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Climate change and human civilization

Looking at the past to understand what’s happening today. In this way you could summarize how Archaeology and Anthropology contribute to our comprehension of Climate Change and its impact on our societies.

Grand Unified Timeline of Human History

Mexico City


Analyzing ancient pollen grains from Larnaca Salt Lake in Cyprus,

scientists concluded that a massive drought caused the collapse of Late Bronze Age civilizations about 3,200 years ago.

“The end of the human race will be that it will eventually die of civilization.” ~ Ralph Waldo Emerson

Climate Chaos: The Monkey Wrench that Unravels Everything

“We are approaching the planet’s limitations. So when I see the media barrage about buying more stuff, it’s almost like a science fiction movie where .. we are undermining the very ecological systems which allow life to continue, but no one’s allowed to talk about it.”  Annie Leonard, founder of the Story of Stuff project, a Berkeley-based effort to curb mass consumption.

Mainstream economists universally reject the concept of limiting growth:

As Larry Summers, a former adviser to President Obama, once put it, “The idea that we should put limits on growth because of some natural limit is a profound error, and one that, were it ever to prove influential, would have staggering social costs.”

We’re in a Sci-Fi movie, not allowed to talk about how we’re destroying the ecologial systems we depend on

Archeologist Brian Fagan, author of the book The Great Warming Climate Change and The Rise and Fall of Civilizations, explains how ancient Climate Change affected the Earth in the past and how some civilizations (such are the Pueblo Indian from Chaco Canyon, New Mexico, at the beginning of the 11th century, or the Egyptian civilization in 2180 BC) were able to adapt to the changed climate while other civilizations perished under the effect of a silent elephant walking across centuries.

Watch the video interview with Brian Fagan at the International Workshop The Social Dimension of Adaptation to Climate Change in Venice:

Studying Ancient Climate Change: The Great Warming

The lessons of the past give us clues to what we should look to for the future. If you combine the long-term view with the view of today, you get a unique picture of how humans have adapted to ancient Climate Change

The Silent Elephant in the Room

Who (or what) is the silent elephant walking across centuries? A metaphor invented to describe dangers and threats from the past to the present of Climate Change

Adaptation to Ancient Climate Change: Two Successful Stories

Twelve hundreds years ago the Pueblo Indians survived the fifty-years drought; more than twenty centuries Before Christ the Egyptian civilization found the way to face the impacts of climate change.

Plan B


Jared Diamond

Collapse: How Societies Choose to Fail or Succeed


In 2001, archaeologists digging in Peru revealed a shocking discovery: massive man-made structures, hundreds of feet in diameter, built with stone and dirt. They fo­und dozens of these mounds in the arid valleys of Peru’s Norte Chico region, running from the Andes Mountains to the west coast.

These certainly aren’t the first mounds discovered in Peru, but there’s something special about them. They may represent a shift in the most basic understanding of the origins of civilization in the Americas.

They look like flat-topped pyramids, up to 85 feet (26 meters) tall. Compared to the pyramids of the Mayan empire i­n South America or, later, the Incan empire in Peru — structures that were hundreds of feet tall — that’s not so impressive. Except that these mounds in Norte Chico predate any large structures attributed to either the Incas or the Mayans. (They’re even older than the Egyptian pyramids, for that matter.) It seems that these Peruvian mound builders were the first complex civilization in the Americas.

­­The recently discovered mounds, found to be about 5,000 years old, predate the early Mayans by perhaps a thousand years. But perhaps even more surprising is the location of the mounds within Peru. Civilizations tend to develop around resource availability. People are naturally drawn to abundance in water and food sources.

But the Norte Chico region of Peru is totally dead. The archaeologists were digging in a place that seems incapable of supporting life. The land is dry as a bone, and there are very few water sources and hardly any green things as far as the eye can see.

Why would an advanced civilization spring up in such a desolate place? How could the mound builders have survived under such circumstances, let alone thrived to the point of introducing a new way of life in the Ameri­cas?

The answer, according to the group of archaeologists who discovered the mounds, could be something very familiar to present day civilizations: climate change. It starts with the discovery of seashells in a nearly waterless stretch of Peru.


The Anthropocene is an informal geologic chronological term that serves to mark the evidence and extent of human activities that have had a significant global impact on the Earth’s ecosystems.

The term was coined recently by ecologist Eugene F. Stoermer and has been widely popularized by the Nobel Prize-winning atmospheric chemist, Paul Crutzen, who regards the influence of human behavior on the Earth’s atmosphere in recent centuries as so significant as to constitute a new geological epoch for its lithosphere.

In 2008 a proposal was presented to the Stratigraphy Commission of the Geological Society of London to make the Anthropocene a formal unit of geological epoch divisions. A large majority of that Stratigraphy Commission decided the proposal had merit and should therefore be examined further.

Steps are being taken by independent working groups of scientists from various geological societies to determine whether the Anthropocene will be formally accepted into the Geological Time Scale.

To date, the term has not been adopted as part of the official nomenclature of the geological field of study, but many scientists are now using the term and the Geological Society of America entitled its 2011 annual meeting: Archean to Anthropocene: The past is the key to the future.

The Anthropocene has no precise start date, but based on atmospheric evidence may be considered to start with the Industrial Revolution (late eighteenth century). Other scientists link the new term to earlier events, such as the rise of agriculture and the Neolithic Revolution (around 12,000 years BP).

Evidence of relative human impact such as the growing human influence on land use, ecosystems, biodiversity, and species extinction is controversial; some scientists believe the human impact has significantly changed (or halted) the growth of biodiversity.

Those arguing for earlier dates posit that the proposed Anthropocene may have begun as early as 14,000 to 15,000 years before present, based on lithospheric evidence; this has led other scientists to suggest that “the onset of the Anthropocene should be extended back many thousand years”; this would be closely synchronous with the current term, Holocene.

Climate change

Modern climate change could have a devastating effect on the habitability of large parts of the planet. Through the effects of higher temperatures, quickly rising seas, agricultural failure, drought, increased warfare, rapid climate fluctuations, and shifting weather patterns, modern civilization could be forced through some drastic transformations, or to complete disintegration.

Humanity has weathered many a climate change, from the ice age of 80,000 years ago to the droughts of the late 19th century that helped kill between 30 and 50 million people around the world via famine. But such shifts have transformed or eliminated specific human societies, including the ancient Sumerians and the Ming Dynasty in China, as highlighted in a review paper published January 30 in Proceedings of the National Academy of Sciences.

It wasn’t until the end of the Ice Age around 10,000 B.C., that many things began to change which affected the people and the land. When the ice melted, it caused flooding to cover the lowland areas and new plants started to emerge. People started to farm animals and crops. The changing climate created an environment which encouraged people to settle in one place.

The development of agriculture helped people to settle in villages and create communities. When they had enough crops in storage, some of the people developed specialized trades or crafts. This formed an economy since the goods could be traded. This led to the first civilizations.

Between 12.8 and 11.6 thousand years ago the latter stage of the postglaciation warming was interrupted by a major cooling phase, the “Younger Dryas” — probably caused by the sudden massive release of melt-water from Canada’s thawing ice sheets into the Atlantic, disrupting that ocean’s heat circulation system. Over several centuries the temperature dropped by approximately 4 to 5 °C.

At that time early human settlements were forming in several regions with good year-round food sources, including the Natufians in today’s northern Syria and the settlements along the Nile Valley. Archaeological research has identified several dozen Nile settlements that preceded the Younger Dryas. After that climatic shock, however, only a few survived. Regional skeletal remains evince an unusually high proportion of violent deaths, many accompanied by remnants of weapons.

Meanwhile, in the Natufian region, as food supplies dwindled, most settlements disbanded. The several that managed to survive may have been progenitors of successful settled agriculture once warming resumed, culminating in the relatively stable Holocene climate.

A thousand-year chill led people in the Near East to take up the cultivation of plant foods; a catastrophic flood drove settlers to inhabit Europe; the drying of the Sahara forced its inhabitants to live along the banks of the Nile; and increased rainfall in East Africa provoked the bubonic plague.

The Sumerians

While the rest of the world is worried about melting glaciers in Greenland and the shrinking of the polar icecaps, resulting in the flooding of New York and other low-lying areas, Matt Konfirst, a geologist at the Byrd Polar Research Centre has been concerning himself with the climate change which happened a few years ago. 4,200 years ago, to be precise.

Exactly what caused the drought is uncertain. The Middle East in general has become drier over the years and the deforestation caused by human activity has almost certainly played a part in this, but whether deforestation was as great and as widespread back in the Third Millennium BC is probably doubtful. On the other hand, the usual culprits – sunspot activity or an outburst of volcanic activity – is not likely as those factors would not last for two centuries.

A 200-year-long drought 4,200 years ago may have killed off the ancient Sumerian language, one geologist says. Because no written accounts explicitly mention drought as the reason for the Sumerian demise, the conclusions rely on indirect clues. But several pieces of archaeological and geological evidence tie the gradual decline of the Sumerian civilization to a drought.

The secrets of El Niño, one of the most mysterious and destructive weather systems, could be unlocked by hundreds of thousands of ancient clay tablets now feared lost or damaged in the chaos of Iraq. Researchers believe the tablets, written using a cuneiform text, one of the earliest types of writing, form the world’s oldest records of climate change and could give vital clues to understanding El Niño and global warming.

Southern Mesopotamia (Sumeria), encompassing the lower Tigris and Euphrates river flood-plains, was apparently the first region to develop regional-scale agriculture and a polity of multiple connected villages and towns as trading centers.

The regions climate reflects a complex, seasonally varying set of weather systems: the “Atlantic” circulation (west winds, warmth, and seasonal rain) driven by the North Atlantic Oscillation (NAO); interdecadal latitudinal fluctuations of the arid subtropical “ridge”; the West Asian monsoon system; and periodic cold dry air from the north (the Siberian High).

During the first, longer phase of the warmer Holocene Climatic Optimum (6000–3800 BCE, the positive “Atlantic” weather pattern of the NAO predominated. This, plus river irrigation, facilitated the spread of agriculture. Then, as Sumeria’s climatic configuration began to change in the 4th millennium BCE, increasing food insecurity and hunger emerged.

Ecologically, the agricultural productivity of the Sumerian lands was being compromised as a result of rising salinity. Soil salinity in this region had been long recognized as a major problem. Poorly drained irrigated soils, in an arid climate with high levels of evaporation, led to the buildup of dissolved salts in the soil, eventually reducing agricultural yields severely.

During the Akkadian and Ur III phases, there was a shift from the cultivation of wheat to the more salt-tolerant barley. However, the crisis deepened, starvation spread, the authority of rulers dwindled, and local farming communities raided one another. Clay tablets and carvings on stone steles attest to growing misery, conflict, starvation, and several epidemic outbreaks.

Extended irrigation and substitution of (more salt-tolerant) barley for wheat may have provided some relief, but this was insufficient, and during the period from 2100 BC to 1700 BC, it is estimated that the population in this area declined by nearly three fifths.

This period is generally taken to coincide with a major shift in population from southern Mesopotamia toward the north. This greatly weakened the balance of power within the region, weakening the areas where Sumerian was spoken, and comparatively strengthening those where Akkadian was the major language.

The underfed weakened state Sumeria was conquered by the warrior-king Sargon, ruler of the upstream Akkadian empire (northern Mesopotamia). Henceforth Sumerian would remain only a literary and liturgical language, similar to the position occupied by Latin in medieval Europe.

The drying conditions subsequently extended north and, after brief regional domination, the Akkadian empire collapsed around 2200 BCE, largely undone by drought, malnutrition, and starvation. Following an Elamite invasion and sack of Ur during the rule of Ibbi-Sin (c. 1940 BC), Sumer came under Amorites rule (taken to introduce the Middle Bronze Age).

The independent Amorite states of the 20th to 18th centuries are summarized as the “Dynasty of Isin” in the Sumerian king list, ending with the rise of Babylonia under Hammurabi c. 1700 BC.

The Late Bronze Age Collapse

Archaeologists have debated for decades over what caused the once-flourishing civilizations along the eastern Mediterranean coast to collapse about 1200 BC. Many scholars have cited warfare, political unrest and natural disaster as factors. But a new study supports the theory that climate change was largely responsible.

Analyzing ancient pollen grains from Cyprus, researchers concluded that a massive drought hit the region about 3,200 years ago. Ancient writings have described crop failures, famines and invasions about the same time, suggesting that the drying trend triggered a chain of events that led to widespread societal collapse of these Late Bronze Age civilizations.

Ancient civilizations flourished in regions of the Eastern Mediterranean such as Greece, Syria and neighboring areas, but suffered severe crises that led to their collapse during the late Bronze Age. Here, researchers studied pollen grains derived from sediments of an ancient lake in the region to uncover a history of environmental changes that likely drove this crisis.

Shifts in carbon isotopes in the Eastern Mediterranean and in local plant species suggest that this lake was once a flourishing harbor that gradually dried into a land-locked salt lake. As a result, crop failures led to famines, repeated invasions by migrants from neighboring regions and eventually, the political and economic collapse of the Eastern Mediterranean civilizations at the end of the late Bronze Age.

Combining this data with archeological evidence from cuneiform tablets and correspondence between kings, the researchers suggest that the late Bronze Age crisis was a complex, single event comprised of climate change-induced drought, famines, sea-borne invasions and political struggles, rather than a series of unrelated events. They conclude that this event underlines the sensitivity of these agriculture-based societies to climate, and demystifies the crisis that led to their end.

The Mayas

There are two proposed methods of Classic Maya collapse: environmental and non-environmental. The environmental approach uses paleoclimatic evidence to show that movements in the intertropical convergence zone likely caused severe, extended droughts during a few time periods at the end of the archaeological record for the classic Maya.

The non-environmental approach suggests that the collapse could be due to increasing class tensions associated with the building of monumental architecture and the corresponding decline of agriculture, increased disease, and increased internal warfare.

Modern research has found that the classic Maya civilization collapsed at the end of a long period of wet weather, as it gave way to drought. As the local climate changed, the civilization and its products disintegrated, leading to widespread famine, endemic warfare, and the collapse of cities.

From the tenth to the fifteenth century the earth experienced a rise in surface temperature that changed climate worldwide—a preview of today’s global warming. In some areas, including western Europe, longer summers brought bountiful harvests and population growth that led to cultural flowering. In the Arctic, Inuit and Norse sailors made cultural connections across thousands of miles as they traded precious iron goods. Polynesian sailors, riding new wind patterns, were able to settle the remotest islands on earth.

But in many parts of the world, the warm centuries brought drought and famine. Elaborate societies in western and central America collapsed, and the vast building complexes of Chaco Canyon and the Mayan Yucatán were left empty. The history of the Great Warming of a half millennium ago suggests that we may yet be underestimating the power of climate change to disrupt our lives today — and our vulnerability to drought, writes Fagan, is the “silent elephant in the room.”

The change in the Central American climate during the collapse of the Maya civilization was due to a massive, undulating, natural weather pattern. This weather pattern alternately brought extreme moisture, which fostered the growth of the Maya civilization, and periods of dry weather and drought on a centuries-long scale.

During the wet periods agriculture expanded and allowed the population and urban centers to grow. This process reinforced the centralized power that the kings of these centers possessed. The kings are known to have claimed credit for the things that the region was dependent on but had no control of, such as the rains and the weather.

The supposed mechanism of this influence over the elements were the ritualized public blood sacrifices for which the Maya are well known. Because the power of the kings over their subjects was largely dependent on a favorable climate for agriculture, their rule could be greatly influenced by changes in the climate. It’s very easy to argue that modern civilization is no different — without large-scale agriculture, it’s hard to imagine any semblance of it persisting for long.

When the rains finally did stop, around the year 660, the kings’ power is known to have been largely diminished, and correlated very closely with a large increase in warfare over the now scarce resources.

The political collapse of the Maya kings came around the year 900, when prolonged drought undermined their authority. But Maya populations remained for another century or so, when a severe drought lasting from the years 1000 to 1100 forced Maya to leave what used to be their biggest centers of population.

The Maya also had their own hand in the collapse of their agricultural system. Their farming (like modern farming) led to soil erosion and nutrient depletion. They combated this by intensifying their farming. Using more land and more irrigation, and that in turn caused greater ero