Little Ice Age Caused by Plague

From around 1500, Europe appears to have been gripped by a chill lasting some 300 years.

Pollen and leaf data support the idea that millions of trees sprang up on abandoned farmland, soaking up carbon dioxide from the atmosphere.

This would have had the effect of cooling the climate, a team from Utrecht University, Netherlands, says

The team found an increase in cereal pollen from 1200 onwards (reflecting agricultural expansion), followed by a sudden dive around 1347, linked to the agricultural crisis caused by the arrival of the Black Death, most probably a bacterial disease spread by rat fleas.

via BBC NEWS