Abstract
Climate energy balance models (EBMs) – simple energy-balance-based
models of climate change – are widely used. The simplest “linear” EBM
is deficient in capturing the behavior of complex climate models, so a
“two-layer” model with an additional degree of complexity, i.e. two
vertical layers, is typically used. Other additional degrees of
complexity are equally plausible as well, however, and different
approaches to add a degree complexity have not been compared
quantitatively. Here we compare four types of EBMs - two-layer,
order-two (temperature-dependent feedback), two-region (in space), and
two-timescale (fast and slow climate responses) - specifically, their
ability to capture historical temperature change and simulated
temperature changes in abrupt (4x) and gradual (1%-ramp) forcing
scenarios. The two-region model outperforms the others. The two-region
model’s best-fit parameters to historical temperatures are also more
physically plausible than the next-best-fitting model, the two-layer
model. We therefore conclude that the two-region model is the preferred
climate EBM.