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Title: Investigating the Direct Meltwater Effect in Terrestrial Oxygen-Isotope Paleoclimate Records Using an Isotope-Enabled Earth System Model

Abstract

Variations in terrestrial oxygen-isotope reconstructions from ice cores and speleothems have been primarily attributed to climatic changes of surface air temperature, precipitation amount, or atmospheric circulation. In this work, we demonstrate with the fully coupled isotope-enabled Community Earth System Model an additional process contributing to the oxygen-isotope variations during glacial meltwater events. This process, termed “the direct meltwater effect,” involves propagating large amounts of isotopically depleted meltwater throughout the hydrological cycle and is independent of climatic changes. We find that the direct meltwater effect can make up 15–35% of the δ 18O signals in precipitation over Greenland and eastern Brazil for large freshwater forcings (0.25–0.50 sverdrup (10 6 m 3/s)). Model simulations further demonstrate that the direct meltwater effect increases with the magnitude and duration of the freshwater forcing and is sensitive to both the location and shape of the meltwater. These new modeling results have important implications for past climate interpretations of δ 18O.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [5]; ORCiD logo [6]; ORCiD logo [7]; ORCiD logo [8]; ORCiD logo [9]; ORCiD logo [10]
  1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Atmospheric and Oceanic Sciences and Center for Climatic Research; Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Earth and Environmental Sciences
  2. The Ohio State Univ., Columbus, OH (United States). Atmospheric Science Program and Dept. of Geography
  3. National Center for Atmospheric Research, Boulder, CO (United States). Climate and Global Dynamics Lab.
  4. Univ. of Wisconsin, Madison, WI (United States). Dept. of Geoscience
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  6. Nanyang Technological Univ. (Singapore). Earth Observatory of Singapore and Asian School of the Environment
  7. NASA Goddard Inst. for Space Studies (GISS), New York, NY (United States)
  8. Univ. of Colorado, Boulder, CO (United States). Dept. of Computer Science
  9. Univ. of Colorado, Boulder, CO (United States). Dept. of Atmospheric and Oceanic Sciences and Inst. of Arctic and Alpine Research
  10. Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23). Climate and Environmental Sciences Division; National Science Foundation (NSF); National Center for Atmospheric Research, Boulder, CO (United States)
OSTI Identifier:
1441337
Alternate Identifier(s):
OSTI ID: 1415072
Report Number(s):
LA-UR-18-20282
Journal ID: ISSN 0094-8276
Grant/Contract Number:  
AC52-06NA25396; AGS‐1401778/1401803/1401802; NSFC41630527; 1566432
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 44; Journal Issue: 24; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; direct meltwater effect; oxygen-isotope records; ice cores; speleothem records; meltwater

Citation Formats

Zhu, Jiang, Liu, Zhengyu, Brady, Esther C., Otto-Bliesner, Bette L., Marcott, Shaun A., Zhang, Jiaxu, Wang, Xianfeng, Nusbaumer, Jesse, Wong, Tony E., Jahn, Alexandra, and Noone, David. Investigating the Direct Meltwater Effect in Terrestrial Oxygen-Isotope Paleoclimate Records Using an Isotope-Enabled Earth System Model. United States: N. p., 2017. Web. doi:10.1002/2017GL076253.
Zhu, Jiang, Liu, Zhengyu, Brady, Esther C., Otto-Bliesner, Bette L., Marcott, Shaun A., Zhang, Jiaxu, Wang, Xianfeng, Nusbaumer, Jesse, Wong, Tony E., Jahn, Alexandra, & Noone, David. Investigating the Direct Meltwater Effect in Terrestrial Oxygen-Isotope Paleoclimate Records Using an Isotope-Enabled Earth System Model. United States. doi:10.1002/2017GL076253.
Zhu, Jiang, Liu, Zhengyu, Brady, Esther C., Otto-Bliesner, Bette L., Marcott, Shaun A., Zhang, Jiaxu, Wang, Xianfeng, Nusbaumer, Jesse, Wong, Tony E., Jahn, Alexandra, and Noone, David. Thu . "Investigating the Direct Meltwater Effect in Terrestrial Oxygen-Isotope Paleoclimate Records Using an Isotope-Enabled Earth System Model". United States. doi:10.1002/2017GL076253.
@article{osti_1441337,
title = {Investigating the Direct Meltwater Effect in Terrestrial Oxygen-Isotope Paleoclimate Records Using an Isotope-Enabled Earth System Model},
author = {Zhu, Jiang and Liu, Zhengyu and Brady, Esther C. and Otto-Bliesner, Bette L. and Marcott, Shaun A. and Zhang, Jiaxu and Wang, Xianfeng and Nusbaumer, Jesse and Wong, Tony E. and Jahn, Alexandra and Noone, David},
abstractNote = {Variations in terrestrial oxygen-isotope reconstructions from ice cores and speleothems have been primarily attributed to climatic changes of surface air temperature, precipitation amount, or atmospheric circulation. In this work, we demonstrate with the fully coupled isotope-enabled Community Earth System Model an additional process contributing to the oxygen-isotope variations during glacial meltwater events. This process, termed “the direct meltwater effect,” involves propagating large amounts of isotopically depleted meltwater throughout the hydrological cycle and is independent of climatic changes. We find that the direct meltwater effect can make up 15–35% of the δ18O signals in precipitation over Greenland and eastern Brazil for large freshwater forcings (0.25–0.50 sverdrup (106 m3/s)). Model simulations further demonstrate that the direct meltwater effect increases with the magnitude and duration of the freshwater forcing and is sensitive to both the location and shape of the meltwater. These new modeling results have important implications for past climate interpretations of δ18O.},
doi = {10.1002/2017GL076253},
journal = {Geophysical Research Letters},
number = 24,
volume = 44,
place = {United States},
year = {Thu Dec 28 00:00:00 EST 2017},
month = {Thu Dec 28 00:00:00 EST 2017}
}

Journal Article:
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