Significance The Younger Toba Tuff is the largest volcanic eruption of the past 2 million years, but its climatic consequences have been strongly debated. Resolving this debate is important for understanding environmental changes during a key interval in human evolution. This work uses a large ensemble of global climate model simulations to demonstrate that the climate response to Toba was likely to be pronounced in Europe, North America, and central Asia but muted in the Southern Hemisphere. Our results reconcile the simulated distribution of climate impacts from the eruption with paleoclimate and archaeological records. This probabilistic view of climate disruption from Earth’s most recent supereruption underscores the uneven expected distribution of societal and environmental impacts from future very large explosive eruptions.