In early February, Tropical Cyclone Gabrielle passed over the Bellona Plateau in the Coral Sea, stirring up sediment from the shallow reefs there. Once the storm cleared, large swirls of carbonate sediment mixed into the deeper waters around the plateau. As the sediment sinks to depths of kilometers, it will dissolve into the deep ocean waters, eventually getting captured as part of sedimentary rocks. This is a critical step in the ocean’s carbon capture cycle.
Unfortunately, climate change is disrupting the ocean’s ability to capture carbon. An excess of carbon dioxide acidifies ocean waters, making it harder for creatures like corals and crabs to incorporate carbon into their bodies. That reduces sources for carbonate sediments like those seen here. Changes in ocean chemistry also affect where and how much carbonate can get dissolved. In short, ocean carbon capture has been an important process for Earth’s carbon cycle in the past, but the process is a slow one, and human activity has overloaded the ocean’s system in ways we don’t fully understand. (Image credit: A. Nussbaum; via NASA Earth Observatory)