Quantitative Analysis of Climate Change and Human Crises in History - Space-Time Integration in Geography and GIScience - page 249

of Revolution was not a general one. Even though there was an upsurge in grain
price, social disturbance, war, migration, and demographic crises did not happen.
This matches with the fact that the cooling during the time was mild.

14.3 Causal Mechanism for the Climate-Crisis Relationship

It has been shown in the previous section that various human crises became more
frequent in a period of deteriorating climate. The timing of the peaks of population
checks, population collapses, and socio-political chaos coincided, which implies
their interrelationship. In addition, the connection between climate change and
human crises was evidenced by quantitative and statistical findings. Although our
fundamental hypotheses (cf. Quantitative analysis of climate-crisis relationship) are
shown to be valid in explaining the climate-crisis relationship, the process that
translated climate change into various human crises is far too complicated to be
captured by them. To work out the complete set of causal linkages involved in the
translation of climate deterioration into human crisis, 26 we proceeded to examine
the climate-crisis causal mechanism in a period that contained both periods of
harmony and times of crisis (Zhang et al. 2011a ). Because the General Crisis of
the Seventeenth Century in Europe was marked by widespread economic distress,
social unrest, and population decline (Fischer 1996 ; Goldstone 1991 ;Parkerand
Smith 1978 ;Aston 1966 ), we systematically collected and tabulated all available
historical data about climate, agro-ecology, economy, society, human ecology,
and demography in Europe, AD 1500-1800. Sixteen variables 27 were identified
(Fig. 14.6 ) that facilitate our exploration of specific causal mechanisms between
climate change and human crisis. To elicit the real association between climate
change and the cyclic pattern of different variables, the variables with obvious long-
term trends (agricultural production index, grain price, real wages, body height, and
population size) were linearly detrended (Chu and Lee 1994 ; Galloway 1986 ).
Our study period covers both mild and cold phases of the Little Ice Age in the
Northern Hemisphere 28 (Fig. 14.6 a), while the fluctuations of all agro-ecological,

26 Given that we addressed whether climate change is a credible cause for large-scale societal crisis
from the macro-historic perspective, macro-historic and aggregate features are privileged over
micro-historic and individual ones; general trends are preferred to particular moments or events;
and broad distinctions or geographical uniformities take precedence over localized analyses.
27 Please refer to the SI Appendix, Materials and Methods I-XI of Zhang et al.'s ( 2011a ) study for
the specification and data source of each variable.
28 Based on the Northern Hemisphere (Fig. 14.6 a, red line, cf. footnote no. 12) and Euro-
pean (Fig. 14.6 a, black line, cf. footnote no. 24) temperature anomaly series, we divided our
study period into Mild Phase 1 (AD 1500-1559; average temperature D 0.43 ), Cold Phase

(AD 1560-1660; average temperature D 0.59 ), and Mild Phase 2 (AD 1661-1800; average

temperature 0.24 ). The Cold Phase coincided with the General Crisis of the Seventeenth

Century. In Mild Phase 2, there was brief cooling in AD 1700 and 1750.

D