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Abstract We explore the response of northeastern Pacific sea surface temperature (SST) to deglacial (16–7 ka) climate variability as recorded in‐based SST reconstructions spanning 65°N to 10°S. Included in the analysis is a new 23 kyr SST record from core NH8P from the northwest Mexican Margin. We isolate spatiotemporal patterns in regional SSTs with trend empirical orthogonal function (TEOF) analysis. The dominant TEOF mode reflects deglacial warming associated with rising. Tropical and subtropical SSTs correlated most strongly with this mode, suggesting that the thermodynamic response of the tropical eastern Pacific to greenhouse gas forcing was the dominant driver of regional SST change during deglaciation. The second TEOF mode reflects millennial‐scale variability and is most strongly expressed in subpolar SSTs. The synchronous timing between North Pacific and North Atlantic SST oscillations is evidence for the rapid transmission of millennial‐scale climate perturbations between the basins, likely through an atmospheric teleconnection. SSTs at NH8P have no correlation with either leading TEOF mode as there is minimal change in SST at this site after20 ka. A model simulation of the LGM indicates that glacial cooling was muted in much of the Eastern Pacific Warm Pool (EPWP), in which NH8P lies, due to reductions in latent heat flux. This suggests that the wind‐evaporation‐SST feedback was responsible for the attenuation of EPWP cooling. Overall, this study highlights the distinct latitudinal trends in the Pacific's response to deglaciation.
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Impacts of Paleoecology on the TEX 86 Sea Surface Temperature Proxy in the Pliocene‐Pleistocene Mediterranean Sea
Abstract The TEX86proxy, based on the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) from planktonic Thaumarchaeota, is widely used to reconstruct sea surface temperature (SST). Recent observations of species‐specific and regionally dependent TEX86‐SST relationships in cultures and the modern ocean raise the question of whether nonthermal factors may have impacted TEX86paleorecords. Here we evaluate the effects of ecological changes on TEX86using one Pliocene and two Pleistocene sapropels from the Mediterranean Sea. We find that TEX86‐derived SSTs deviate from‐derived SSTs before, during, and after each sapropel event.‐derived SSTs vary by less than 6 °C, while TEX86‐derived SSTs vary by up to 15 °C within a single record. Compound‐specific carbon isotope compositions indicate minimal confounding influence on TEX86from exogenous sources. Some of the variation can be accounted for by changes in nitrogen cycling intensity affecting thaumarchaeal iGDGT biosynthesis, as demonstrated by an inverse relationship between TEX86and δ15NTN. TEX86‐derived SSTs also consistently show warm anomalies in the Pleistocene, while the Pliocene samples exhibit both warmer and cooler relative offsets. These anomalies result from systematic differences between Plio‐Pleistocene iGDGT distributions and both modern Mediterranean and modern, globally distributed core top samples. Through characteristic GDGT distributions, we suggest the existence of three distinct endemic populations of Thaumarchaeota in the Pliocene, Pleistocene, and modern Mediterranean Sea, respectively. Importantly, these communities prevailed during both sapropel and oligotrophic conditions. Our results demonstrate that ecological and community‐specific effects must be considered when applying the TEX86proxy to paleorecords.
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- Award ID(s):
- 1702262
- PAR ID:
- 10462809
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Paleoceanography and Paleoclimatology
- Volume:
- 33
- Issue:
- 12
- ISSN:
- 2572-4517
- Page Range / eLocation ID:
- p. 1472-1489
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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