1150 A.D. - Quilotoa, Ecuador Erupts; Volcanic Explosivity Index (VEI) = 6
1150 A.D. Little Ice Age (First Peak) Begins
1259 A.D. - Very large eruption, Origin Unknown. Twice the size of the Mt.Tambora eruption in 1815 A.D. - this would make a Volcanic Explosivity Index (VEI) = 8 or more; possibly qualifying as a Super Volcanic Eruption.
Antarctica ice core data; Norwegian tree rings; England and Europe - numerous references to dark skies and unseasonable cold, one obscure reference to pillar of fire in western sky; Chinese reference to pillar of fire in southern sky; Indonesian description - near Krakatau - magma rose in a miles wide column into the troposphere lasting for some days before subsiding, according to refferences.
1452 A.D. - Kuwae, Vanuatu, New Hebrides Arc Erupts; Volcanic Explosivity Index (VEI) = 6.
1460 A.D. - Little Ice Age (First Peak) Ends
I witnessed the Mt. St Helen's eruption; it looked pretty massive to me. Which four “massive” tropical volcanoes which took place in a 50 year period that supposedly triggered the little ice age are they referring to in the study? Are they referring to actual events or events that they believe happened because of their simulation results? The article does not make it clear and it certainly makes no reference to the three events you mention that were spread over a 300 year period not a "50 year" period.