In 1973, C.S. “Buzz” Holling published “Resilience and stability of ecological systems.” This ultimately seminal paper, and true paradigm shift, was greeted with a resounding silence, and then skepticism (Holling, personal communication). The skepticism centered upon the lack of evidence for alternative stable states in most systems – due, largely, to a lack of adequate time series data to detect regime shifts. As more data became available, evidence increasingly mounted supporting the existence of alternative states for many ecological—and eventually social—systems.  Building upon this increasing acceptance of the concept of resilience, in 1997 Holling (with collaborator Lance Gunderson and others) founded and received significant funding to establish the Resilience Network (currently the Resilience Alliance: https://www.resalliance.org/). The Resilience Network was an early attempt to establish connections among ecologists, social scientists and economists to investigate alternative stable states and the concept of resilience in social-ecological systems. 

The Resilience Network (Alliance) was successful and productive, and members and participants have produced a large and influential body of scientific literature, focusing on both theory and practice (Web of Science keyword search on “ecological resilience” returns 140 publications in 1997, and more than 40,000 in 2018). In the early 2000s, the Director of an international NGO addressed the Resilience Alliance and made the following observation: The Resilience Alliance has achieved success, the concept of ecological resilience is largely accepted and is widely known - - but the Alliance no longer owns the ideas or controls the messaging or science of resilience. That observation was accurate. Resilience has exploded as a concept but has also come to mean many different things to different scholars and practitioners. Because the term resilience had a history, especially in psychology and medicine, before Holling coined “ecological resilience”, there has been an undercurrent of confusion between the two primary definitions – that of “bounce back” (resiliency), and that of resilience as an emergent property of systems (ecological resilience). Additionally, the term has become a buzzword, that is often used interchangeably with sustainability. Competing ideas are healthy for scientific progress, but confusion and lack of certainty regarding meaning and intent are not. Both definitions can be reconciled within an ecological resilience framework, because social-ecological systems can bounce back from disturbance. However, bounce back alone fails to account for non-stationarity and thresholds in social-ecological systems. Ecological resilience accounts for social-ecological systems that transition into alternate states, potentially never to return to a previous state, as well as systems that bounce back.   

Words matter, and theory matters. In our paper (https://www.nature.com/articles/s41893-019-0401-4), we highlighted the differences between ecological resilience and resiliency, and concluded that the two concepts are ultimately reconcilable, with resiliency subsumed within ecological resilience. The core concepts of ecological resilience have withstood the test of time and given rise to novel insights and approaches, that are well suited for dealing with the challenges facing humankind in the face of accelerating environmental change. 

- Craig Allen, Brian Chaffin, Ahjond Garmestani