Geoengineering is the deliberate and large-scale intervention in the Earth's climate system in an attempt to mitigate the adverse effects of global warming. Now that climate emergency is upon us, claims that geoengineering is inevitable are rapidly proliferating. How did we get into this situation where the most extreme path now seems a plausible development? Is it an accurate representation of where we are at? Who is this 'we' who is talking? What options make it onto the table? Which are left out? Whom does geoengineering serve? Why is the ensemble of projects that goes by that name so salient, even though the community of researchers and advocates is remarkably small? These are some of the questions that the thinkers contributing to this volume are exploring from perspectives ranging from sociology and geography to ethics and indigenous studies. We set out this diverse collection of voices not as a monolithic, unified take on geoengineering, but as a place where creative thinkers, students, and interested environmental and social justice advocates can explore nuanced ideas in more than 240 characters.