>>Luckily, we can look at the prospect of warming through the
>>historical record, not an uncertain computer model. The answer is
>>that we'd return to the finest weather in recorded history, the
>Medieval Climate Optimum (950-1300 A.D.).
>>All of the famous cathedrals and castles in Europe were built
>>during that period because people had time to spare from working
>>in the fields.
>just call it plain rubbish ! noone of the workers had spare time,
>there were no longlasting pattern in food production and hunger
>from the 12th to the 18th century. famines came and went
The climate optimum was a real phenomenon, of worldwide scope. I
believe (but am not sure) that the warming during that era dried things
out in the US Southwest to the extent that one or more Native American
To link that warming, however, to improved agriculture in Europe (a la
Avery...) is a stretch. Cereal yields did not appreciably decrease
after 1300. Such data are scarce (and not particularly reliable), but
those I have (from England, France, and Germany) show --- if anything
--- a continued *increase* in yields after the end of the MCO. Yield
ratios (seed harvested to seed planted) at the time were just plain
lousy. English wheat from 1200-1450 @ 3.8 +/- 0.1 (various 25-60 year
periods). Barley 3.8 +/- 0.3. Oats 2.5 +/- 0.3. France and Germany,
broadly similar. Italy, sketchy but apparently in the same range.
In today's teminology, these work out to 0.5 t/ha for wheat, 0.4 t/ha
for barley, and about 0.2 t/ha for oats (Wh = 8 bu/ac, Bar = 8
bu/ac, Oats = 5 bu/ac). Even compared to poor organic farmers today,
the yields are terrible. Those yields, however, were better than what
they had been before about 1000 AD. I believe the improved
agricultural situation related primarily to two *non*-climate factors
--- agricultural and military technology.
>From the time of Charlemagne onward, the adoption throughout Europe of
the heavy plow, the three-field rotation system, the nailed horseshoe,
improved harnesses, and the whippletree made a substantial difference
in the manor peasant's ability to work the land. By about 1200, the
horse (originally bred for military purposes) had largely replaced oxen
in the field. Horses work much faster than oxen.
Nor should we under-estimate the agricultural impact of the stirrup.
Stirrups enabled cavalry / knights to make lance charges without being
un-horsed. In effect it was the invention of the mediaeval "tank," and
it profoundly changed both tactics and strategic balance. In doing so
it opened up much better ag land for settlement. Prior to the 11th
century, most people lived in readily definsible areas --- hilltops,
heads of valleys, etc --- that generally precluded highly productive
soils. The stirrup opened up bottomlands and plains to relatively
secure (for the era) settlement and large areas of excellent land came
under cultivation for the first time.
Better land and better technology presumably increased yield ratios ---
and total harvest --- in the 11th century, but I haven't found the data
to back up that statement. Not surprisingly, the population increased
accordingly. In England, France, Germany, and Italy, populations
roughly tripled between 1000 and 1300. Many other social and economic
factors were (little doubt) involved, but there were certainly a *lot*
more people around to work on Cathedrals and many other projects, such
as continually enlarging the area enclosed by city walls.
By the early 14th century, population growth and urban concentration
had moved beyond the point of stability for that era. Conditions were
ripe for "correction," by famine or plague. Although there had been
localised food shortages, such as in 1317, the famine or plague
question was definitively answered in 1348 by the Black Death. The
point is, however, that all this was going on largely independent of
the Mediaeval Climate Optimum.
PS --- if you want to look at *real* global warming, consider the
Eocene (about 45 million years ago). The climate of Ellesmere Island
(Canada) at 80 degrees North latitude was roughly equivalent to that of
Memphis. There are vast fossilized cypress forests on Ellesmere, and
geo-magnetic studies have established that the island was very close to
its present position at the time of those cypress forests. If we are to
be concerned about warming, it should be for selfish human reasons ike
coastal flooding, increased storminess, droughts, and the like ---
Earth will make out just fine, but we might not.
To Unsubscribe: Email email@example.com with the command
"unsubscribe sanet-mg". If you receive the digest format, use the command
To Subscribe to Digest: Email firstname.lastname@example.org with the command
All messages to sanet-mg are archived at: