Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA)

Start date
1 April, 2016

Climate change is one of the most urgent issues facing humanity and life on Earth.

Whilst our everyday understanding of climate concerns the warmth of the atmosphere, the ocean is critical in controlling how our planet’s climate changes. This is because the ocean absorbs vast quantities of heat and carbon dioxide which, if they had remained in the atmosphere, would have greatly accelerated the rate of climatic change there.

ORCHESTRA logo_horizontal_16cm_300dpi

Since the industrial revolution, the global ocean has absorbed around 30% of anthropogenic (human-produced) CO2 emissions. In addition, 93% of the total extra heat in the Earth System since the onset of global warming has been absorbed by the ocean. This is equivalent to around 170 terawatts, the power that would be required for each of the 7 billion people on Earth to continuously operate sixteen 1500 watt hairdryers.

Improving climate prediction thus requires us to learn more about how the ocean works, and how it interacts with the atmosphere to control the split of heat and carbon between them. A key region in this context is the Southern Ocean, the vast sea that encircles Antarctica.

Although the Southern Ocean occupies only around 20% of the total ocean area, it absorbs about three-quarters of the heat that is taken into the ocean, and approximately half of the CO2. This is because of its unique pattern of ocean circulation: it is the key region globally where deep waters upwell to the surface from 1-2 km down, allowing new water masses to form and sink back into the ocean interior. This exposure of old waters to the atmosphere, and the production of new waters, is fundamental to the exchanges of heat and carbon with the atmosphere. More information on how the Southern Ocean influences global climate can be found in a recent article in Nature; click here.

Figure1-southern ocean circulation schematic
Graphic of the overturning circulation in the Southern Ocean, and the lateral flows around the Antarctic continent. (From Meredith, Geophysical Research Letters, 2016)

Despite this knowledge of the key role the Southern Ocean plays in global climate, there are many important unknowns. These include an incomplete understanding of the detailed mechanisms by which heat and carbon and transferred across the sea surface and drawn down into the interior, a lack of knowledge of the rates of these transfers and how they will change in future, and insufficient information of the distribution of the heat and carbon around the globe within the planetary-scale ocean circulation.

To address these issues, a new £8.4M programme funded by NERC has been created – ‘Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA)’. The project is led by the British Antarctic Survey, in partnership with National Oceanography Centre, British Geological Survey, Plymouth Marine Laboratory, the Centre for Polar Observation and Modelling (CPOM), the Sea Mammal Research Unit at the University of St Andrews and the UK Met Office, along with numerous national and international partners.

ORCHESTRA will span five years and use a combination of data collection, analyses, and computer simulations to radically improve our ability to measure, understand and predict the circulation of the Southern Ocean and its role in the global climate. It will make unique and important new measurements in the Southern Ocean using a range of techniques, including use of RRS James Clark Ross and RRS Sir David Attenborough, as well as deployments of autonomous surface and underwater vehicles, the BAS meteorological aircraft, and other innovative techniques for collecting data. It will also involve the development and use of advanced ocean and climate simulations, to improve our ability to predict climatic change in coming decades.


Schematic of the ORCHESTRA fieldwork. Black lines are major ship-based expeditions; pink sectors are flying areas for the BAS meteorological aircraft; red ellipse denotes a deep-ocean mooring cluster; green splodge is the region to be covered by instrumented seals; yellow stars are nominal areas of deployment for autonomous ocean vehicles. The entire region will also have data coverage from profiling floats and satellite measurements.

Full details of the ORCHESTRA programme, including the detailed descriptions of the fieldwork and model developments, are available in the Case for Support. This was approved for funding by NERC following international peer review and assessment by the NERC Science Board.

This work was supported by the Natural Environment Research Council [ORCHESTRA, grant number NE/N018095/1].

For further details on ORCHESTRA, contact the Principal Investigator: Dr Emily Shuckburgh: emsh@bas.ac.uk

Our programme aim is to advance our understanding of, and capability to predict, the Southern Ocean’s impact on climate change via its uptake and storage of heat and carbon.

ORCHESTRA will significantly reduce current uncertainties concerning how the uptake and storage of heat and carbon by the ocean influences global climate, by conducting a series of unique fieldwork campaigns and innovative model developments. This is a leading-order challenge of great societal relevance and strategic importance to NERC, but progress is currently hampered by poor provision of data with which to improve understanding of the key processes and constrain their rates, and inadequate representation of the key dynamics in ocean and climate forecast models.

The area requiring the most urgent improvement is the Southern Ocean, where many of the controlling mechanisms and exchanges occur, and yet where data coverage is most sparse, dynamical understanding is weakest, and climate models show greatest biases and least realistic depictions of processes.

ORCHESTRA will address these issues using the UK’s world-leading capability and infrastructure in ocean and high-latitude research, including major ship expeditions, autonomous vehicle deployments and research aircraft campaigns, with the data collected used to improve model schemes and validate model outputs, and with the improved capability fed through to UK climate model development.

ORCHESTRA represents the first fully-unified activity by NERC institutes to address these challenges, and will draw in national and international partners to provide community coherence, and to build a legacy in knowledge and capability that will transcend the timescale of the programme itself.

Drake Passage Blog

24 November, 2016 by Yvonne Firing

Follow ORCHESTRA project scientist Yvonne Firing’s amazing fieldwork blog from the Southern Ocean here. On the 2016/2017 Drake Passage cruise on the RRS James Clark Ross, we sail south from …

The changing Southern Ocean: Heat and carbon

8 May, 2023

A series of studies on the Southern Ocean, which encircles Antarctica, reveal how it is changing. A special issue of the Journal Proceedings of the Royal Society, led by the …

Giant iceberg mission begins

2 February, 2021

A research mission to determine the impact of the giant A-68a iceberg on one of the world’s most important ecosystems departs from Stanley in the Falkland Islands today (2 February …

New field season begins

29 November, 2016

As spring returns to the southern hemisphere British Antarctic Survey (BAS) has started another research season which will take them over land, sea and ice in search of answers to …

RRS Sir David Attenborough

The RRS Sir David Attenborough, commissioned by NERC, built by Cammell Laird for operation by British Antarctic Survey, is one of the most advanced polar research vessels in the world.