Global Warming or Global Cooling in the Holocene?
Zhengyu Liu1, Jiang Zhu2, Yair Rosenthal3, Xu Zhang4, Bette L Otto-Bliesner2, Axel Timmermann5, Robin S Smith6, Gerrit Lohmann7, Weipeng Zheng8 and Oliver Timm9, (1)The Ohio State University, Department of Geography, Columbus, United States, (2)NSF National Center for Atmospheric Research, Boulder, United States, (3)Rutgers University, Department of Marine and Coastal Sciences, New Brunswick, United States, (4)Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), Paleo-climate Dynamics, 27570 Bremerhaven, Germany, (5)IPRC-SOEST, Honolulu, HI, United States, (6)University of Reading, Reading, United Kingdom, (7)Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany, (8)Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China, (9)University at Albany, State University of New York, Department of Atmospheric and Environmental Sciences, Albany, NY, United States
Abstract:
A recent temperature reconstruction of global annual temperature shows early Holocene warmth followed by a cooling trend through the middle to late Holocene. This global cooling is puzzling because it is opposite to the expected and simulated global warming trend due to the retreating ice sheets and rising atmospheric greenhouse gases (GHGs). Our critical re-examination of this contradiction between the reconstructed cooling and the simulated warming points to potentially significant biases in both the seasonality of the proxy reconstruction and the climate sensitivity of current climate models.
