level of solar insolation (on decadal to centennial
time-scales) are far too small to produce the
changes that are observed in the world's mean
temperature. However, there is considerable
anecdotal evidence (e.g. the Little-Ice-Age and
the Maunder Minimum) to suggest that whenever
the level of Sun's magnetic activity decreases,
there is an associated decrease in the world's
There has been a general agreement that there
must be some supplementary mechanism that
is synchronized with the changes in the level
of solar activity which serves to effectively
"amplify" the small changes caused by the
weak variations in solar insolation. Some of
the proposed mechanisms have included:
a) Svensmark's Cosmic-Ray Cloud Model
b) The effects of variations in UV upon energy
absorption in the Ozone Layer.
c) Thermal heating of the Stratosphere by the
But what if there another mechanism that
was responsible for this amplification?
The Astro-Climate Model.
This particular model claims that the "amplification" is
actually caused by the effects of long-term variations
in the lunar tides upon the Earth’s LOD, atmospheric
tides, and oceanic upwelling (via tidal dissipation).
The model further claims that it is the tidally induced
changes in these parameters that effect the Earth's
climate through their long-term influence upon the
ENSO and AMO.
According to this model, it is the periodicities in the
planetary gravitational and tidal forces that are
determining the long-term periodicities that are
observed in the level of solar activity as well as the
long-term variations that are seen in the strength
of the lunar tides (as experienced on the Earth).
This produces a natural synchronization between
the changes in the Earth's climate that are caused
by the Sun and those that are produced by the Moon.
The model proposes that it is this synchronization
between these two drivers of long-term climate
change that is the cause of the amplification.