Anthropogenic perturbations from fossil fuel burning, nuclear bomb testing, and chlorofluorocarbon (CFC) use have created useful transient tracers of ocean circulation. The atmospheric 14C/C ratio (triangle 14C) peaked in the early 1960s and has decreased now to pre-industrial levels, while atmospheric CFC-11 and CFC-12 concentrations peaked in the early 1990s and early 2000s, respectively, and have now decreased by 10%-20%. We present the first analysis of a decade of new observations (2007 to 2018-2019) and give a comprehensive overview of the changes in ocean triangle 14C and CFC concentration since the WOCE surveys in the 1990s. Surface ocean triangle 14C decreased at a nearly constant rate from the 1990-2010s (20 parts per thousand/decade). In most of the surface ocean triangle 14C is higher than in atmospheric CO2 while in the interior ocean, only a few places are found to have increases in triangle 14C, indicating that globally, oceanic bomb 14C uptake has stopped and reversed. Decreases in surface ocean CFC-11 started between the 1990 and 2000s, and CFC-12 between the 2000-2010s. Strong coherence in model biases of decadal changes in all tracers in the Southern Ocean suggest ventilation of Antarctic Intermediate Water was enhanced from the 1990 to the 2000s, whereas ventilation of Subantarctic Mode Water was enhanced from the 2000 to the 2010s. The decrease in surface tracers globally between the 2000 and 2010s is consistently stronger in observations than in models, indicating a reduction in vertical transport and mixing due to stratification. The ocean contains many dissolved gases that can be measured by sampling ocean water from ships. Some of these dissolved gases are changing over time because their atmospheric concentrations are changing. By measuring these changes in the ocean, we can learn about ocean transport and mixing, which is an important factor regulating climate change. We describe ocean measurements from the past three decades of radiocarbon in dissolved inorganic carbon, that was affected by nuclear bomb testing, and of chlorofluorocarbon gases, CFCs, that were banned in the 1990s due to their destructive effects on the ozone layer. The measurements show how their oceanic distributions have changed, as a result of their atmospheric histories and the patterns of ocean uptake and transport. By comparing the measurements with ocean models, we can identify biases in the models that affect how well future climate change can be predicted. In the most recent decade, the presence of all three tracers is shown to be decreasing in the upper ocean, a reversal of the preceding decades. Also in the most recent decade, the decrease in surface tracers is stronger in the observations than the models, suggesting a change to upper ocean mixing and stratification. Recent trends in upper ocean Delta 14C, pCFC-11, and pCFC-12 are negative, reflecting their decreasing atmospheric trends Increases in triangle 14C are only observed in a few places over 2000-2010s, showing oceanic bomb 14C uptake has stopped and reversed Model-data Delta 14C and chlorofluorocarbon differences could be consistent with decadal ventilation changes and large-scale stratification or model errors
