sharon sanders
Editor-in-Chief & President
Global climate change, war, and population
decline in recent human history
David D. Zhang*†, Peter Brecke‡, Harry F. Lee*, Yuan-Qing He§, and Jane Zhang¶
*Department of Geography, University of Hong Kong, Pokfulam Road, Hong Kong; ‡Sam Nunn School of International Affairs, Georgia Institute of
Technology, Atlanta, GA 30332-0610; §Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Science,
Lanzhou 730000, Gansu, China; and ¶Department of Anthropology, University College London, London WC1E 6BT, United Kingdom
Edited by Paul R. Ehrlich, Stanford University, Stanford, CA, and approved October 23, 2007 (received for review April 4, 2007)
Although scientists have warned of possible social perils resulting
from climate change, the impacts of long-term climate change on
social unrest and population collapse have not been quantitatively
investigated. In this study, high-resolution paleo-climatic data
have been used to explore at a macroscale the effects of climate
change on the outbreak of war and population decline in the
preindustrial era. We show that long-term fluctuations of war
frequency and population changes followed the cycles of temperature
change.
Further analyses show that cooling impeded agricultural
production, which brought about a series of serious social
problems, including price inflation, then successively war outbreak,
famine, and population decline successively.
The findings suggest that worldwide and synchronistic war–peace, population,
and price cycles in recent centuries have been driven mainly by long-term
climate change.
The findings also imply that social mechanisms that might mitigate the impact
of climate change were not significantly effective during the study period.
Climate change may thus have played a more important role and imposed
a wider ranging effect on human civilization than has so far been suggested.
Findings of this research may lend an additional dimension
to the classic concepts of Malthusianism and Darwinism.
http://www.pnas.org/cgi/reprint/0703073104v1
decline in recent human history
David D. Zhang*†, Peter Brecke‡, Harry F. Lee*, Yuan-Qing He§, and Jane Zhang¶
*Department of Geography, University of Hong Kong, Pokfulam Road, Hong Kong; ‡Sam Nunn School of International Affairs, Georgia Institute of
Technology, Atlanta, GA 30332-0610; §Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Science,
Lanzhou 730000, Gansu, China; and ¶Department of Anthropology, University College London, London WC1E 6BT, United Kingdom
Edited by Paul R. Ehrlich, Stanford University, Stanford, CA, and approved October 23, 2007 (received for review April 4, 2007)
Although scientists have warned of possible social perils resulting
from climate change, the impacts of long-term climate change on
social unrest and population collapse have not been quantitatively
investigated. In this study, high-resolution paleo-climatic data
have been used to explore at a macroscale the effects of climate
change on the outbreak of war and population decline in the
preindustrial era. We show that long-term fluctuations of war
frequency and population changes followed the cycles of temperature
change.
Further analyses show that cooling impeded agricultural
production, which brought about a series of serious social
problems, including price inflation, then successively war outbreak,
famine, and population decline successively.
The findings suggest that worldwide and synchronistic war–peace, population,
and price cycles in recent centuries have been driven mainly by long-term
climate change.
The findings also imply that social mechanisms that might mitigate the impact
of climate change were not significantly effective during the study period.
Climate change may thus have played a more important role and imposed
a wider ranging effect on human civilization than has so far been suggested.
Findings of this research may lend an additional dimension
to the classic concepts of Malthusianism and Darwinism.
http://www.pnas.org/cgi/reprint/0703073104v1