Why do some Martian dust storms, in some Mars years, expand to reach planet-encircling status, while the majority do not? In what ways do the largest regional events differ from those that become global? Comparisons of observations from these two categories of events may help answer these questions. The dust storm season of 2018, which included a global-scale dust event, was preceded by five successive dust storm seasons in which only regional-scale events were observed. The recent record thus presents an opportunity for making quantitative comparisons between regional-scale and global-scale dust events. Observations by the Mars Climate Sounder, on board the Mars Reconnaissance Orbiter spacecraft, provide unique 4D information on temperatures and aerosol loading of the Mars atmosphere, to altitudes of >80 km. Available MCS observations span the past eight Mars years. We have previously employed MCS observations to characterize the evolution in latitude, longitude, and altitude of atmospheric dust clouds during the initiation phase of the 2018 global event. Other atmospheric fields provide complementary information. For instance, observed changes with time in atmospheric ‘dynamical heating’ also help characterize the response of the Mars atmosphere to added dust loading. In this process, the atmosphere in regions far removed from the locations where dust is lifted may be warmed by adiabatic compression within the descending branches of Hadley-like meridional circulation cells. We will present and interpret MCS observations of these and other phenomena for selected large regional-scale dust events of Mars Years 29-33 (from 2009 through 2017), and draw comparisons with observations obtained during the 2018 global event. We will additionally explore the implications of the results within the context of current hypotheses for the triggering of the largest dust storms on sub-seasonal time scales.