In the summer of 1783, an unusual dry fog blanketed large parts of the northern hemisphere. The fog brought with it bloodred sunsets, a foul sulfuric odor, and seemingly, a host of other peculiar weather events. Inspired by the Enlightenment, many naturalists attempted to find reasonable explanations for these occurrences. Between 8 June 1783 and 7 February 1784, unbeknown to the contemporaries outside of Iceland, a 27-kilometer-long fissure volcano erupted, producing the largest volume of lava released by any volcanic eruption on planet Earth in the last millennium. In Iceland, the eruption led to the death of one-fifth of the population. The jetstream carried its volcanic gases further afield to Europe and beyond. "The Laki Eruption of 1783" is an environmental history of the Laki eruption, which combines methods of historical disaster research, climate history, global history, history of science, and geology in an interdisciplinary approach. Icelandic Laki-sized flood lava eruptions have a statistical recurrence period of 200 to 500 years; it is crucial to understand their consequences so that we can prepare for the next one. A volcanic eruption of this scale could be disastrous for our modern, globalized, and interconnected world.