Final answer:
The abrupt period of cooling around 13,000 years ago is called the Younger Dryas, after the Arctic flower Dryas that became widespread in Europe at this time. This event had a profound impact on human history, affecting patterns of migration, settlement, and agriculture.
Step-by-step explanation:
The abrupt period of cooling around 13,000 years ago is known as the Younger Dryas, named after a genus of Arctic flower called Dryas that became widespread across Europe during this period. This event, which interrupted the general warming trend after the last Ice Age, is evidenced by a significant body of palynological (pollen) and geological data. The Younger Dryas is recognized as a stark reminder of how quickly climate conditions can change, shaping human history and migration patterns.
For example, during this time there was a significant reduction in solar activity, and the colder conditions that ensued affected the ability of Norse explorers to maintain regular contact with their outposts in North America. This cold phase represents a time when significant climatic changes occurred, leading to adjustments in human settlement and agricultural practices. Indeed, these shifts in climate have periodically altered the course of human events, as seen in later periods like the Little Ice Age that had profound impacts on agriculture and population dynamics.