based on the same proxies from other sites around New Zealand shows cooling of 3–4 °C in both seasons at all sites in the LGM relative to the Holocene. This indicates that overall, glacial surface water cooling was similar in subtropical and subpolar waters in both spring and summer. This contrasts with published foraminiferal assemblage reconstructions suggesting greater subantarctic cooling during the LGM. Deglacial warming across the region was characterized by changes in both seasonal and latitudinal temperature differences. Warming began in subtropical waters at ~21 ka, ~ 1.5 ka earlier than in subantarctic water. In the Bay of Plenty, the seasons maintained a consistent offset, while in Hawke Bay, springs stayed cold while summers warmed until after the Antarctic Cold Reversal. In contrast, subantarctic spring SST warmed rapidly, causing temperature differences to decrease between the Chatham Rise (subantarctic) and subtropical sites, possibly caused by shifting westerly winds. The use of multiple proxies enhances our understanding by adding a seasonal component to the glacial story of climate change in the southwest Pacific Ocean.
AB - Dual proxies were used to estimate paleo sea surface temperatures (SST) for the Bay of Plenty, north of New Zealand. (Formula presented.) and Mg/Ca in the planktonic foraminifera Globogerina bulloides reconstruct SST for the growth seasons for the organisms they are based upon. (Formula presented.) SST (summer) were consistently ~ 3.5 °C warmer than Mg/Ca (spring), suggesting that Bay of Plenty SST during the last glacial maximum (LGM) was 17.3 °C in summer and 13.8 °C in spring. Combining these results with published data based on the same proxies from other sites around New Zealand shows cooling of 3–4 °C in both seasons at all sites in the LGM relative to the Holocene. This indicates that overall, glacial surface water cooling was similar in subtropical and subpolar waters in both spring and summer. This contrasts with published foraminiferal assemblage reconstructions suggesting greater subantarctic cooling during the LGM. Deglacial warming across the region was characterized by changes in both seasonal and latitudinal temperature differences. Warming began in subtropical waters at ~21 ka, ~ 1.5 ka earlier than in subantarctic water. In the Bay of Plenty, the seasons maintained a consistent offset, while in Hawke Bay, springs stayed cold while summers warmed until after the Antarctic Cold Reversal. In contrast, subantarctic spring SST warmed rapidly, causing temperature differences to decrease between the Chatham Rise (subantarctic) and subtropical sites, possibly caused by shifting westerly winds. The use of multiple proxies enhances our understanding by adding a seasonal component to the glacial story of climate change in the southwest Pacific Ocean.
KW - Sea surface temperature
KW - Uk37- alkenones
KW - foraminiferal Mg/Ca
KW - last deglaciation
KW - last glacial maximum
KW - southern hemisphere climate
UR - http://www.scopus.com/inward/record.url?scp=85075765920&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85075765920&partnerID=8YFLogxK
U2 - https://doi.org/10.1029/2019PA003649
DO - https://doi.org/10.1029/2019PA003649
M3 - Article
VL - 34
SP - 1816
EP - 1832
JO - Paleoceanography and Paleoclimatology
JF - Paleoceanography and Paleoclimatology
SN - 2572-4517
IS - 11
ER -