Quantitative Analysis of Climate Change and Human Crises in History - Space-Time Integration in Geography and GIScience - page 238

Table 14.2 Pearson's correlation coefficients between temperature anomaly and wars in different
geographic regions in the world in AD 1400-1900. All data have been smoothed by 40-year
Butterworth low-pass filter prior to statistical analysis
Va r i a b l e s
War Temp anomaly Correlation coefficient (r)

Worl dwi de a 0.279*** e Global

Worl dwi de b Global 0.285***

Worl dwi de c Global 0.329***

N. Hemisphere c N. Hemisphere 0.390***

S. Hemisphere c S. Hemisphere 0.408***

Asia c N. Hemisphere 0.235***

Arid areas in the N. Hemisphere c

N. Hemisphere 0.473***

Europe c N. Hemisphere 0.458***

Western Europe c N. Hemisphere 0.329***

Eastern Europe c

N. Hemisphere 0.548***

North America c

N. Hemisphere 0.112*

South America c S. Hemisphere 0.188***

West & Central Africa c

S. Hemisphere 0.404***

East & South Africa c

S. Hemisphere 0.444***

China d 0.264***

*Significant at 0.05 level (2-tailed) ( P < 0.05); ***Significant at 0.001 level (2-tailed) ( P < 0.001)
a Data source: Wright ( 1942 )
b Data source: Luard ( 1986 )
c Data source: Brecke ( 1999 )
d Data source: Editorial Committee of Chinese Military History ( 1985 )
e n

N. Hemisphere

D

419 (i.e., AD 1482-1900)

or subtropical environment, where a fall in temperature would have a smaller effect
than elsewhere on agricultural production and would not reduce food resources to
the same extent because there is more alternative food. The American continents
had a very low population density and a large amount of fertile land during this
period, and their values are therefore either insignificant or of very low significance.
Europe and Africa have either large cold areas or desert areas relatively vulnerable
to cooling, and we find that warfare there is highly correlated with the temperature
anomalies. At the global scale, the temperature anomaly is simply an arithmetic

Fig. 14.2 Climate change, wars, and population growth in different geographic regions in the
world in AD 1400-1900. ( a ) Temperature anomaly ( ı C) in the Northern Hemisphere that is
smoothed by 40-year Butterworth low-pass filter. ( b ) Number of wars in the Northern Hemisphere
( bright green ), Asia ( pink ), Europe ( turquoise ), and the arid areas in the Northern Hemisphere
( orange ). ( c ) Number of wars worldwide as recorded by Wright ( 1942 )( turquoise ), Luard ( 1986 )
( orange ), and Brecke ( 1999 ). ( d ) Population growth rate (in 20-year units) in Europe ( turquoise ),
Asia ( pink ), and the Northern Hemisphere ( blue ), together with the Northern Hemisphere fatality
index ( bright green , in 50-year units). Cold phases are shaded as gray stripes . All war time series
are in decadal units. The bright green curves correspond to the right y-axis (Color figure online)