Formulating an Energy Balance Model - Climate Change: Identification and Projections - page 50

present in GCMs, insofar as they model a linearizable climatic process as a
first approximation.

( G is specific to each type of
EBM. It depends on its structure; the definition of finite macro-elements
adopted: continents, oceans, hemispheres, cryosphere, atmospheric or ocean
layers, and so on. It combines, in a complex way, thermal input and
coefficients of exchange between these compartments. Insofar as EBMs, like
GCMs, appear to be representative of the same climatic reality, all simulated
responses will necessarily have the same appearance.

However, the form of the transmittance )

As a result, the following curve (Figure 4.2) is taken from Stowasser
(2006). It comes from the simulation of a GCM 4 driven by a step of solar
irradiance of 5%, which corresponds to a net variation of

− 2

Wu . The
final temperature is 8°C, (possibly more, if the text is to be believed). The
coefficient of climate sensitivity to net irradiance

= 12

2

would S = Δ T / u

2 2

− 2

therefore be equal to

WC , a value which complies with the
IPCC's estimated values (see section 5.5 below).

0 666 ° /

Figure 4.2. Climatic response simulated by GCM (---) and
rational approximation ( -- )

4 Coupled General Circulation Model version 3 of the Canadian Centre for Climate
Modelling and Analysis (CCCma)