There's been so much research on the iceberg armada events (Wikipedia Heinrich events) since the classic 1988 paper by Hermut Heinrich himself. There's a host of different data concerning the events, so why is still such a mystery? Here's an excellent introduction to the research carried out in slide show format Paleo Slide Set: Heinrich Events: Marine Record of Abrupt Climate Changes in the Late Pleistocene. Here's a 2009 report which links the events with abrupt changes in Indonesian waters Evidence for Indonesian Throughflow slowdown during Heinrich events 3–5. What's going on?