The laws of thermodynamics, especially the second law, underpin the least action, maximum power, and maximum entropy production principles. They boil down to depleting energy gradients as rapidly and efficiently as possible. As varied forms and pathways of energy flows and transformations “explore” their possibility space, those that achieve the gradient depletion and efficiency criteria are retained in the short term and recur repeatedly over time. The explorations that do not meet these criteria tend to fade and vanish and do not show a pattern of recurrence. These principles can be grouped together as forms of thermodynamic selection. Thermodynamic selection occurs in general processes such as turbulent fluid flows and atmospheric energy exchanges. These are manifested in global phenomena such as atmospheric and ocean general circulation, evaporation and the hydrologic cycle, and teleconnection patterns such as ENSO. Thermodynamic selection is also evident at more local scales, e.g., in fluvial and estuarine processes.