The Southern Ocean – that stormy and remote sea that separates the Antarctic from Africa, Australia and Latin America – is one of the hardest places on Earth to carry out scientific research. But there is a growing realisation that in the era of climate change, we need to understand it better.
RoSES (Role of the Southern Ocean in the Earth System) – a five-year, £7-million programme led by NERC and running until 2022 – is designed to improve assessment of the Southern Ocean carbon sink and increase understanding of the role of the Southern Ocean in 21st-century global climate change.
Mark Brandon is professor of polar oceanography at the Open University and Chair of the Programme Advisory Group for the RoSES programme. He says: “The Southern Ocean has long been seen as a backwater, but we now realise that the polar oceans are the front line of climate change impact on the planet.”
Brandon has been heavily involved in BBC science projects with Sir David Attenborough, including Blue Planet which had a 500 million global audience. As a result of that success, he says, people now realise that anything that goes into the ocean, such as waste plastic, may finish up in some remote region of the Earth.
Sir David and Mark Brandon. Credit: The Open University
This global movement of matter is the reason for modern interest in the Southern Ocean, which is central to the three-dimensional flow of water through the world’s seas. The ocean currents carry heat, and they absorb and release greenhouse gases as they change temperature.
The Southern Ocean has a key role in this global carbon cycle, because the waters there absorb carbon. As Brandon says, “Although the Southern Ocean is stormy and remote, we have to understand it if we are to understand and control climate change.”
Brandon explains that RoSES faces three main challenges. “The first is to understand the Southern Ocean carbon sink as It exists today. This work is being done by a group led from the University of East Anglia. Then we need to look at where carbon goes in the Southern Ocean. This involves two projects: one looking at shallower waters, called CUSTARD, and another concentrating on the deep ocean, called PICCOLO.” These two are led from the National Oceanography Centre in Southampton and UEA respectively.
The third priority is to develop what Brandon terms “policy-informing” insights from this research. Here the task is to produce outputs that climate policymakers can use. To do this, RoSES includes two projects on the Southern Ocean as a sink for carbon.
One based at the University of Liverpool, and called SARDINE, is finding out whether the waters of the Southern Ocean are saturated with carbon dioxide, or are capable of dissolving more. Brandon says that this is a “big unknown that is important to tie down” for the Intergovernmental Panel on Climate Change.
Ship to shore
The RoSES projects involve both research cruises in the Southern Ocean, and UK-based modelling. To get a grasp of the current state of the Southern Ocean, UEA is carrying out a desk-based study called SONATA, while the British Antarctic Survey is performing research in the Southern Ocean involving 20 research groups in the UK. Continuing the musical theme, this part of the programme is called ORCHESTRA.
The task of mapping carbon flows in the Southern Ocean involves research cruises for each part of the project, as well as modelling work and biology experiments carried out in the UK. Brandon says that this adds up to “a vast amount of work on ships and planes, and through remote sensing technology.” By contrast, the production of policy-informing outputs will call for what he terms “hardcore modelling,” based on data from the earlier phases of the programme.
While today’s policymaking tends to be about carbon dioxide and other greenhouse gases in the atmosphere, Brandon points out that there is far more carbon in the deep oceans then in the air we breathe, dragged into the deep by ocean circulation in the Arctic and Antarctic.
“This carbon can be buried in deep sediments,” says Brandon, “or can come back to the surface and be released.” In the first case, it is removed more or less permanently from the atmosphere, but in the second, it can be back in circulation much more quickly.
This issue is already a UK priority, and Brandon expects there to be follow-up work in this complex area of research. Part of the picture is seasonal variation. The animals that absorb carbon into the ocean are most active when there is more warmth and light.
“We know that more carbon is absorbed by plants during the Northern hemisphere spring, and we expect the same effect in the Southern Ocean. But at the same time, the winter weather is rougher, so we get more mixing of surface waters.” That too is likely to mean more carbon being absorbed.
For the climate as for many other aspects of the Earth system, the present is the key to the past. So it is important to understand how the climate of the Southern Ocean region has changed over time. The ORCHESTRA project has provided ocean-based data on past climates. In addition, Brandon points out, the UK and the US are leading drilling campaigns at the Thwaites Glacier on the Antarctic mainland to gather data on past climates and to understand how those glaciers are melting.
He says: “That drilling should give us information on climate in the past 10,000 to 100,000 years. This will be very helpful for RoSES, whose priority is the next 100 years.” But he warns too that the present day is a difficult time for making predictions. “Today’s science is based on what happened in the last ice age, which is very different from the current anthropogenic effect [of global warming].”
This adds up to a complex scientific picture. But Brandon is clear about the overall message: it is vital for the human race to emit less carbon. “We are already seeing the effects of climate change. Because the oceans take up heat, we do not feel the full impact. But we can already see the warmer oceans influencing wind patterns and weather systems.”
He adds that while research will say in detail where carbon goes in the Earth system and where the big impacts are, temperature rises in the Arctic have already reached the 1.5 degree limit targeted in the 2015 Paris Agreement.
Turning trailblazing science into agenda-setting TV
Scientists have played a key role in the development of TV that inspires environmental action, generates export income and boosts British influence worldwide. All three academic consultants working on the BBC’s Blue Planet II series were funded by the Natural Environment Research Council. 88% of viewers said the series inspired them to change their behaviour.