SUMMARY – THE HUMAN PAST (p.177-184 Chp 5 + Chp 11)
Chapter 5. Pages 177-184
Page 177. Climate Change and Faunal Extinction at the end of the Pleistocene
During the last Ice Age (c. 22,000-19,000BC) the temperatures had fallen and northern Europe
and North America were covered by thick ice sheets, resulting in arid climate. The sea levels
fell and this resulted in land bridges which linked Asia to Alaska. This also caused the
transformation of Southeast Asia into a peninsula called Sundaland.
Around 18,000 BC a slow and irregular warming process took off. During the
Bølling/Allerød interstadial (around 13,000 BC) the summer temperatures had almost
reached present day levels, but in Europe this trend was soon reversed with the Younger
Dryas phase (c. 10,800-9600BC) as the cold conditions returned.
Around 9600BC the warm conditions re-established fairly suddenly. At the end of the
Ice Age megafauna became extinct. It has been argued that both human predation and
environmental change must have been both partly responsible.
Page 179. The Early Holocene Environment
Coasts and Islands
The first 2000 years of the Holocene were a period of rapid change as the summer
temperatures once again reached present day levels and the rise in sea level led to the
drowning of low-lying areas. In the northern latitude the melting of the ice sheets even caused
the land areas to rebound (isostatic uplift). The sea level rise also created island. Most of the
land loss occurred during the late Pleistocene before 9600 BC. East Asia and North America
became divided by the flooding of the Bering Strait and Sundaland lost over half its land area
due to the rising sea levels. An area of low hills, Doggerland, became an island in the North
Sea until it was eventually flooded as well.
Forests and Deserts
As a response to the increased temperature and rainfall, the vegetation zones expanded. The
forest belt in Europe and North America with cold-climate trees was pushed northward and
replaced with oak, elm and beech. Furthermore, the open tundra shrank in size which may
also have caused the demise of megafauna as mentioned above. The changing combinations
of tree species have been found in the pollen cores and this even led to specific “pollen
zones”, concerning the different vegetation units.
The Inter-Tropical Convergence Zone moved north to pass over the Sahara and it became a
region of lakes within an extensive savanna grassland. During the 3rd millennium BC, however,
the climate patterns changed and the Sahara turned into a desert.
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