Final answer:
The Younger Dryas and the 8.2 ka climatic events were likely caused by disruptions in ocean circulation and changes in the Earth's climatic systems, possibly exacerbated by volcanic activity and shifts in Earth's orbit.
Step-by-step explanation:
Both the Younger Dryas and the 8.2 ka event are believed to have been caused by large-scale disruptions to the Earth's climatic systems.
Though the exact mechanisms are not fully understood, they are associated with sudden and significant changes in temperature and are believed to be linked to factors such as changes in ocean circulation patterns, possibly triggered by the influx of large volumes of freshwater into the North Atlantic.
Similar such events like the Little Ice Age may have been further influenced by volcanic eruptions releasing aerosols into the atmosphere, reflecting solar energy back into space and shifts in the Earth's orbit. These complex interactions led to global cooling, glacier expansion, and other significant environmental impacts.