CHINA: November 23, 2007
Reporting by Tan Ee Lyn; Editing by Bill Tarrant
HONG KONG - Global warming is one of the most significant threats facing humankind, researchers warned, as they unveiled a study showing how climate changes in the past led to famine, wars and population declines.
The world's growing population may be unable to adequately adapt to ecological changes brought about by the expected rise in global temperatures, scientists in China, Hong Kong, the United States and Britain wrote in the journal Proceedings of the National Academy of Sciences.
Trawling through history and working out correlative patterns, the team found that temperature declines were followed by wars, famines and population reductions.
The researchers examined the time period between 1400 and 1900, or the Little Ice Age, which recorded the lowest average global temperatures around 1450, 1650 and 1820, each separated by slight warming intervals.
"When such ecological situations occur, people tend to move to another place. Such mass movement leads to war, like in the 13th century, when the Mongolians suffered a drought and they invaded China," David Zhang, geography professor at the University of Hong Kong, said in an interview on Thursday.
"Or the Manchurians who moved into central China in 17th century because conditions in the northeast were terrible during the cooling period," he said.
"Epidemics may not be directly linked to temperature (change), but it is a consequence of migration, which creates chances for disease to spread."
HALF THE WORLD AT RISK
Although the study cited only periods of temperature decline to social disruptions, the researchers said the same prediction could be made of global warming.
A report last week said climate change will put half the world's countries at risk of conflict or serious political instability.
International Alert, a London-based conflict resolution group, identified 46 countries – home to 2.7 billion people – where it said the effects of climate change would create a high risk of violent conflict. It identified another 56 states where there was a risk of political instability.