The Ocean Is a Carbon Toilet. Marine Heat Waves Are Clogging It.

Scientists have discovered that marine heat waves in the northeastern Pacific Ocean, particularly off Alaska, are disrupting the ocean’s natural carbon sequestration process. Normally, tiny organisms like phytoplankton absorb carbon dioxide and produce fecal pellets that sink to the seafloor, effectively locking away carbon and regulating atmospheric CO2 levels. However, prolonged heat waves from 2013 to 2015 and 2019 to 2020 altered the composition of phytoplankton and zooplankton, reducing the ocean’s ability to transport carbon to deeper waters. This disruption, described as “clogging the ocean’s carbon toilet,” threatens the ocean’s role in mitigating climate change, as oceans absorb about a quarter of human-generated CO2 emissions. The study, based on a decade of data from autonomous Biogeochemical Argo floats, highlights regional variations but raises concerns about broader impacts of warming seas on marine ecosystems and global climate regulation. The findings underscore the interconnected risks to ocean health, atmospheric carbon levels, and human reliance on marine resources.