The Little Ice Age was a period of cold temperatures that followed the Medieval Warm Period and had a 300-year duration (1550 to 1850). Several causes have been proposed for the Little Ice Age including decreases in solar radiation, volcanic activity and changes in ocean circulation, but there is no widespread consensus. The coldest and harshest stretch of the Little Ice Age was from 1560 to 1660, during which crop growing seasons grew shorter and the amount of land being farmed decreased. Researchers from the University of Hong Kong led by David Zhang reviewed data from Europe and other areas in the Northern Hemisphere between 1500 and 1800. They compared climate data with other information including population, growth rates, wars, agricultural production, famines, grain prices and wages. Health effects and food short- ages showed up almost immediately between 1560 and 1660. And an interesting trend developed – as the amount of farmland decreased, so too did the average height of Europeans. Average height declined by more than an inch and also closely followed the temperature decrease, as famine and malnourishment spread. Average height did not rebound until after 1650, when the temperatures increased. Zhang said “Temperature is not a direct cause of war and social disturbance. The direct cause of war and social disturbance is the grain price. That is why we say climate change is the ultimate cause.” Moving forward as our climate continues to change, Zhang warned “Developing countries will suffer more, because large populations in these countries rely on agricultural production.”

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Fall 2011 Newsletter