We would like to draw your attention to the recent IUCN review report on "Ocean deoxygenation: Everyone's problem." This report is the largest peer-reviewed study so far into the causes, impacts and possible solutions to ocean deoxygenation. Ocean regions with low oxygen concentrations are expanding, with around 700 sites worldwide now affected by low oxygen conditions – up from only 45 in the 1960s. In the same period, the volume of anoxic waters – areas completely depleted of oxygen – in the global ocean has quadrupled, according to the report. The ocean is expected to lose 3–4% of its oxygen inventory globally by the year 2100 under a business-as-usual scenario, but the global average masks local changes that are predicted to be, for example, more severe in mid to high latitudes. Most of the losses are predicted to be concentrated in the upper 1000 m of the water column, which is richest in marine biodiversity. The full report and summary for policy makers are available from: https://www.iucn.org/theme/marine-and-polar/our-work/climate-change-and-oceans/ocean-deoxygenation

At the same time we would like to inform you about a related OceanObs'19 Community White Paper on "Multidisciplinary Observing in the World Ocean’s Oxygen Minimum Zone Regions: From Climate to Fish — The VOICE Initiative." The Variability of the Oxycline and its ImpaCt on the Ecosystem (VOICE; http://www.ioccp.org/voice) initiative, supported by IOCCP since its beginning in 2017, aims to demonstrate how societal benefits drive the need for integration and optimization of biological, biogeochemical, and physical components of regional ocean observing related to eastern boundary systems (EBSs). VOICE chose to focus on the upper oxycline (transition between high and low oxygen waters) which is fundamentally important for the ecosystem structure and can be a useful proxy for multiple observing objectives connected to EBSs that neighbour oxygen minimum zones. In this paper, we present a first readiness level assessment for ocean observing of the oxycline in EBS around the globe. The paper can be accessed openly and freely at: https://www.frontiersin.org/articles/10.3389/fmars.2019.00722/full