The iron hypothesis posits a role for increased supply of mineral aerosol to the ocean surface during glacial periods in driving atmospheric CO2 lower; that changes in CO2 and climate strongly affect dust supply raises the possibility of feedback. Here I take a systems view in analyzing the properties and implications of such a feedback and consider three primary state variables that can be related empirically to each other: dust supply, atmospheric CO2, and climate (surface air temperature). The results of this analysis suggest that the dust-CO2-climate feedback is primarily an intraglacial phenomenon, when it can account for about a third of the temperature variability recorded in Antarctic ice cores. Since glacial-interglacial cyclicity prior to ca. 800 kyr BP is characterized by the absence of a full glacial state (such as the Last Glacial Maximum), it is possible that destabilization of climate by the marine iron cycle is fundamental to the differences between 41 kyr and 100 kyr climatic regimes. The critical role played by the state of the land surface in this feedback also has implications for the longer-term evolution of the Earth system during the Cenozoic.