Was breaking the taboo on research on climate engineering via albedo modification a moral hazard, or a moral imperative?

The topic of increasing the reflectivity of the Earth as a measure to counteract global warming has been the subject of high-level discussions and preliminary research since several decades, though prior to the early 2000s there was only very limited research on the topic. This changed in the mid-2000s, particularly following the publication of a special section of Climatic Change with a lead paper by Crutzen [2006], which posited the idea of stratospheric aerosol injections as a possible solution to a policy dilemma. The discussions around the publication of Crutzen [2006] demonstrated how contentious the topic was at that time. The special section of Climatic Change contributed to breaking the taboo on albedo modification research that was perceived at that time, and scientific publications on the topic have since proliferated, including the development of several large national and international projects, and the publication of several assessment reports over the last decade. Here we reflect on the background and main conclusions of the publications in 2006, the developments since then, and on some of the main developments over the next decade that we anticipate for research and dialogue in support of decision-making and policy development processes.