I will provide a dynamics-centred overview of how the coupling between the ocean’s geophysical, dynamical, and biochemical processes connects timescales of half a billion years to the present day through processes spanning the global scale to sub-centimetre turbulence. Over hundreds to a few millions of years, Earth’s interior dynamics (e.g. plate tectonics) inform the role of the oceans in the climate system by reshaping the anatomy of ocean circulation and impacting the global carbon cycle in not-well-understood fashions. On timescales of millions to tens of thousands of years (especially over the past few tens of millions of years), ocean-cryosphere coupling played a key role in shaping the ocean’s role in the climate system. On shorter timescales, dynamical and biochemical processes and their tight coupling generate climate feedbacks that connect millennial to daily timescales. I will provide examples of such processes and couplings. and highlight the importance of considering their history in the design of Earth System Models and the emerging Digital Twins of Oceans. As we know from the Marvel Universe (and dynamical systems and chaos theories!), the multiverse is real: climate bifurcations and tipping points can be sensitive to climate history. Our modelling efforts must be conscious of that, and emphasis needs to remain on understanding the underlying phenomenology, especially in the age of AI and ever-growing computational power.

Photo: “4 phytoplankton communities, illustrating ocean circulation and turbulence patterns—credit NASA.”