Reflecting upon 10 years of geoengineering research: Introduction to the Crutzen + 10 special issue

Abstract Ten years ago, Nobel laureate Paul Crutzen called for research into the possibility of reflecting sunlight away from Earth by injecting sulfur particles into the stratosphere. Across academic disciplines, Crutzen's intervention caused a surge in interest in and research on proposals for what is often referred to as ?geoengineering??an unbounded set of heterogeneous proposals for intentionally intervening into the climate system to reduce the risks of climate change. To mark the 10-year anniversary of the publication of Paul Crutzen's seminal essay, this special issue reviews the developments in geoengineering research since Crutzen's intervention and reflects upon possible future directions that geoengineering research may take. In this introduction, we briefly outline the arguments made in Paul Crutzen's (2006) contribution and describe the key developments of the past 10 years. We then proceed to give an overview of some of the central issues in current discussions on geoengineering, and situate the contributions to this special issue within them. In particular, we contend that geoengineering research is characterized by an orientation toward speculative futures that fundamentally shapes how geoengineering is entering the collective imagination of scientists, policymakers, and publics, and a mode of knowledge production that recognizes the risks that may result from new knowledge and that struggles with its own socio-political dimensions.