A Brief History of Climate, From Prehistory to The Imaginary Crisis of the 21st Century

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by Robert Girouard at wattsupwiththat.com

Climate history clearly shows that we’re living in a blessed time, and that past civilizations generally prospered during warm periods and declined during cold ones.

Since appearing in Africa a few hundred thousand years ago, Sapiens has had to contend with climatic changes of a magnitude and severity far beyond the benign warming we’ve experienced since the end of the Little Ice Age. These include at least two glacial-interglacial cycles, numerous major shifts in temperature and humidity, and cataclysmic eruptions such as that of the Toba volcano around 73,000 BP (yr before present), whose ashes darkened the sky for years.  Thanks to his intelligence, Sapiens not only overcame all these challenges posed by a turbulent and unpredictable nature, but also became increasingly resilient, less and less dependent on the climate.

A tumultuous prehistory

From 190,000 BP onwards, our distant African ancestors first faced the Riss glaciation, followed by the Würm glaciation. Default climate during these ices ages was cold, dry and dusty, and polar at higher latitudes.

The mega-droughts that affected much of tropical Africa between 135,000 BP and 75,000 BP made life very difficult, forcing Sapiens to take refuge in the caves along the South African coast (Blombos). The Great Lakes Tanganyika and Malawi, now several hundred meters deep, remained almost completely dry for several thousand years, on several occasions.

Sapiens experienced a brief interval of favorable climate during the Eemian interglacial, which began around 130,000 BP and lasted around 15,000 years. It was significantly warmer than today, as evidenced by the disappearance of the Arctic summer ice pack and Alpine glaciers, and the greening of the Sahara. During the heat peak, the oceans were on average 2°C warmer than at present, which implies much higher temperatures on land. Some archaic Sapiens took advantage of this exceptional climatic window to leave Africa.

Between 70,000 BP and 60,000 BP, thanks to improved and wetter conditions during the last ice age, populations migrated from the coasts of South Africa to East Africa, the starting point for new exits from Africa, this time by Sapiens sapiens. 

The first European Sapiens arrived around 45,000 BP (long after their Neanderthal cousins), and over the course of almost 30 millennia, the climate shifted back and forth, creating a veritable chaos. Trapped on the European peninsula, they survived some of the most brutal climatic changes of the last two million years, including a dozen sudden and pronounced warming events (Dansgaard-Oeschger events), with rises of 8°C to 10°C in just a few decades. In winter and during cold periods, the Cro-Magnon bands living in Western Europe took refuge in the valleys and caves of southern France and northern Spain. Even in these valleys, the average winter temperature was around 10°C lower than today.

During the Glacial Maximum, around 20,000 years ago, extreme cold and drought created horrific conditions almost everywhere. African lakes dried up again, deserts spread and human and animal populations collapsed.  Vegetation, deprived of an adequate supply of CO2, were crying for food. Dust levels in the atmosphere were 20 to 25 times higher than today. The temperature gradient between the poles and the tropics reached 60°C, 20°C higher than today, generating monster wind and dust storms.

A salutary global warming occurred 14,700 years ago.  This was the Bölling-Allerod, which lasted 2,000 years and was particularly beneficial for humans living in the Near East. In this warmer, wetter environment, where the Sahara was once again covered in vegetation, small villages sprang up and Natufian culture flourished.

This boom was suddenly interrupted by a terrible and sudden cooling, the Younger Dryas. For more than a millennium, the nascent civilization regressed. The Natufians once again became nomads, and Sapiens was forced to leave several regions that had become uninhabitable, including England, Belgium, the Netherlands and northern France. 

The Holocene and relative climate stabilization

Around 11,700 years ago, our Holocene interglacial began. Temperatures warmed within a generation, vegetation greened up, lakes and rivers swelled, animals flourished… and mankind began to prosper again.  And, as with the Bölling, it’s in the Near East, and more specifically in the Fertile Crescent, that civilization first bounced back.  Agriculture took root, livestock farming developed in parallel, the first cities (Jericho, Çatal Höyük, etc.) came into being, while cultural innovations such as the wheel, the plough and metallurgy multiplied.

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