A Monte Carlo approach to understanding the relative importance of Greenlandic vs Antarctic forcings of global sea level during the last glacial cycle

The relative importance of Northern Hemisphere versus Southern Hemisphere forcing(s) of global sea level during the last glacial period is hotly debated. There is enticing evidence for both cases but the question remains open. As an exercise, we investigate something approaching the simplest possible situation of global ice volume that can be 'forced' by Greenland or Antarctic temperature records or a mixture of both. An advantage of using such a simple approach or model is that we are able to run tens of thousands of possible variations in order to optimise the potential of any given temperature record to simulate the global sea-level curve for the last glacial cycle. The analysis provides insight into not only possible drivers of former sea level but also the records as paleoclimate proxies. The results indicate that neither the Antarctic nor the Greenland record alone can simulate the complete stratigraphy of the global ice-volume record. Instead, during different phases of the last glacial cycle, the Antarctic and Greenland signals play either leading or secondary roles in terms of simulating the stratigraphy. We suggest that the analysis implies that the transitions between 'Greenland and Antarctic dominance' are fundamental drivers of transitions between glacial and interglacial climate states.