North American Tree Rings, Climatic Extremes, and Social Disasters - Dendroclimatology - page 297

10.1 Introduction
The impact of climate on society has been a controversial research focus from
the early days of dendrochronology. A.E. Douglass ( 1935 ) noted the coincidence
between tree-ring-dated climate extremes and prehistoric Anasazi activities on the
Colorado Plateau, including an increase in tree-ring-dated building activity during
wet years and decreased activity or complete village abandonment in dry years.
'The great drouth from 1276 to 1299 was the most severe of all those represented in
this 1200-year record and undoubtedly was connected with extensive disturbances
in the welfare of the Pueblo people' (Douglass 1935 , p. 49). 'Pueblo III, the golden
age of southwestern prehistory, took its early form in Chaco Canyon about 919 AD,
reached its local climax in the late eleventh century, and probably closed with the
great drouth of 1276-1299' (Douglass 1935 , p. 41). The first long tree-ring chronol-
ogy developed by Douglass for the American Southwest has been replicated by more
than 850 tree-ring chronologies now available for North America (Cook et al. 2004 ) ,
and Douglass' 'great drouth' of the late thirteenth century has been verified as one of
the most severe and protracted of the past 1000 years (Grissino-Mayer et al. 1997 ) .
However, the precise role of prolonged drought in the welfare of the Anasazi and
their ancient migrations remains an interesting and provocative research question.
There have been a number of more recent attempts to link paleoclimatic extremes
to famine, disease, and the collapse of human societies (Keys 1999 ; Diamond
2005 ) . These catastrophe scenarios have been fiercely controversial among anthro-
pologists, historians, and social theorists, and include viewpoints involving climate
determinism, Malthusian demographics, a famine-prone peasantry, and Marxist and
entitlement economic theory (Arnold 1988 ) . Elements of each viewpoint are evident
in many recent famines, and a loose consensus on the causes of modern hunger now
includes environmental hazards, food system breakdowns, and entitlement failure.
The impact of climatic hazards may have been greater among simple premodern
societies, but under some circumstances even modern, more complex societies can
suffer extreme climatic disruption. However, the impacts of climate and other geo-
physical hazards do tend to be greatest among impoverished segments of societies
(Ingram et al. 1981 ; Mutter 2005 ) , as has been demonstrated by the effects of the
southeastern Asia tsunami and hurricanes Katrina and Rita. It is anticipated that the
consequences of future anthropogenic climate change will continue to be greatest
among the poor (Houghton 1997 ) .
Two of the worst famines in world history illustrate the complex environmental,
socioeconomic, and political dimensions of these catastrophes. The so-called 'late
Victorian famines' of 1876-1879 across India, northern China, and Brazil—when
an estimated 16-31 million people perished—were initiated by a strong El Niño
event and extreme drought across the Indo-Pacific realm; the human tragedy, how-
ever, appears to have been aggravated by poverty, unrestrained market forces, and
incompetent government (Davis 2001 ) . Likewise, the catastrophic Chinese famines
of 1958-1961 that attended the 'Great Leap Forward'—when 16-30 million 'excess
deaths' occurred—began with drought but seem to have been magnified by Mao
Zedong's social experiments and failed centralization of Chinese agriculture (Davis