海洋 かいよう 酸素 さんそ事変 じへんであれば
kaiyōmusansojihendeareba

Noun
Da Copula

The "-eba" conditional form ("if/when…") of 海洋無酸素事変

1. If/When the Oceanic Anoxic Event…; If the Oceanic Anoxic Event were to happen…

Ba Conditional