Wanderlust World Wanderlust World Seawater near Antarctica exhibits exceptionally high acidity (low pH) due to the upwelling of ancient, carbon-rich deep water. This natural process brings CO₂-saturated water to the surface, lowering carbonate ion availability. The effect peaks in summer, threatening marine calcifiers — pteropods, corals, shellfish — that build shells from calcium carbonate. This makes the Southern Ocean a sentinel for ocean acidification impacts, offering early warnings for global marine ecosystems under rising atmospheric CO₂.