An immense volcanic eruption in 1257 A.D. affected our entire planet. But which volcano exploded?

A titanic volcanic eruption in 1257 A.D. spewed out colossal amounts of ash, sulfur, and glassy pumice, and affected climate over the entire planet. It was one of the largest if not the largest eruption in the past 7,000 years, and evidence of it can literally be found from pole to pole.

But... what volcano erupted?

Weirdly, until recently no one knew just which volcano on Earth had exploded. This had geologists scratching their heads until just a few years ago, when multiple lines of evidence...