Geoengineering schemes have been proposed to temporarily counteract global warming, as nations work to implement mitigation strategies to reduce greenhouse gas emissions. While many general geoengineering concepts have been put forward in recent years, no concrete proposals that address the range of scientific and social issues related to such activities have been submitted for consideration. This session focuses on climate modification through the manipulation of solar energy input to Earth, but also discusses ocean fertilization. Examples of the former include the injection of reflective aerosols into the lower stratosphere and seeding of marine clouds to modify their albedo, and placement of mirrors beyond the atmosphere to deflect incoming sunlight. Speakers will address the efficacy of proposed schemes as well as their side effects, which could include unwanted regional climate changes, ozone depletion, and reduction of solar power and blue skies. In addition, the practical, historical, and ethical dimensions will be discussed. Speakers will also discuss the fundamental problem that since a significant fraction of anthropogenic carbon dioxide will remain in the atmosphere forever (more than 1,000 years), geoengineering to reduce solar radiation would have to be maintained for a very long time, until current carbon dioxide emissions are eliminated and a large amount of the carbon dioxide already in the atmosphere is captured and sequestered.