ENCORE (‘Encore is the National Capability ORchestra Extension’) is a one year extension of ORCHESTRA running from April 2021-March 2022  and will build upon, and extend, the original specific objectives of ORCHESTRA. ORCHESTRA has greatly improved our understanding of how the Southern Ocean exchanges and exports heat and carbon. In the process, new questions have been opened up, and the models, data products and tools developed by ORCHESTRA provide new avenues of inquiry into the still critical questions of how this vast ocean regulates our existing climate and may modify its potential future trajectories.

ENCORE will address these questions using the UK’s world-leading capability and infrastructure for ocean and high-latitude research, including ship expeditions and a research aircraft campaign. The existing and newly collected data will be used to validate and improve models developed under ORCHESTRA and to test ideas that have emerged over the last five years. As well as developing new scientific ideas, ENCORE will also strive to synthesise the knowledge generated by ORCHESTRA and complementary research programmes (e.g. RoSES, SO-CHIC, SOCCOM), bringing together data and models in order to improve the fidelity of UK climate model projections. The new understanding generated by ENCORE syntheses will be communicated to the international community through milestone international meetings, with a particular emphasis on setting priorities for more detailed assessments and future model developments.

ENCORE will continue the work pages from ORCHESTRA:

WP1: Delivery and extension of Southern Ocean surface flux analysis

WP2: Delivery and extension of Southern Ocean mixed layer analysis

WP3: Delivery and extension of Southern Ocean interior analysis

WP4: Management, dissemination and impacts

WP5: Overarching synthesis of Southern Ocean heat and carbon results and impacts.

Context

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 CO_2. 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.

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 continue to address these issues, the ENCORE project will be 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.

ENCORE ORCHESTRA will run for one-year and use a combination of data collection, analyses, and computer simulations to continue 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 the use of 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.

This work is supported by the Natural Environment Research Council [ENCORE, grant number NE/V013254/1]. For further details on ORCHESTRA, contact the Principal Investigator: Dr Andrew Meijers: andmei@bas.ac.uk