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Reduced ENSO Variability at the LGM Revealed by an Isotope-Enabled Earth System ModelStudying the El Nino 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.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Zhu, Jiang (Wisconsin-Madison Univ. Madison, WI, United States)
Liu, Zhengyu (Wisconsin-Madison Univ. Madison, WI, United States)
Brady, Esther (National Center for Atmospheric Research Boulder, CO, United States)
Otto-Bliesner, Bette (National Center for Atmospheric Research Boulder, CO, United States)
Zhang, Jiaxu (Wisconsin-Madison Univ. Madison, WI, United States)
Noone, David (Oregon State Univ. Corvallis, OR, United States)
Tomas, Robert (National Center for Atmospheric Research Boulder, CO, United States)
Nusbaumer, Jesse (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Wong, Tony (Pennsylvania State Univ. University Park, PA, United States)
Jahn, Alexandra (Colorado Univ. Boulder, CO, United States)
Tabor, Clay (National Center for Atmospheric Research Boulder, CO, United States)
Date Acquired
February 5, 2018
Publication Date
July 12, 2017
Publication Information
Publication: Geophysical Research Letters
Volume: 44
Issue: 13
ISSN: 0094-8276
Subject Category
Meteorology and Climatology
Report/Patent Number
Funding Number(s)
Distribution Limits
El Niño–Southern Oscillation;isotope-enabled simulation;direct model-data com