Climatic Change and the History of the Middle East
By: Arie S. Issar
From: American Scientist, July-August 1995
Exercises – J. Geffen
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1.
In some respects the effects of climate on human history are obvious and
undeniable. Who could deny that the repeated advance and retreat of the glaciers
during the ice ages of the Pleistocene had a profound effect on the geographic
distribution and livelihood of our ancestors? In another respect, however, the question
of how climate affects the course of human events on a less global scale is hardly a
trivial issue. Is it reasonable to look back at specific events in human history and reassess traditional interpretations, which often impute human actions, in the light of
evidence suggesting that accompanying climatic changes played a role? My own
answer to this question is yes, especially with respect to the history of the Middle
East.
2.
I have come to ask these questions in the course of my studies on the impact of
climatic change on the hydrological cycle (the global evaporation, condensation,
precipitation and flow of water). My research is at least partly motivated by the
current plight of the arid Middle East and the significance of water to the future
welfare of the region. It became apparent to me that climatic changes and the
hydrologic cycle must have had a profound effect on the history of the region as well.
Perhaps the past could provide a key to the future.
3.
As a model for understanding regional changes in other parts of the globe, the
history of the Middle East may provide a unique opportunity to assess the impact of
climatic change on the course of human events. For one thing, the climatic history of
the Middle East is known to have varied considerably during the past 10,000 years
(since the beginning of the agricultural revolution). This is probably related to the fact
that the region serves as an intermediate zone between the humid and arid belts of the
world. Locally, the region is also a transitional area between the moist Mediterranean
lands and the deserts of Egypt, Syria and Arabia. Second, the Middle East has the
benefit of a rich archeological and historical record. Where better to understand the
play between climate and human history?
History Reconsidered
4.
There are some notable events in the history of the Middle East that need to be
reassessed. The first of these concerns the Arab invasion in about 700 C.E. and the
coincident desertion of the Negev desert. The second addresses the instability and
abrupt collapse of large Mesopotamian civilizations in the span of a few centuries
around 2000 B.C.E. In both instances the traditional interpretations of history have
held that human activities had been the primary cause of the region’s decline. Some
recent studies suggest otherwise.
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5.
The force of the Arabs and the strength of the newly emerged religion of Islam
in the seventh century C.E. is undeniable. In the course of a century or so, the Arabic
peoples had spread throughout much of the Middle East as well as northern Africa
and Spain. At issue here is not the presence or the influence of the Arabs, but the view
that the Arab incursion was ultimately responsible for the destruction of the
agricultural economy and the invasion of sand dunes along the coastal plain of Israel
in the century that followed.
6.
Admittedly, in the late 1950s I was one of the proponents of this interpretation
in accordance with the prevailing paradigm that anthropogenic forces were behind
such changes to the landscape. In my studies of the region’s geology I had suggested
that the invading Arabs had destroyed the agriculture of the coastal plain, which until
then had controlled the invasion of sand dunes because of its vegetative cover.
7.
Such a scenario became suspect when it became apparent to me that a previous
massive invasion of sand dunes nearly 15,000 years earlier was the result of climatic
changes at the end of the last glacial period. My investigations of the fossil water
under Sinai and the Negev suggested that heavy rainstorms during the last glacial
period were full of dust. As the rain replenished the Nubian Sandstone aquifer beneath
Israel, the dust was deposited as the wind-blown loamy sediments, or loess layers, of
the Negev. At the end of the glacial period when the climate became warmer, the
deposition of the loess essentially ceased, and the sand dunes began their invasion into
the coastal plain.
8.
The invasion of the sand dunes can be partly explained by an increase in the
supply of sands from the Nile River. It seems that the end of the last glacial period
was associated not only with a warming trend in the Middle East but also with an
increase in the strength of the monsoon rainstorms over subtropical Africa. This, in
turn, increased the flow of water and sediments into the Nile. The coincident erosion
of the Nile delta caused by the rising sea level (itself a consequence of the melting
global ice and global warming) would have significantly increased the deposition of
sediments on the Mediterranean shores of Sinai and Israel. The result was a massive
movement of sand dunes onto the coastal plain.
9.
Such an explanation suggests that the relatively recent invasion of sand dunes in
800 C.E. may have another explanation. Perhaps the invading dunes that forced the
farmers out were caused by a climatic change rather than by an invasion by desert
peoples. Anthropogenic explanations for the desertification of the Negev are even
more dubious in the light of the enormous development and grandeur of the ancient
irrigation and agricultural systems of the Nabatean-Byzantine cities of the Negev,
which reached their peak in the fifth century. These cities and the agricultural terraces
along the river beds of the northern Negev were deserted at about the same time that
the young sand dunes started their advance into the coastal plain. This took place
more than a century after the Arab incursion.
Climatic Change and the History of the Middle East / 3
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10. Conventional explanations by archeologists and botanists maintain that the
richness of the cities and terraces was mainly the result of commerce. The desertion of
the farmers was attributed to the collapse of the administrative and commercial
systems that supported them. Yet this explanation does not appear to be consistent
with the actions of the inhabitants. If commerce was collapsing, why did the people of
the region develop every small valley for agriculture? Indeed, the agricultural
development nearly extended into an area where current rainfall lies below 80
millimeters per year, suggesting that they may have avoided only the most arid
regions. That conditions deteriorated significantly is evidenced by the observation that
the farmers deserted lands where contemporary levels of rainfall amount to nearly 250
millimeters per year. (At least 300 millimeters of rainfall per year is considered to be
necessary for sustainable agriculture.) Only after the farmers had essentially deserted
the Negev did the grazing animals of the newly arrived desert nomads intensify
desertification by removing the vegetative cover from the land.
11. At the same time, sea levels provide their own indications of relative
temperatures and rainfall. The level of the Mediterranean Sea, for example, rises and
falls with the world’s sea levels. Since a global rise in temperature should melt the
polar ice caps and raise the world’s oceans, any increases in the levels of the
Mediterranean Sea should indicate a warm period. A study in the mid-1980s by Avner
Raban and E. Galili of the University of Haifa shows that the Mediterranean Sea level
peaked between 400 and 800 C.E., supporting the notion that global temperatures did
rise at this time. In contrast, the level of the Dead Sea is not directly linked to the level
of the world’s oceans or global warmth. Rather, the levels of the Dead Sea are more
closely tied to the amount of rainfall in the region. Amos Frumkin of the Hebrew
University of Jerusalem has shown that the low levels of the Dead Sea in 800 C.E. are
consistent with a dry period at this time in history.
12. These indicators suggest that the transition between the Byzantine domination
of the Middle East and the Arab incursion around 700 C.E. was not the cause of the
desertification of the Negev and coastal plain of Israel. Rather, a drier and warmer
climate was probably the primary force behind the decline of rain-fed agriculture in
this part of the Middle East. Socioeconomic changes followed only after the land was
no longer arable. (Interestingly, the American geographer Ellsworth Huntington
arrived at the same conclusion at the beginning of this century. His studies of the
region were the basis of his theory of deterministic geography, which maintained that
changes in temperature and climate determine the ebb and flow of civilizations. The
theory was very popular until the 1930s, when it was totally abandoned by
geographers.)
13. Toward the end of the third millennium B.C.E., the ancient civilizations of the
Middle East had experienced their own set of difficulties. The southern
Mesopotamian empire of Sumer, situated primarily between the Tigris and the
Euphrates rivers, was struggling against Semitic invaders and internal conflicts. At
Climatic Change and the History of the Middle East / 4
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nearly the same time the northern Mesopotamian civilization of Subir was also
collapsing.
14. Historically, some of the internal conflicts of the Sumerians have been attributed
to a mishandling of the region’s irrigation-fed agriculture. The American
archeologists Thorkild Jacobsen and Robert Adams suggested that the Sumerians
were responsible for the salinization of their soils because many long irrigation
channels were used to excessively irrigate the land. In support of this notion Jacobsen
and Adams note that clay tablets in the Sumerian archives record that the ratio of
barley to wheat was constantly rising in the temple offerings and taxes. Since barley is
more tolerant than wheat to soil salinity, they proposed that Mesopotamian soils were
becoming progressively salinized. In effect, the Sumerians themselves were
responsible for the deterioration of the soil and their agriculturally based economy.
15. There is another explanation, however. Rather than being caused by the people,
the salinization may have resulted from a diminished flow of the Euphrates and the
Tigris rivers. As a result the inhabitants did not have enough water to irrigate and
flush the salts from their soils. A reduction in the flow of these rivers would be a
natural consequence of a warmer and drier climate. Is there any evidence for a
climatic change during this time period?
16. Some of the same methods that established the occurrence of a climatic change
in the latter half of the first millennium C.E. suggest that a significant change took
place toward the end of the third millennium B.C.E. Frumkin has noted that the level
of the Dead Sea dropped nearly100 meters in the span of a few centuries from 2400 to
2000 B.C.E., suggesting a dramatic increase in aridity. Raban and Galili’s study of the
levels of the historical Mediterranean Sea show an increase consistent with increasing
temperatures. A few hundred miles to the west, the Israeli archeologist Ruth Amiran
has observed that the Canaanite city of Arad in the northern Negev was deserted in
about 2600 B.C.E. the Israeli marine archeologist Avner Raban has observed that sand
invaded the coast and clogged the harbors of Canaan during the same period.
17. Other evidence for climatic change comes from a recent study of the collapse of
Subir in 2200 B.C.E. by H. Weiss of Yale University and his colleagues. The authors
note that the soil structure in the region indicates a reduction of soil water reserves
and increased evaporation. Their observations are consistent with a change in wind
patterns and decreased precipitation, perhaps the result of a volcanic eruption. Unable
to cultivate their cereal crops (the economic base of the civilization) because of the
desertification, the people abandoned Subir.
18. A revised interpretation of these events suggests that a warm, dry period
contributed to the collapse of adjacent empires in the Middle East around 2000
B.C.E., just as a warm dry period destroyed the agricultural economy of coastal Israel
in 800 C.E. The ancient peoples of these regions are not to blame for succumbing to
the harsh conditions.
Climatic Change and the History of the Middle East / 5
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The Past and the Future
19. My colleagues and I are currently taking a closer look at other periods in Middle
Eastern history to assess the fluctuations of the region’s climate. We have found, for
instance, that a cold spell that began in the third century B.C.E. resulted in the
greening of the deserts near the Mediterranean. One consequence appears to be that
the Nabatean peoples came down from the mountains of Transjordan to the Negev
desert and built a number of cities (including Avdat). We have also found evidence of
a relatively cold and humid period in the first century C.E. that may have
consequences for our interpretation of that period in history.
20. In some other work, I have attempted to relate the stories of the Bible and other
historical documents that describe environmental and socioeconomic changes to my
findings on the climatic changes of the past. In brief, my conclusion is that many
ancient stories do indeed echo severe climatic changes that had a strong impact on the
collective memory of the people in the region.
21. In general, I also suspect that there is a consistent relationship between climatic
change and its effects on the land and the people. In the Middle East, the warmest and
driest periods of the past 5,000 years are coincident with the largest invasions of
desert tribes into sown lands and the desertion of cities along the margins of the
desert. In contrast, cool and humid periods may be associated with the creation of
cities and agricultural economies.
22. A global rise in temperature results in a warmer and drier climate in the eastern
part of the Mediterranean (which belongs to the Westerlies climate system). This
relation is supported by general-circulation models, which take into consideration
such observations as the amount of solar radiation and the albedo qualities of the land,
to simulate climatic records of the past and to forecast large-scale changes in the
future. If the current warming trend is part of the Middle East’s climatic cycle, the
prospects for the region’s water resources are not hopeful. We may, in fact, be in a
warm recovery phase after the cold (Little Ice Age) period between 1550 and 1850
C.E. If true, the climatic consequences may surpass those forecast for the greenhouse
effect alone. Regions with a Mediterranean climate may suffer severe drought,
whereas those with a monsoonal climate may experience severe flooding. Lowlands
along sea coasts may be flooded due to the rise of the ocean levels.
23. All of these events may take place in the coming decades. Although little can be
done to stop the process, this pessimistic forecast can be at least partially mitigated by
human action. One possibility is the restoration of the vegetation that once covered
vast expanses of land in the semi-arid zones (along the borders of the desert belts) of
the world. Large vegetative regions would go far toward storing carbon dioxide, the
primary greenhouse gas. Such a tactic would obviously require a large international
effort that is dependent on the particular geographical conditions in each region. Much
more hydrological research must precede a green assault on desertified lands.
Climatic Change and the History of the Middle East / 6
Bibliography
Amiran, R. 1986. The Fall of the Early Bronze Age II city of Arad. Israel Exploration
Journal 36:74-76.
Frumkin, A., M. Magaritz, I. Carmi and I. Zak, 1991. The Holocene Climatic Record
of the Salt Caves of Mount Sedom, Israel. The Holocene 1(3):191-200.
Geyh, M.A. 1994. The Paleohydrology of the Eastern Mediterranean, in: Late
Quaternary Chronology and Paleoclimates of the Eastern Mediterranean, ed.
O. Bar-Yosef and R.S. Kra, pp. 131-145, Radiocarbon.
Huntington, E. 1911. Palestine and its Transformation. Boston: Houghton Mifflin.
Huntington, E. 1959. Mainsprings of Civilization. New York: New American Library.
Issar, A. 1985. Fossil water under the Sinai-Negev Peninsula. Scientific American
253(1):104-112.
Issar, A. 1990. Water Shall Flow from the Rock. Heidelberg: Springer Verlag.
Issar, A. 1994. The Impact of Climate Variations on Water Management Systems and
Related Socio-economic systems. A report of UNESCO/IHP Project IIc. (In
press.)
Jacobsen, T. 1960. The waters of Ur, Iraq. Science 222:174-185.
Jacobsen, T. 1957-1958. Salinity and Irrigation Agriculture in Antiquity, Diyala Basin
Archeological Project. Bibliotheca mesopotamia 14. Malibu: Udenda
Publication.
Jacobsen, T. and R.M. Adams. 1958. Salt and silt in ancient Mesopotamian
agriculture. Science 128:1251-1258.
Raban, A. and E. Galili. 1985. Recent maritime archaeological research in Israel – a
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Raban, A. 1987. Alternated River Courses During the Bronze Age Along the Israeli
Coastline. Colloque Internationeaux C.N.R.S. Deplacements de Lignes de
Rivages en Mediterranee. Ed. du C.N.R.S. Paris, pp. 173-189.
Stiller, M., A. Ehrlich, U. Pollingher, U. Baruch and A. Kaufman. 1984. The Late
Holocene Sediments of Lake Kinneret (Israel) – Multidisciplinary Study of a 5m
Core. Geological Survey of Israel, Ministry of Energy and Infrastructure,
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Climatic Change and the History of the Middle East / 7
Answer in your own words.
1.
2.
Answer the question below in English.
What does the title itself suggest?
Answer: _____________________________________________________________
Answer the question below in English.
What motivated the author – paragraph 2 – to conduct his research on climatic
change?
Answer: _____________________________________________________________
Answer the question below in Hebrew.
3.
What makes the Middle East – paragraph 3 – uniquely suitable for research on
the impact of climatic changes on the historical development of one or another
region?
Answer: _____________________________________________________________
4.
5.
Answer the question below in English.
To what end are the Arab invasion in about 700 C.E. and the sudden collapse of
large Mesopotamian civilizations of about 2000 B.C.E. reconsidered?
(Paragraphs 4-5)
Answer: _____________________________________________________________
Answer the question below in English.
What presumably erroneous thesis previously supported by the author himself –
paragraph 6 – is he now beginning to question?
Answer: _____________________________________________________________
Answer the question below in Hebrew.
6.
What – paragraph 7 – may have aroused the author’s scepticism about the
Arabs’ culpability in the desertification of the coastal areas?
Answer: _____________________________________________________________
Climatic Change and the History of the Middle East / 8
7.
8.
Answer the question below in English.
Provide the information – paragraphs 8-9 – that may suggest that the Arab
invaders should be exonerated on the issue at hand?
Answer: _____________________________________________________________
Answer the question below in English.
To what is the rise in Mediterranean sea level in the period between 400 and
800 C.E. – paragraph 11 – attributed?
Answer: _____________________________________________________________
Answer the question below in Hebrew.
9.
In what sense can the theories concerning the desertification of the Middle East
– paragraphs 1-18 – be considered guilty of confusing cause with effect?
Answer: _____________________________________________________________
10.
Answer the question below in English.
What are the author’s expectations for the coming decades – paragraphs 21-23?
Answer: _____________________________________________________________