Fundamentals: oxygen and the ocean

Chairs Professor John Shepherd CBE FRS, University of Southampton, UK Professor John Shepherd CBE FRS, University of Southampton, UK Professor John Shepherd CBE FRS, University of Southampton, UK

Professor John Shepherd CBE FRS, University of Southampton, UK Membership status unknown No primary institution

John Shepherd is a Professorial Research Fellow in Earth System Science in the National Oceanography Centre at the University of Southampton. He has worked on a wide range of environmental issues, including the transport and deposition of atmospheric sulphur dioxide, the dispersion of tracers in the deep ocean, the assessment and control of radioactive waste disposal in the sea, the assessment and management of marine fish stocks, and the ocean’s role in climate change. He was the first Director of the Southampton Oceanography Centre from 1994-1999, and from 2001-10 was a Deputy Director of the Tyndall Centre for Climate Change Research, and was elected a Fellow of the Royal Society in 1999 and awarded a CBE in 2010. He was a member of the DEFRA Science Advisory Council for seven years and chaired the DECC Science Advisory Group from 2009 to 2013. He has been involved as a member or reviewer in several of the Society’s science policy studies and chaired the study on Geoengineering the Climate in 2009. More recently he has been involved in preparing several public documents on climate science including the Royal Society Summary of the Science and the recent joint RS/NAS briefing document.

09:05-09:40 Recent oxygen trends in the atmosphere and the oceans: what do we know? Professor Ralph Keeling, Scripps Institute for Oceanography, USA Abstract Human activities are causing systematic decreases in the O 2 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 O 2 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 O 2 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 O 2 measurements have helped to establish the magnitude and mechanisms of recent O 2 changes. The atmospheric O 2 measurements have helped to quantify global carbon sinks and to provide a window into sources of oceanic O 2 variability via the tracer atmospheric potential oxygen (APO ~ O 2 +CO 2 ). 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 O 2 measurements in the context of ongoing changes in ocean ventilation and deoxygenation. Listen to the audio (mp3) Show speakers Professor Ralph Keeling, Scripps Institute for Oceanography, USA Professor Ralph Keeling, Scripps Institute for Oceanography, USA Professor Ralph Keeling, Scripps Institute for Oceanography, USA

Professor Ralph Keeling, Scripps Institute for Oceanography, USA Membership status unknown No primary institution

Ralph is a climate scientist whose research interests include climate change, changes in atmospheric composition, ocean biogeochemistry, and carbon cycling. Ralph received a B.S. in physics from Yale University in 1979, and a Ph.D. in applied physics from Harvard University in 1988. He was the first to demonstrate that the oxygen concentration of the global atmosphere is decreasing due to the burning of fossil-fuels and has directed a program to track this decrease since 1989. Since 2005 he has also directed the Scripps CO2 program which sustains the iconic record of carbon dioxide at Mauna Loa and other sites, begun by his father, Charles D. Keeling. He is engaged in ongoing research to refine estimates of sources and sinks of carbon dioxide using atmospheric measurements. Ralph is an active participant in teaching and advising graduate students at the Scripps Institution of Oceanography at UC San Diego. He has given keynote addresses to the American Geophysical Union (AGU), the G8 Legislators and Business Leaders Climate Change Forum, and given the Bolin Lecture in Stockholm in 2011. Keeling has received the Rosenstiel Award in marine and atmospheric chemistry, the Humboldt Research Award, and is a Union Fellow of the AGU.

10:00-10:40 Ocean impacts of climate change: the IPCC and beyond Professor Monika Rhein, IUP-MARUM, University of Bremen, Germany Abstract The ocean is a main player in the climate system. Owing to lack of historic observations, reliable estimates of, for instance, oceanic heat budgets were only possible after 1970. Since that time, ocean warming accounted for more than 90% of the increase in the Earth’s energy inventory, while only a small fraction heated the atmosphere, the continents, and was used for melting of sea ice, glaciers and ice sheets. The ocean also plays a major role in the long-term variability of the atmospheric temperature, and could for several years obscure the mean global temperature increase, mainly caused by anthropogenic emissions of CO2. The ocean warming also has consequences for the uptake of anthropogenic carbon by enhancing the vertical density stratification in the ocean und thus potentially reducing the ventilation of intermediate, deep, and bottom water. Changes in the intermediate water ventilation in the subpolar North Atlantic occurred from the 1990s to today, a period well covered with oceanic observations. Although caused by natural variability of atmospheric modes on multiannual time scales (i.e. the NAO), this region provides a test bed to study the processes and mechanisms to improve our understanding of the changes expected under global warming. Listen to the audio (mp3) Show speakers Professor Monika Rhein, IUP-MARUM, University of Bremen, Germany Professor Monika Rhein, IUP-MARUM, University of Bremen, Germany Professor Monika Rhein, IUP-MARUM, University of Bremen, Germany

Professor Monika Rhein, IUP-MARUM, University of Bremen, Germany Membership status unknown No primary institution

Monika Rhein made her PhD in physics before she turned to physical oceanography. She was a Heisenberg Fellow and associate professor at the IFM Kiel (now named GEOMAR), Germany. After a short period at the Institute of Baltic Research (Rostock, Germany), she moved in 2000 to the University Bremen, and since then leads the physical oceanography department. Her interest is in climate relevant processes in the ocean. Her scientific contributions focus on the Atlantic, and encompass, for instance, studies of time scales of water mass ventilation and circulation. She was Coordinating Lead Author for the fifth IPCC Assessment Report, published in 2013, and responsible for Chapter 3 “Observations: Ocean” in Working Group 1.