Industrial Ecology: The role of manufactured capital in sustainability

In 1992 PNAS presented a Special Feature with 22 contributions from a colloquium entitled “Industrial Ecology,” held at the National Academy of Sciences of the United States in Washington, DC (1). In these articles Industrial Ecology was presented as an approach to understand and ultimately optimize the total material cycles of industrial processes (2). This PNAS issue presents the second Special Feature on Industrial Ecology, offering the opportunity to reflect on the original goals and approaches and to compare them with Industrial Ecology’s achievements and its pertinent role within sustainability science. The motivation to promote a new field as originally expressed in the contributions of the 1992 Special Feature is soberingly topical (3, 4): (i) the recognition that human alterations of the Earth System are progressing at an unprecedented pace; (ii) the insight that humankind has become a planetary force; and (iii) advocacy for a real-world sustainability transition that would be as fundamental as the industrial revolution of the 18th century. Since the first Special Feature in 1992, the pace of growth in global greenhouse gas emissions, material use, and energy use has not slowed down or stopped, but rather has accelerated, especially after the year 2000 (5⇓–7). Human-induced alterations of the Earth System have reached such a scale (8, 9) that a new term for the current geological epoch, the Anthropocene, was proposed (10). Climate-sensitive tipping elements of the Earth System have been detected and described (11). Those tipping elements (such as the Indian monsoon, the Amazon rainforest, or the Greenland Ice Sheet) have been stable since the beginning of the Holocene but have the potential to irreversibly flip into fundamentally different regimes once triggered by a global mean temperature above certain thresholds. Some of those thresholds appear to be within the reach …