Which 1883 volcanic eruption caused atmospheric cooling and vivid red sunsets worldwide?

The 1883 eruption of Krakatoa caused atmospheric cooling and vivid red sunsets worldwide.

Krakatoa was a volcanic island in the Sunda Strait between Java and Sumatra, in what is now Indonesia. A series of eruptions culminated on 27 August 1883, when enormous explosions destroyed much of the island and generated devastating tsunamis. More than 36,000 deaths were attributed primarily to the tsunami, making the disaster one of the deadliest volcanic events in recorded history.

The eruption injected ash and sulfur-bearing gases high into the atmosphere. Sulfur dioxide formed sulfate aerosols that scattered sunlight, producing unusually colorful sunsets and lowering global temperatures for several years. Reports of brilliant skies appeared in many parts of the world, and the effects were observed by artists and scientists. The original volcano’s collapse formed a caldera; a new volcanic cone, Anak Krakatau, emerged in the caldera during the twentieth century. Krakatoa is sometimes called Krakatau in Indonesian usage, and both forms appear in English references.