Emergent computaion [Forrest] is a type of computation that is bottom-up and not globally nor totally programmed. Only local information or very limited amount of information is used for a unit of computation. However, certain global information structure, which is often unexpected, is emerged from this computation. This process is analogical to so-called self-organization in chemical processes, such as Belusov-Zabotinsky reaction [Prigogine] or physical processes, such as lazer oscillation [Haken]. Emergent computation has been deeply studied in Artificial Life .
A complex system usually has a layered structure. The system looks and behaves very differently in microscopic or lower level than in a macroscopic or higher level. A system based on emergent computation is not programmed in higher level. The information structure, or the result or solution of the computation, is basically built from microscopic level in a bottom-up manner, and the macroscopic structure is emerged from the microscopic computation. However, top-down information flow, which is emergent, is sometimes also important.
If the system is programmed in higher level, it cannot adapt to a change of requirements because the requirements are built-in. It is probably not possible to adapt to a change of environments too. However, a system based on emergent computation can (probably) adapt to a change of requirements or enviroments.
More detailed philosophical background of CCM, such as the relation to the self-organization paradigm , synergetics  or the systems philosophy  is discussed by Kanada and Hirokawa .