What is the fine-grained topic of the following text: It was hypothesized that these shifts in historical upwelling intensity were related to trends hemispheric-scale climatic records that might impact Caribbean atmospheric and oceanic patterns such as the North Atlantic Oscillation (NAO), the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA), tropical cyclone (TC) strikes at the Blue Hole, and the average position of the Intertropical Convergence Zone (ITCZ). Only return the topic.
Relationship between historical upwelling intensity and large-scale climatic trends impacting Caribbean atmospheric and oceanic patterns.