Despite the climate fluctuation deniers activities, historical sources suggest some evidence of higher temperatures in the past, and fluctuations:
They indicate that the Romans had vineyards in Yorkshire around 200 AD.
A Welsh history I've read recently suggests temperatures about 2 degrees higher than now in about 450 AD, based on recorded agricultural/pastoral customs of the time.
Greenland was green when settled around 950 AD and the ice advanced during the period after 1100 AD.
The Thames had never been recorded as freezing over until shortly after this colder snap, but did then and several times subsequently, the tendency peaking in the mid 18th century.
In addition there is evidence of periods of lower and higher sea levels than now in the more distant past, which would imply climate fluctuation is not rare.
There is consistency between the historical sources.
One climate study I read recently suggested the world entered a warming phase about 12900 years ago, which was interrupted by a "mini ice age" between 1100 AD and the end of the 19th century, which peaked in the 18th century. This matches the historical data. The temporary cooling may be attributable to a disruption of the normal cycles by the planet passing through a field of cometary debris.
[I've posted links about this earlier in this thread.]
I am not saying this link is the "bible" as I haven't researched it myself, and only found the site today, but it is worth a read:
http://www.globalresearch.ca/index.php? ... &aid=10783