Abstract

This review focuses on the increasing vulnerability of the world ocean to multiple anthropogenic stresses in the latter half of the twentieth century and the first decade of the twenty-first century. The multiple stresses, which affected the world ocean in the latter half of the twentieth century, could have been controlled on a timescale of decades, had governments and their subjects chosen to do so. In the twenty-first century, the timescale of remediability has been observed to shift from decades to centuries and even to millennia. The major additions to the suite of multiple stresses consist of the combined impacts of changing ocean thermal structure and increasing acidification, both of which are the results of increased anthropogenic CO2 emissions. The consequences of these recent changes are assessed. The assessment makes clear collectively what is known and unknown and what responses are available to human social systems to adapt to these accelerating changes.