Climate-driven variability of the Southern Ocean CO sink.

The Southern Ocean is a major sink of atmospheric CO, but the nature and magnitude of its variability remains uncertain and debated. Estimates based on observations suggest substantial variability that is not reproduced by process-based ocean models, with increasingly divergent estimates over the past decade. We examine potential constraints on the nature and magnitude of climate-driven variability of the Southern Ocean CO sink from observation-based air-sea O fluxes.

Using the atmospheric CO growth rate to constrain the CO flux from land use and land cover change since 1900.

We explore the ability of the atmospheric CO record since 1900 to constrain the source of CO from land use and land cover change (hereafter "land use"), taking account of uncertainties in other terms in the global carbon budget. We find that the atmospheric constraint favors land use CO flux estimates with lower decadal variability and can identify potentially erroneous features, such as emission peaks around 1960 and after 2000, in some published estimates. Furthermore, we resolve an offset in the global carbon budget that is most plausibly attributed to the land use flux.

Impact of Changing Winds on the Mauna Loa CO Seasonal Cycle in Relation to the Pacific Decadal Oscillation.

Long-term measurements at the Mauna Loa Observatory (MLO) show that the CO seasonal cycle amplitude (SCA) increased from 1959 to 2019 at an overall rate of 0.22   0.034 ppm decade while also varying on interannual to decadal time scales.