Reduced ENSO variability at the LGM revealed by an isotope‐enabled Earth system model
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- Department of Atmospheric and Oceanic Sciences and Center for Climatic Research University of Wisconsin‐Madison Madison Wisconsin USA
- Climate and Global Dynamics Division National Center for Atmospheric Research Boulder Colorado USA
- Department of Atmospheric and Oceanic Sciences and Center for Climatic Research University of Wisconsin‐Madison Madison Wisconsin USA, Now at Los Alamos National Laboratory Los Alamos New Mexico USA
- College of Earth, Ocean, and Atmospheric Sciences Oregon State University Corvallis Oregon USA
- NASA Goddard Institute for Space Studies New York New York USA
- Earth and Environmental Systems Institute Pennsylvania State University University Park Pennsylvania USA
- Department of Atmospheric and Oceanic Sciences and Institute of Arctic and Alpine Research University of Colorado Boulder Boulder Colorado USA
Abstract 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.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1390367
- Journal Information:
- Geophysical Research Letters, Journal Name: Geophysical Research Letters Vol. 44 Journal Issue: 13; ISSN 0094-8276
- Publisher:
- American Geophysical Union (AGU)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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