Climate variations

If we have many geological markers we can draw a eustatic graph which traces the different sea levels over the millennia. For instance, 220,000 years ago the sea was 3 meters below its current level and about 140,000 years ago it was as much as 140 meters below its level nowadays. Right after that, during the Tirrenian period about 125,000 years ago it rose suddenly to 7 meters above today’s level. That was a very warm period, much warmer than it is today and with a much higher concentration of carbon dioxide. Obviously, if the sea level was 7 meters above what it is today, many of the current coast areas, such as Venice, did not exist. At a much more recent time, about 22,000 years ago, there was the last glacial acme, which is the coldest moment of the last glacial era which had lowered the sea level by approximately 120 meters. At this time half of the Adriatic was dry land, Corsica and Sardinia were joined together, Elba was part of the peninsula, and Sicily was joined both to Italy and to Africa.
Thanks to these dry lands, many African animals were able to migrate and settle in Italy (i.e. rhinoceros and elephants). Once the islands became separated from Italy, these species adjusted to the new environment, spawning new characteristics such as dwarfism. In fact, fossil remains were found in Sicily of a dwarf elephant that was no more than 1 meter tall. It was much smaller than its African relatives because on the island there were no predators that it would have needed to protect itself from but there was also little food available. With this great a decrease in sea levels, man found new fertile lands and hunting territories. After the glacial acme, the sea level started rising again until the present day. Therefore, at the end of the Glacial Era, a new warm phase began and the ices have melted making the sea rise very quickly (about 10 meters in 100 years). In fact we find both historical and religious references to this period which became known as the Deluge. The plains that were inhabited by man were flooded by the sea which forced man to move several times in a lifetime, specially in the areas surrounding the Black Sea which are rather flat. About 10,000 years ago the sea was 50 meters below today’s level, then there was a global warming trend so the sea level rose suddenly about 5,000 years ago. This phase peaked approximately between 7,500 and 4,600 years ago, when Earth reached its highest temperatures in the past 10,000 years. About 6,000 years ago the Sahara had a very humid climate and was covered with grass lands that were inhabited by highly civilized populations.

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