The concentration of carbon dioxide (CO2) in oceans is typically measured in parts per million (ppm). As of recent measurements, the CO2 concentration in ocean surface waters is roughly 400-425 ppm, mirroring atmospheric CO2 levels to a large extent due to the solubility of CO2 in seawater.
However, the ocean is also experiencing changes due to factors like ocean acidification, which is influenced by increased atmospheric CO2 levels. Projections for future CO2 levels in the ocean depend on various factors, including future greenhouse gas emissions scenarios. Under significant emission scenarios, ocean CO2 concentrations could increase, with projections suggesting levels could reach between 600 and 1000 ppm by the end of the 21st century if current trends continue.
These figures can vary based on geographic location, depth, and other environmental factors. Overall, monitoring and modeling efforts continue to provide updates on these trends as more data becomes available.