Global warming, or global cooling, in the last 10000 years? The Holocene temperature conundrum

Speaker: Zhengyu Liu, Professor of Climate Dynamics, Ohio State University

A seminar in the Bolin Centre Seminar Series, hosted by the Bolin Centre’s Research Area 5

Most previous temperature reconstruction of global annual temperature shows an early Holocene warming 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, leading to the Holocene temperature conundrum. Our critical re-examination of this apparent 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. A new analysis of tropical-subtropical mean-annual SST reconstruction produces a cooling trend, after using a method to filter the seasonal bias signal in the original SST reconstruction. The conundrum is likely resolved over the ocean.

This seminar was recorded on April 14, 2021