Under-Ice Phytoplankton Blooms in the Chukchi Sea Are Sending Carbon to the Seafloor Faster Than Expected

New research from the Chukchi Sea shows Arctic phytoplankton blooms can grow in dense populations under thick sea ice and then sink to the seafloor much faster than scientists expected. During a 2023 expedition, Stanford researchers found under-ice blooms up to 10 times more concentrated than open water blooms sampled later in the season. In some areas, a collision of ocean currents pushed the carbon rich plankton down about four times faster than the normal sinking rate. The findings matter for the ocean carbon cycle. When phytoplankton sink quickly, more carbon can reach sediments instead of being eaten near the surface. But the study also notes uncertainty. Warmer freshwater from melting ice could block nutrients and limit future blooms. The authors say small scale physics like fronts may play a bigger role in global carbon transport than previously recognized.