Speaker: Jiang Zhu, NCAR

Title: Constraining Model Climate Sensitivity through Simulation of Past Extreme Climates

Abstract: Many recent-generation climate models simulate a much higher (e.g., > 5 ℃) equilibrium climate sensitivity (ECS) than previous models and the decades-long consensus value (~3℃). Whether these high-ECS models are realistic has been hotly discussed in the climate science community. Here I demonstrate that simulation of the past extreme climates offers a unique opportunity to assess these high-ECS models, using the Community Earth System Model version 2 (CESM2) as an example. Further, I show that the paleoclimate observational data can be used to identify and improve the physical, numerical, and parametrical inconsistencies in CESM2. This study stresses the importance of paleoclimate in the assessment and development of climate models and in understanding the climate dynamics under warm conditions. Some implications on the equable climate problem, a classical problem in paleoclimatology, will also be briefly discussed.

Bio: Jiang Zhu is a Project Scientist at the National Center for Atmospheric Research. Jiang is fascinated by the wide range of climate conditions in Earth’s past such as the greenhouse and icehouse climates and their transitions. Jiang is a strong believer in the unique power of the past climate as a natural laboratory to investigate how the Earth system works. Jiang’s research focuses on the climate dynamics that drive large-scale changes in climate state, variability, and sensitivity through combining information from the geological record with Earth system modeling.