The ideas brought together here as Emergy Systems developed over more than seven decades. Their history is one of expanding scale and synthesis, from early studies of energy flow and biogeochemical cycles, through ecosystems and regions, to human economies, nations, and the coupled systems of humanity and nature.
The development was not simply the progression of a theory from one idea to another. Much of it occurred through research on real systems. Springs, coral reefs, tropical forests, estuaries, wetlands, regions, economies, and nations provided settings in which ideas about energy, organization, feedback, and system behavior could be confronted with observation and measurement. Field studies revealed patterns; systems diagrams required relationships to be made explicit; models explored their consequences; and experiments tested how systems responded to changing inputs and disturbance.
Major research programs were especially important. They brought together investigators working on many different components of a system while systems diagrams and models provided a means of integrating their work at the level of the whole. These projects therefore did more than apply existing theory. They became important settings in which concepts, methods, and models were tested, modified, and extended.
As this work developed, its scope expanded beyond ecosystems. Ecological and human processes increasingly were examined within the same systems framework. Systems Ecology provided the theoretical foundation, while Ecological Engineering, Energy Analysis, and eventually Emergy and Environmental Accounting developed as closely related areas of theory and application. These developments overlapped rather than occurring as separate stages.
The historical perspective presented here follows this development chronologically. It traces the interaction of ideas, research programs, methods, and applications that contributed to Emergy Systems. H.T. Odum is necessarily central to the account, but the history also includes the students, colleagues, collaborators, and research programs through which the work developed.
Sections
2.2 Whole Systems and Energy Flow
2.3 From Ecosystem Energetics to Systems Ecology
2.4 Systems Ecology and Human Systems
2.5 Energy Analysis, Quality, and Hierarchy