NERC GW4+ DTP Projects 2020: (Changing Planet) Oceans losing breath: is anthropogenic climate change to blame for recent oceandeoxygenation?

Oxygen is essential to biological and chemical processes in the ocean. Over the last 50 years low-oxygen zones which are hostile to marine life have expanded by an area about the size of the European Union [1]. Hot-spots of ocean deoxygenation have also developed closer to home in commercially important European shelf waters of the North Sea and Baltic Sea [e.g. 2]. Ocean deoxygenation is an expected
consequence of on-going climate change and ocean warming due to the reduced solubility of oxygen at higher temperature and reduced mixing of surface and deep waters [3]. However the driving processes responsible for recent declines in ocean oxygen, both on the shelf and in the open ocean, remain elusive [4]. Given the major threat posed to marine life by ocean deoxygenation, asking to what degree humandriven climate change is causing the observed changes is essential to bring about policy action and safeguard ecosystems. The overall aim of this project is to better understand the physical and biological drivers of recent ocean deoxygenation in the coastal and open ocean. The project will employ state-of-the-art climate models, such as those provided by international modelling centres as their contributions to the next IPCC report, to determine the expected global “fingerprint” of human driven ocean deoxygenation. These model
“fingerprints”, or climate signals, will be compared and contrasted with the observational record of ocean oxygen using detection and attribution statistics [5] to establish the role of anthropogenic climate change. Climate fingerprints of ocean deoxygenation will also be determined for European shelf sea hot-spots such as the Southern North Sea using regional models developed during the NERC/DEFRA Shelf Seas Biogeochemistry Research Programme at PML, and potentially widening this to the global shelf seas with co-supervisor Paul Halloran at the University of Exeter. This project will benefit from strong international collaborations on ocean deoxygenation. Other specific research objectives for this project can be tailored to the students interests.