Climate changes on all time-scales. One of the most
important determinants of climate is variations in the
absorption of solar radiation by the planet.
Over billions of years the solar output has increased with
time, as has the evolution of the Earth`s atmosphere and
distribution of land and ocean which modifies the
efficiency at which the Earth can cool to space via
thermal/long wavelength radiation as well as impacting
absorption of sunlight.
Over tens and hundreds of thousands of years, changes in
the Earth`s orbit around the sun alter the amount of solar
radiation reaching different parts of the planet. These
cycles are predictable (they depend upon the gravitational
pulls of the sun, planets and the moon) and they are
widely believed to have caused glacial-interglacial cycles
in which global temperatures swing by up to 10oC.
However, crucial to these swings are feedbacks which
either amplify or dampen the radiative forcing from these
Milankovic cycles. For example, cooler temperatures lead