Single-celled algae in the ocean known as coccolithophores play an important role in the marine carbon cycle when they take up bicarbonate from seawater to build their shells. Coccolithophore numbers have been increasing globally in recent years, meaning their influence is growing, even as scientists still don't fully understand the factors driving their explosive growth. One explanation could be changes to the alkalinity of ocean water, specifically, greater amounts of bicarbonate available for the tiny creatures to use.
