The IMOS Southern Ocean Time Series (SOTS) acquires high-frequency, autonomous, multi-trophic observations of Southern Ocean air-sea exchange, biological production, and carbon export in the subantarctic region south of Tasmania. This is achieved using two deep-water moorings: the Southern Ocean Flux Station (SOFS) focuses on heat, oxygen, and CO2 fluxes across the air-sea interface and the physical conditions and biological processes that modulate them; the Subantarctic Zone (SAZ) sediment trap mooring focuses on quantifying the transfer of carbon to the ocean interior by sinking particles, i.e. the biological carbon pump. The IMOS-SOTS observatory has established baselines for seasonal changes in hydrography, air-sea exchange, biological productivity, and export from observations between 2010 and present (SOFS) and between 1997 and present (SAZ). Given emerging global interest in marine carbon dioxide removal (mCDR), the recognition of the importance of long-time series in the ocean as a means of quantifying natural variability and monitoring change has grown. A requirement for any mCDR approach, is a robust understanding of natural baseline variability against which to assess deliberate perturbation. The IMOS-SOTS observatory is used here to illustrate the potential for IMOS to play a role in assessing the effectiveness of ocean-based climate solutions in Australia and elsewhere.