Ralph Keeling: Oxygen trends in Atmosphere and Ocean. What do we know?

September 2016: Professor Ralph Keeling ( Scripps Institute for Oceanography, USA) speaks at The Royal Society event, Ocean ventilation and deoxygenation in a warming world.

Abstract
Human activities are causing systematic decreases in the O2 content of both the atmosphere and the oceans. The atmospheric loss is driven primarily by the burning of fossil-fuels while the oceanic loss is driven primarily by warming-induced reductions in O2 solubility and slowing of ocean circulation, i.e. reduced ventilation.

Oceanic deoxygenation could have potentially large environmental consequences, particularly if continued warming leads to an expansion of hypoxic or suboxic waters, as suggested by some models. Measurements of O2 in both the ocean and atmosphere are recognized as having considerable diagnostic value, and this has fuelled an expansion of measurements and measurement capabilities in recent years.

The oceanic O2 measurements have helped to establish the magnitude and mechanisms of recent O2 changes. The atmospheric O2 measurements have helped to quantify global carbon sinks and to provide a window into sources of oceanic O2 variability via the tracer atmospheric potential oxygen (APO ~ O2+CO2).

APO measurements show strong signals related to ocean ventilation which vary from year to year, and the well-measured global APO trend can potentially be used to quantify the global oceanic deoxygenation rate. This talk will highlight results from oceanic and atmospheric O2 measurements in the context of ongoing changes in ocean ventilation and deoxygenation. https://royalsociety.org/science-events-and-lectures/2016/09/ocean-ventilation/