The Little Ice Age was a period of cooling that occurred between 1350-1850 AD. It began after a period of warming from 900-1300 AD known as the Medieval Warm Period. During the Little Ice Age, global temperatures dropped by around 4 degrees Celsius. This cooling was likely caused by decreased ocean circulation and increased volcanic activity. The colder climate led to failed harvests and famine across Europe. It also contributed to the spread of plague and helped the Vikings in Greenland to die off. The Little Ice Age had significant historical impacts and demonstrates humanity's vulnerability to climate change.