Join host John Green to learn about the Little Ice Age, a period of global cooling that occurred from the 13th to the 19th centuries. This cooling was likely caused by a number of factors, including unusual solar activity and volcanic eruptions. The Little Ice Age greatly impacted human social orders, especially during the 17th century. When the climate changed, and weather became unpredictable, the world changed profoundly. Poor harvests led to hunger, which led to even less productivity, which even resulted in violent upheaval in many regions.