The Azimuth Project
The Long Summer


The Long Summer (Basic Books, 2005) is a book by Brian Fagan which appears on our list of Recommended reading. It is a well-told story of the impacts of climate change on humans, starting at the tail end of the last glacial period, around 18,000 BC.


From Tables 1 and 2 of The Long Summer:

3,500 BCSub-Boreal?. Sahara, Egypt and Mesopotamia become much drier. Towns appear in Egypt. Cities develop in Mesopotamia.
4,500 BCDrought in American West, warm moist conditions in Europe. Cattle herded in the Sahara. Ertebolle culture in Scandinavia.
5,600 BCSea level rises, Mediterranean floods into the Euxine Lake?, forming the present-day Black Sea. Linearbandkeramik farmers move into Central Europe.
6,000 BCMini Ice Age. Laurentide ice sheet? collapses, AMOC slows. Farmers in the Balkans. First settlement in southern Mesopotamia.
8,000 BCFarming spreads rapidly in Southwestern Asia.
8,500 BC“Broad-spectrum hunter-gatherers” in Northern Europe.
9,500 BCPre-Boreal?. The AMOC resumes, with moister conditions and renewed warming. Farming spreads rapidly in southwestern Asia. Abu Hureyra II in Syria. Jericho
10,000 BCFarming begins in southeastern Asia; drought in southeastern Europe.
11,000 BCLake Agassiz spills, causing the AMOC to shut down, causing much colder temperatures in Europe: the Younger Dryas episode. Abu Hureyra I in Syria. Clovis culture in North America.
12,000 BCSpread of forests in Europe. Monte Verde / Meadowcroft. First settlement of the Americas. Cave painting at Niaux, France.
12,500 BCBeginning of the Bølling/Allerød. Rapid warming.
13,000 BCEnd of Heinrich event H1. First settlement in northeastern Siberia.
14,000 BCRapid sea level rise. The last Ice Age cultures in Europe.
15,000 BCClimatic amelioration in Eurasia.
16,000 BCLate Ice Age. Rapid retreat of ice sheets. Cro-Magnons in Europe.

Why “The Long Summer”?

The book focuses on the development of humans during the last 15 000 years. Brian Fagan stresses that this time period was both unusual warm and stable, compared to the preceeding 100 000 years. These extraordinary climatic conditions may be the reason why human civilization, as we know it today, could develop. Considering the more volatile and cold weather of the past, Fagan points out that we should expect that, sometime in the future, similar conditions will return. In this sense, the development of humans during the last 15,000 years happend during an unusual “long summer”.

Climate as a Key Influence in Human History

The key point of the book is of course that human life and culture have always been influenced by climate conditions and climate change, but that, due to the development of civilization, humanity as a whole has become increasingly vulnerable.

Settlement of America

According to archeology, the first settlements of humans on the American continents occurred around 15,000 BC, but there is some uncertainty of the exact time scale; Fagan mentions that there may have been first settlements already around 30,000 BC.

This is an example of a historic event that was only possible due to special climatic condition: around 15,000 BC there was a land bridge connecting Asia and North America, the Bering land bridge. Humans adapted to the environment of northern Asia were capable to cross this bridge. It is unlikely that they would have been able and motivated to cross the Pacific Ocean as it is today.

Increased Vulnerability

Fagan describes early human tribes living through the recent ice ages as opportunistic, flexible and mobile, moving and adapting their tool-kits to changing environmental conditions with ease. On the contrary, settlements consisting of towns and cities with a high concentration of people, relying on nearby agricultural supplies, cannot move, cannot adapt quickly enough, and therefore fail and crumble as soon as a changing climate renders their “survival toolkit” useless.

category: books