Steps and missteps on the path to a 1665–1668 CE date for the VEI 6 eruption of Long Island, Papua New Guinea

Estimates of the age of the widespread Tibito Tephra and the VEI 6 eruption of Long Island, Papua New Guinea, have been based on genealogical records derived from oral histories of a ‘time of darkness’, the voyage of William Dampier who named Long Island in 1700 CE, radiocarbon, palaeomagnetic and 210Pb dating, and efforts from around the world to associate the eruption with a number of sulphur spikes in Greenland and Antarctic ice cores that were not linked to better-known eruptions. In total, there have been more than one hundred estimates of the timing of the eruption, with appraisals ranging from the late 16th century to the early 20th century. Some of these estimates have been based on solid science, some have ignored or been unaware of constraints on the possible eruption date imposed by the need to make an allowance for revegetation of the island before or after the observations of Dampier and other navigators, and some have tried to relate the eruption to the misdirected observation of sunsets over London in 1665. This account describes, more or less in chronological order, the narrowing of the supposed eruption date to the latter half of the 17th century, an early record suggesting a possible link to a 1667 acidity peak in the Crête, Greenland ice core, further constraints imposed by a renewed round of radiocarbon assays, and a final suggestion of a likely but not proven 1665–1668 eruption based on recent Antarctic and Greenland ice cores. We also elucidate missteps along the way introduced by the reliance on Royal Society of London records from the late 19th and 20th centuries and the role of the Victorian novelist William Harrison Ainsworth and Daniel Defoe's early-17th century accounts of bubonic plague in London in 1665 in leading us down dead-end pathways.