IE is still in a formative stage, with a diversity of definitions and understandings of scope of application. A consensus is emerging around certain key themes, however, there are critical areas of divergence among industrial ecologists. The following discussion is based upon our content analysis of over twenty-five definitions, supported by a similar analysis by researchers at University of Michigan.

Common themes -- an emerging consensus?

The majority of discussions of industrial ecology tend to agree on the following elements.

• Industrial ecology is a systems approach drawing upon methods for analysis
  and synthesis from systems science.
  
  
• This systems approach focuses upon the interaction of industrial systems
  and the ecological systems (local to global) of which they are a part.
  
  
• IE seeks to redesign industrial activities to reduce the ecological impact of
  human activity to levels natural systems can sustain.
  
  
• IE is interdisciplinary, linking the research and planning of many fields,
  including ecology, engineering, economics, business management, and public administration and law, among others.
  
  
• IE studies the flows of materials and energy through the economy, ranging
  from those of an industrial or public facility to the planet. It seeks strategies
  to increase the efficiency and reduce the impact of these flows. (This study is
  often termed "industrial metabolism".)
  
  
• Industrial ecology seeks transformation from a linear, wasteful economy to a closed-loop system of production and consumption. In such a system
  industrial, governmental, and consumer discards would be reused, recycled,
  and remanufactured at the highest values possible.
  
  
• IE enables creation of short-term innovations with awareness of their
  long-term impacts. Similarly, it enables local decision-making with
  awareness of broader regional and global impacts.
  
  
• IE is a means of balancing environmental protection with economic and
  business viability. This balance must be dynamic, adapting to new
  knowledge about industry's impacts and nature's responses.
  
  
• IE is a major component in "the science of sustainability", with the role
  of designing the transition path for industrial activities, broadly defined.
  It offers an objective (though complex) foundation for coordinating
  design of public policy in environmental, technical, and environmental
  realms.
  

Areas of divergence

While there is a fair degree of consensus on the elements of industrial ecology
just listed, there is also much divergence as to its scope and emphasis. In part
this is simply a matter of specialization within the field. But the following
differences often go the heart of how different researchers define IE.

• Timescale: Some industrial ecologists emphasize incremental change in
  existing systems. Others speak of far reaching transformation of industry
  and society.
  
  
• The ecosystem model: With some, a very popular theme is modeling
  industrial systems upon the principles and dynamics of ecosystems.
  However, some ecologists and many engineers question the usefulness
  of this approach.
  
  
• Materials flows: Some industrial ecologists focus on the task of increasing
  the efficiency and reducing the impacts of materials flows in industry and
  society. In some articles the whole field appears to be little more than this.
  
  
• Scope of application: Much discussion focuses on change in manufacturing industries, while other practitioners emphasize that IE is relevant to
  agricultural, service and financial industries, as well as the design and management of public policy, infrastructure, and facility operations. A
  few extend IE's domain to the realm of consumer behavior.
  
  
• Key ecological concerns such as biodiversity, carrying capacity, and
  restoration are emphasized in the work of university researchers but
  are seldom mentioned by more technically oriented industrial ecologists .
  (Allenby & Graedel's definition does emphasize carrying capacity. 1995)
  
  
• Some see institutional change as a fundamental component of IE. Others
  discount this, emphasizing the centrality of technical innovation to IE.
  
  
• Materials choices: The shift from non-renewable, synthetic materials to
  renewable bio-materials is a central concern for some industrial ecologists.
  Others focus on improving the environmental performance of petroleum
  based and other synthetic materials.
  

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