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Reduced ENSO variability at the LGM revealed by an isotope‐enabled Earth system model
Author(s) -
Zhu Jiang,
Liu Zhengyu,
Brady Esther,
OttoBliesner Bette,
Zhang Jiaxu,
Noone David,
Tomas Robert,
Nusbaumer Jesse,
Wong Tony,
Jahn Alexandra,
Tabor Clay
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl073406
Subject(s) - thermocline , last glacial maximum , el niño southern oscillation , paleoclimatology , geology , holocene , climatology , foraminifera , oceanography , climate change , benthic zone
Studying the El Niño–Southern Oscillation (ENSO) in the past can help us better understand its dynamics and improve its future projections. However, both paleoclimate reconstructions and model simulations of ENSO strength at the Last Glacial Maximum (LGM; 21 ka B.P.) have led to contradicting results. Here we perform model simulations using the recently developed water isotope‐enabled Community Earth System Model (iCESM). For the first time, model‐simulated oxygen isotopes are directly compared with those from ENSO reconstructions using the individual foraminifera analysis (IFA). We find that the LGM ENSO is most likely weaker comparing with the preindustrial. The iCESM suggests that total variance of the IFA records may only reflect changes in the annual cycle instead of ENSO variability as previously assumed. Furthermore, the interpretation of subsurface IFA records can be substantially complicated by the habitat depth of thermocline‐dwelling foraminifera and their vertical migration with a temporally varying thermocline.