A0262
Title: A state space representation of a two-component energy balance model
Authors: Mikkel Bennedsen - Aarhus University (Denmark)
Eric Hillebrand - Aarhus University and CREATES (Denmark)
Jingying Zhou Lykke - Aarhus University (Denmark) [presenting]
Abstract: A state-space representation (EBM-SS model) of the two-component energy balance model (EBM) is proposed. The EBM-SS model incorporates three extensions to the two-component EBM. First, we include ocean heat content (OHC) as a measurement of the temperature in the deep ocean layer. Second, we decompose the latent state of radiative forcing into a natural component and an anthropogenic component. Lastly, we use multiple GMST (Global Mean Surface Temperature) anomaly data sources from separate research groups as measurements for the latent states in the two-component EBM. We estimate the EBM-SS model using observations at the global level during 1955 - 2020 by maximum likelihood. We show in empirical estimation and in simulations that using multiple data sources for the latent process reduces parameter estimation uncertainty. When fitting eight observational GMST anomaly series, the physical parameter estimates are comparable to those obtained by using datasets from the Coupled Model Intercomparison Project 5 (CMIP 5) in other literature. We find that using this set of estimates, the GMST projection results under four Representative Concentration Pathway (RCP) scenarios considerably agree with the outputs from the climate emulator Model for the Assessment of Greenhouse Gas Induced Climate Change (MAGICC) 7.5 and CMIP 5 models. We show that utilizing a simple climate model and historical records alone can produce meaningful GMST projections.
