Some scientists argue mitigation alone can no longer prevent dangerous levels of atmospheric CO2 and propose directly intervening in the climate system to counter the effects of greenhouse gas induced warming. Can we successfully manipulate the climate system to avoid dangerous climate change? Do we understand the global climate system well enough to determine the feasibility and risks involved? In this year’s Lorne Trottier Public Science Symposium, climate scientists and a historian of science will discuss the scientific and social ramifications of geo-engineering the climate.