Journal Article

The Pliocene Model Intercomparison Project Phase 2: Large-scale Climate Features and Climate Sensitivity

Contoux, Camille, Haywood, Alan M, Kamae, Youichi, Feng, Ran, Sohl, Linda E, Hill, Daniel J, Chandler, Mark A, Brady, Esther C, Dolan, Aisling M, Zhang, Zhongshi, Guo, Chuncheng, Li, Xiangyu, Foley, Kevin M, Chandan, Deepak, Lunt, Daniel H, Lohmann, Gerrit, Otto-Bliesner, Bette L, Chan, Wing-Le, Peltier, W Richard, Ramstein, Gilles, Stepanek, Christian, Hunter, Stephen J, Baatsen, Michiel L J, Tindall, Julia C, Li, Qiang, Abe-Ouchi, Ayako, Zhang, Qiong, Dowsett, Harry J, Tan, Ning, Heydt, Anna S von der, Nisancioglu, Kerim H

2020

Overview

The Pliocene epoch has great potential to improve our understanding of the long-term climatic and environmental consequences of an atmospheric CO2 concentration near ∼400 parts per million by volume. Here we present the large-scale features of Pliocene climate as simulated by a new ensemble of climate models of varying complexity and spatial resolution based on new reconstructions of boundary conditions (the Pliocene Model Intercomparison Project Phase 2; PlioMIP2). As a global annual average, modelled surface air temperatures increase by between 1.7 and 5.2 ∘C relative to the pre-industrial era with a multi-model mean value of 3.2 ∘C. Annual mean total precipitation rates increase by 7 % (range: 2 %–13 %). On average, surface air temperature (SAT) increases by 4.3 ∘C over land and 2.8 ∘C over the oceans. There is a clear pattern of polar amplification with warming polewards of 60∘ N and 60∘ S exceeding the global mean warming by a factor of 2.3. In the Atlantic and Pacific oceans, meridional temperature gradients are reduced, while tropical zonal gradients remain largely unchanged. There is a statistically significant relationship between a model's climate response associated with a doubling in CO2 (equilibrium climate sensitivity; ECS) and its simulated Pliocene surface temperature response. The mean ensemble Earth system response to a doubling of CO2 (including ice sheet feedbacks) is 67 % greater than ECS; this is larger than the increase of 47 % obtained from the PlioMIP1 ensemble. Proxy-derived estimates of Pliocene sea surface temperatures are used to assess model estimates of ECS and give an ECS range of 2.6–4.8 ∘C. This result is in general accord with the ECS range presented by previous Intergovernmental Panel on Climate Change (IPCC) Assessment Reports.

• Publisher: European Geosciences Union/Copernicus Publications,Copernicus GmbH,European Geosciences Union (EGU) [2005-....],Copernicus Publications
• Subject: Air temperature / Analysis / Annual / Annual precipitation / Atmospheric models / Boundary conditions / Carbon dioxide / Carbon dioxide atmospheric concentrations / Carbon dioxide concentration / Climate change / Climate models / Climate sensitivity / Climatology / Datasets / Earth Sciences / Experiments / Geology / Glaciation / Global temperature changes / Ice sheets / Intercomparison / Intergovernmental Panel on Climate Change / Meteorology And Climatology / Ocean circulation / Oceans / open climate campaign / Pliocene / Precipitation / Sciences of the Universe / Sea surface / Sea surface temperature / Sensitivity / Spatial discrimination / Spatial resolution / Statistical analysis / Surface temperature / Surface-air temperature relationships / Temperature / Temperature gradients / Topography / Tropical climate / Wind