The Earth's climate cycles between long periods of ice age
in which the sea level is much lower than it is today, and in
which temperatures gradually rise, and much warmer climates.
Only 11,000 years ago the sea level was 400 feet lower than
it is today. Up until 150 years ago, the Earth was in cold
period that lasted three hundred years. Past Ice Ages have
nearly covered the Earth with the exception of a narrow
band at the Equator.
http://en.wikipedia.org/wiki/Ice_age

Ice Age cycles are cause by a number of factors. CO2,
the Earth's changes in axial tilt, precession, and the location
of large land masses near the poles. Mankind has little
effect on the climate.

The Little Ice was caused by a combination of reduced solar
activity, and increased volcanic activity. Both of these factors
are beyond human control.

http://en.wikipedia.org/wiki/Little_Ice_Age

Factors like undersea volcano's have proven dramatic effect
on things like melting the Ross Ice Shelf. Volcanic dust in
the atmosphere can cause a sudden shift downwards in
temperatures--not is a slow single degree per century rate,
but very fast drops in temperatures with widespread impact
on the climate.

One new theory has it that most human kind descended from
a small pool of about 1000 people 74,000 years back in time.
Analysis of mitochondrial DNA has revealed living humans are
strangely homogeneous genetically, presumably because they
originated recently from a small group or their ancestors
underwent a population bottleneck that wiped out most of
mankind.
http://www.unl.edu/rhames/neander/neander.htm

This is interesting because there was a major eruption of a
volcano 75000 years ago that would have had Apocalypse
consequences. Both geological and biological evidence
support each other.

http://volcano.und.nodak.edu/vwdocs/...esia/toba.html

It was projected that another ice age should already have
started. Many feel that industrialization forestalled the "Little
Ice Age". Perhaps it did. It could easily have been an
increase in solar flux. The Sun is far more significant than
mankind. However one theory is that methane produced
by farming, not the burning fossil fuels has delayed the onset
of another ice age.

The Earth will be either cooling or warming. Given a choice,
a slight warming trend is preferable to a fast cooling one.
However, there is a theory that slow warming eventually leads
to the slowdown of the Global Conveyor which could causes
fast cooling--another Ice Age.
http://www.commondreams.org/views04/0130-11.htm

So it seems that either we should have started a new Ice
Age a few hundred years ago, and we have been lucky
that global warming has postponed it, or perhaps that the
warming trend will lead to a shut down of the Global
Conveyor and this will lead to the fast onset of another Ice
Age.

The bottom line it that it will continue to get warmer, until
it gets much colder. We know that Ice Ages occur in just
a few short years. During the last ice age, ice covered the
area north of a line drawn between Cape May, New
Jersey and Seattle Washington. Here is a map showing
the typical coverage:
http://en.wikipedia.org/wiki/Image:P...th_ice_map.jpg

Look at this chart. The next Ice Age has started. Smart
people are moving south or west.
http://en.wikipedia.org/wiki/Image:V...core-petit.png