The Younger
Dryas were known as the
return to cold conditions
from 12,900-11,500 years ago. Paleoclimatic data shows this through
pollen
data that indicate that forests which had recently developed in Europe
during the aborted warming following the ice ages were suddenly
replaced
again by artic shrubs, herbs and grasses, and Greenland ice cores
indicate
a local cooling of about 6 degrees C during this event.
Following the Younger Dryas is the
present warm epoch,
known geologically as the Holocene Interglacial.
The
Holocene started suddenly around
11,500 years ago.
Greenland ice cores recorded a striking sudden cooling event about
8,200
years ago. This cooling event gave cool, dry conditions that lasted
about
200 years, before there was a rapid return to conditions warmer and
moister
than today. In addition, this cooling shows up in records from North
Africa
across southern Asia as a phase of arid conditions due to failure of
summer
monsoon rains. Furthermore, the cold and aridity also looks like it hit
northernmost South America, Eastern North America, and parts of North
Western
Europe.
1250-1850 AD= The Little Ice Ages
Following the Holocene there was a "Medieval Warm Period" which was followed by a longer span of considerably colder climates, often termed the "Little Ice Age" which was when the global mean temperature may have been 0.5 +/-1.0 degrees C colder than today.
Paleoclimatic
evidence shows that
Alpine glaciers moved
into lower elevations, rivers that rarely freeze today were often
completely
ice-covered in the winter time, and precipitation patterns also changed
in many regions.
Excerpt from:
http://www.atmos.washington.edu/1998Q4/211/project2/moana.htm
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