Roman Times: warmer
than now, vines grown for wine in SE England.
After
the 1st century AD there is evidence of a progressive rise in sea level.
AD
400 to 1000. The important invasions of western Europe by the Huns and
the Goths may have been generated by deteriorating climatic conditions
in central Asia. Radiocarbon dating and studies of the ancient Chinese
literature have disclosed that, when the glaciers of central Asia were
large, the meltwaters fed springs, rivers, and lakes on the edge of the
desert, and human communities flourished. When there was a warm phase,
the water supply failed and the deserts encroached.
Approximately
AD 1000-1250 the worldwide warm-up that culminated in the 10th century
and has been called the early Medieval Warm Period or the "Little Climatic
Optimum".
This
interval, extending roughly from AD 1250 to 1500, corresponds to the Paria
Emergence in the eustatic record and has
been
called one of the "little ice ages" by certain authors.
Little
Ice Age (1500-1850). Throughout most of what is commonly called the Little
Ice Age (1500-1850) the mean solar activity was quite low, but positive
fluctuations occurred around 1540-90 and 1770-1800.
The
year 1850 started a brief warming trend that persisted for 100 years. It
also approximates a critical turning point in climatic,
sea
level, glacial, and sedimentologic records.
The
Earth now is on a long-term cooling trend of the glacial-interglacial cycles
and is likely to continue so for several thousand
years,
but there are numerous modulating influences, meteorologic, geologic, and
man-made.
Geochronology: The Interpretation and Dating of the Geologic Record.
Copyright (c) 1996 Encyclopaedia Britannica, Inc.(extracts only).