Formulating an Energy Balance Model - Climate Change: Identification and Projections - page 48

of the two dominates. There must be a wide margin of stability due to
primary radiation increasing with temperature, since the planet has not been
definitively transformed into a glacier or a boiler under the influence of
volcanism or variations of CO 2 that it has experienced throughout the Earth's
history.

The terrestrial albedo also contributes in several fundamentally different
ways. Its average “nominal” value is 30%. It may vary from this for a
number of reasons: 1. due to the effect of deforestation which is an
independent anthropogenic cause. The result is not a reaction, but a radiative
forcing (and the changing use of land should also be added to the list of
causal inputs outlined); 2. due to the effects of temperature variation T G
itself, including the lower increase for snow-covered tundra and Canadian
plains. Hence this time it is a destabilizing reaction, giving a negative
contribution in the coefficient . The albedo brings solar irradiance into

play, but the reaction above is nonetheless related to the variation in global
temperature. The variation in irradiance only has a second-order effect,
which by definition is not taken into account in the linear approximation of
the total TOA flow.

λ

G

These subtleties are not easy to grasp. To summarize: there is no specific
feedback for a given input of radiative forcing, whether for CO 2 , irradiance
or volcanism; the temperature T G remains the intermediary from which the
reaction is taken, whatever the primary cause of its variation. Confusion
often arises - and not only among non-specialists. As a result, many people,
starting from an increase in CO 2 , methodically follow step by step the effects
on temperature T G , the increase in partial pressure of H 2 O which results from
this, and so on (while usually relying on destabilizing reactions). However,
in any case, the starting point is irrelevant: once a variation in T G is obtained,
the rest of the causality chain remains identical, whether the source is CO 2,
variations in volcanic activity, or random disturbances of atmospheric or
ocean currents. Supposing that the climatic machine does not have a wide
margin of stability, the impact of CO 2 is not necessarily more destabilizing
than any other.

The terms of change themselves, especially for climate disruption,
damage the concept behind the model itself: they imply that some