The Southern Hemisphere subtropical anticyclones (SAs) are important features of the Earth's climate. A broad consensus among Coupled Model Intercomparison Project phase 3 and phase 5 climate models suggests an intensification of summer SAs over SH oceans in association with the increase in greenhouse gas concentrations in the atmosphere. Diagnostic and modeling analyses conducted here demonstrate that the strengthening of the SAs is primarily caused by enhanced diabatic heating over continents and cooling over oceans in austral summer. This enhancement of Southern Hemisphere near-surface SAs identified here together with the enhancement of their Northern Hemisphere counterparts as suggested by Li et al. (2012) indicates increasingly important roles played by SAs in modulating weather and climate on regional and global scales.