Last week I attended a conference at the Berlin-Brandenburg Academy of Sciences and Humanities. Organized by the German research council DFG academics from various disciplines gathered for three days at the Climate Engineering Research Symposium in the old but nicely refurbished building at the Gendarmenmarkt. The arches and pillars on the right side of the conference room still show the bullet holes from the last war. The hanging glass ceiling floats perfectly above the heads of the audience, with ever so tiny spaces between the panels, illuminated from above. This example of (low-tech) engineering and craftsmanship could be seen as a symbol of the floating fleet of aircraft deployed to inject particles into the stratosphere to cool the planet.