Atmospheric carbon dioxide concentrations in 1610 decreased for reasons unknown; high mortality in the Americas after the European arrival may be the reason, but this decrease could have been at least in part the consequence of the Huaynaputina eruption. The vast tephra fallout of the eruption fell in part over the sea; the fertilizing effect of the tephra may have induced a draw-down of carbon dioxide from the atmosphere. The Huaynaputina eruption has also been associated with perchlorate deposition in Greenland.