Oxygen is fundamental to ocean biogeochemical processes, with deoxygenation potentially reducing biodiversity, and disrupting biogeochemical cycles. This paper develops and implements a new inverse method to decompose oxygen change into its constituent parts by linking each process to concomitant changes in temperature and dissolved inorganic carbon (DIC). They apply this method to a GO-SHIP repeated section of the North Atlantic Ocean. They find that alterations in remineralisation, either local or upstream, are responsible for up to half of the total oxygen decrease seen in the upper 2000 m between 1992 and 2015. This method could be repeated on any dataset, observations or model, that includes temperature, DIC, and oxygen concentration data.

The paper contributes to our knowledge of the impact of marine heat waves on ecosystems, a subject that is topical and that we know little of. The impact on coccolithophores is important for carbon uptake. The impact of MHW more generally on algal blooms is also important for higher trophic levels, the wider ecosystem, and for commercial interests such as aquaculture. The study gives useful confirmation that the environmental ranges defined by O’Brien et al for coccolithophore blooms do seem to apply even in these anomalous MHW conditions and in two separate regions.

This is an important contribution to the science surrounding the Atlantic Meridional Overturning Circulation (known as AMOC), in particular with regard to observations and methods. This work may have strategic relevance for planning observations in the future. It also represents an interesting effort at incorporating artificial intelligence (AI) technology into obtaining optimal results from observational data analysis.

This paper in the Ocean Science Jubilee Special Issue is a multidisciplinary review of silicon in the ocean (and in fact also in the earth system). It presents "everything you ever wanted to know about silicates but were afraid to ask". In addition to its scientific excellence and thoroughness as a review, it is also noteworthy for being entirely conceived and written by a group of early career researchers who decided to work together on this topic. We commend their initiative!