PP005-08
Glacial Heinrich events mute water isotope records at Greenland due to sea ice
Monday, 7 December 2020: 05:58
Virtual
Chengfei He1, Zhengyu Liu2, Bette L Otto-Bliesner3, Esther C Brady4, Chenyu Zhu5, Robert A Tomas6, Peter U Clark7, Jiang Zhu8, Alexandra Jahn9, Sifan Gu10, Jiaxu Zhang11, Jesse M Nusbaumer3, David Noone12 and Hai Cheng13, (1)Ohio State University Main Campus, Columbus, OH, United States, (2)The Ohio State University, Columbus, OH, United States, (3)National Center for Atmospheric Research, Climate and Global Dynamics Laboratory, Boulder, CO, United States, (4)National Center for Atmospheric Research, Boulder, Boulder, CO, United States, (5)Peking University, Department of Atmospheric and Oceanic Sciences, School of Physics, Beijing, China, (6)NCAR, Boulder, CO, United States, (7)Oregon State University, Corvallis, OR, United States, (8)National Center for Atmospheric Research, Boulder, CO, United States, (9)University of Colorado Boulder, Atmospheric and Oceanic Sciences and Institute of Arctic and Alpine Research (INSTAAR), Boulder, CO, United States, (10)University of Wisconsin Madison, Madison, WI, United States, (11)Los Alamos National Laboratory, Los Alamos, NM, United States, (12)University of Auckland, Department of Physics, Auckland, New Zealand, (13)University of Minnesota, Department of Earth Sciences, Minneapolis, MN, United States
Abstract:
The climate change during the last deglaciation, characterized by several abrupt fluctuations, is well preserved in stable water isotope (δ18O) proxies over the globe. The transition from the last Glacial Maximum to Heinrich 1, however, seems absent in δ18O at Greenland, while highly coherent δ18O enrichment appears in Asian speleothems. Here we performed a transient deglacial simulation in a water isotope enabled fully coupled climate model to decipher the evolution of δ18O at Greenland. It is shown that the water isotope response at Greenland is directly controlled by the sea ice extent due to freshwater forcing, while the Asian δ18O is a response of the sea surface temperature associated with freshwater and orbital forcings. Our study reveals that muted Heinrich 1 event results from the cancellation between enrichment and depletion effects induced by the north Atlantic sea ice that may lead to a potentially undetectable δ18O-temperature temporal slope under glacial background.
