Abstract:
One of scientific grand challenges to global climate for the balance of the 21st century are the projected changes to the feedbacks between ocean and terrestrial carbon reservoirs and climate (WCRP, 2017.. The Southern Ocean is a major contributor to this challenge. It already accounts for 50% of the CO2uptake and 75% of the heat uptake by the ocean and accounts for most of the uncertainty in global estimates of air-sea fluxes. The scientific challenge is how will this main driver of global carbon budgets change in the coming decades and what does our learning of its contemporary dynamics help us anticipate the 21stcentury trajectory of carbon fluxes and storage in the Southern Ocean? The major insight of the past 7 years from global ocean carbon science was that the carbon uptake by the SO has a decadal mode with very large amplitude of 0.6 -1Pgy-1. This is large enough to influence the long-term trend and the impact of mitigation measures. However, presently we neither understand the drivers nor do earth system models have ability to simulate the interannual – decadal variability of CO2 fluxes in the SO. Although global models agree on the mean annual fluxes they diverge on the seasonal cycle of the fluxes of CO2. This points to mechanistic differences that can influence the climate forcing sensitivity of the internal variability and trends. Here we examine how SOCCO research is contributing to these problems in three main ways: firstly, by taking a high-resolution approach to develop new observational product constraints to the interannual variability of the seasonal cycle of CO2 fluxes; secondly, by using the seasonal mode to advance the understanding for the mechanisms behind carbon biases in CMIP5 models and thirdly, by examining the role of fine scale dynamics in understanding the climate sensitivity of CO2 fluxes as well as the biological carbon export fluxes. We then propose how this learning will help us contribute to the global challenge of improving the understanding and projections of the role of the Southern Ocean in global climate in the future. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.
