For centuries, the unpredictable climate may be partly to blame for the fall of the Roman Empire. Detailed information on the European climate for 2500 years helped to identify the relationship between climate change and the rise and fall of several civilizations.
"Climate change has been a factor, which, along with the political failures and barbarian invasions, are important," — said the head of the project, Ulf Byuntgen (Ulf Buntgen), a Swiss specialist of the National Institute for Forest, Snow and Landscape Research.
Byuntgen used tree rings to reconstruct the history of European climate. Studying nearly 9000 specimens of oak, pine and larch Byuntgen and colleagues were able to recover both temperature and rainfall in Western Europe have changed in the last 2,500 years.
In the period between 250 and 550 years BC climate was changing at a tremendous rate, every decade that the climate was dry, then cool, then warm, then wet. "Such decadal changes seem to have had the greatest impact on civilization, because they caused damage to agriculture, as well as the periods are too short for people to be able to adapt to new conditions," — says Byuntgen.
Climate shocks, thus, coincided with political upheaval and waves of human migrations.
By the year 500 AD The Roman Empire fell. In other significant periods of relatively stable medieval society is characterized by a constant climate. But the period of the Black Death (pandemic plague) coincided with a humid climate, in which the disease is spreading rapidly.
"Relatively modest changes in the European climate in the past have had a significant impact on society," — said Michael Mann (Michael Mann) from Pennsylvania State University in University Park. Other studies have shown how war and climate are often closely related to each other. For example, periods of unusually cold weather in China during the last millennium associated with constant wars.
However, it is difficult to draw definite conclusions on the basis of research, such studies Byuntgena. "Modern society is not as dependent on the climate, as it once was, due to the development of technology and trade, which mitigate its effects," — said Halvard Buhaug (Halvard Buhaug) of the Peace Research Institute in Oslo, Norway. Currently the subject of heated debate is the relationship between the current wars in Africa and climate.
Byuntgen and his colleagues used 7284 sample oak from low-lying areas of France and Germany in order to fix the amount of spring precipitation, among other things, they used 1089 samples and 457 samples of pine larch
located in the Austrian Alps to determine summer temperatures. Other studies, including Mann, use similar methods to reconstruct a detailed reconstruction of global temperatures over the past 1,000 years.