The South Atlantic / Southern Ocean carbon sink: Is it significant, and is it changing over time?
Lead Research Organisation:
Royal Holloway University of London
Department Name: Earth Sciences
Abstract
This project is designed to determine how much carbon dioxide (CO2) is absorbed by the South Atlantic and neighbouring Southern Ocean, and how important this is in the global picture. We will achieve this by measurement of atmospheric CO2 and related species at several key islands, and on a commercial ship, and by use of the atmospheric data in modelling studies to determine the uptake (amount absorbed) and whether it is changing over time. Understanding the uptake of CO2 by the oceans is essential, if we are to meet the challenge of understanding global warming by greenhouse gases. This is because, of the CO2 we produce by burning fossil fuels, only about half stays in the atmosphere and contributes to global warming. Most of the remainder is taken up by the global oceans, which, while not contributing to global warming, does contribute to the harmful acidification of the oceans. But exactly how much is taken up, in which oceans, and how this uptake might change in a warming climate is unclear. One important region with the least clarity is the South Atlantic Ocean. By determining CO2 uptake of the South Atlantic and neighbouring Southern Ocean, this project will provide new information that will improve models of the global CO2 cycle. Our work will also contribute to answering the question if Southern Ocean CO2 uptake is changing under global warming. If it is, the implications are serious, and will affect future international emissions negotiations. Although CO2 is measured in seawater in the South Atlantic (for example by British Antarctic Survey), there are virtually no measurements of CO2 in the air above the region. This is because the inhabited islands are UK-owned, and the UK does not participate in international efforts to monitor atmospheric CO2, which are coordinated by the UN's Global Atmosphere Watch programme. Measuring CO2 from the atmosphere is perhaps more important, and more revealing, than measuring from the ocean. The reason is that the atmosphere mixes much faster than the ocean, and so measurements from any given station are representative of a region covering hundreds or even thousands of square kilometres, compared to only a few square kilometres for ocean water measurements. Our measurements will assess the differences in CO2 as air blows across the ocean and CO2 is absorbed by the water. CO2 varies greatly across the planet, both by latitude and by season, just as temperature varies. Our measurements will be carried out by a mixture of continuous observations and canister sampling. Continuous measurement of CO2 will be made at Ascension Island, near the equator, and at Falkland Islands, around 50S. CO2 will also be measured by canister sampling at these and three other UK islands. In addition, O2 concentrations and the isotope 13C in CO2 will be measured from the canister samples. Measuring these additional species tells us about the non-photosynthetic CO2, both fossil-fuel emissions and ocean uptake. Finally, we will also measure CO2 and O2 continuously onboard a commercial ship travelling across the Atlantic, to complement the data from the fixed stations. To interpret our measurements, we will carry out modelling studies. Presently, models based on ocean-water measurement seem to give different answers from the models based on the sparse atmospheric data. It is possible that CO2 uptake may change as the oceans warm, but much more evidence is needed. Our modelling studies will address these problems and will provide a much better understanding of how much CO2 is being taken up into the water in the region. Our work will help improve knowledge of one of the most poorly understood parts of the global carbon budget, the Southern Ocean. Better understanding of the atmospheric side of the equation will also be very helpful to oceanographers, because the South Atlantic and neighbouring Southern Ocean are a great global weather factory, and a key turning point of the ocean circulation system.
People |
ORCID iD |
Euan Nisbet (Principal Investigator) | |
David Lowry (Co-Investigator) |
Publications
Dlugokencky EJ
(2011)
Global atmospheric methane: budget, changes and dangers.
in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
Ganesan A
(2019)
Advancing Scientific Understanding of the Global Methane Budget in Support of the Paris Agreement
in Global Biogeochemical Cycles
Ganshin A
(2012)
A global coupled Eulerian-Lagrangian model and 1 × 1 km CO<sub>2</sub> surface flux dataset for high-resolution atmospheric CO<sub>2</sub> transport simulations
in Geoscientific Model Development
Greatwood C
(2017)
Atmospheric Sampling on Ascension Island Using Multirotor UAVs.
in Sensors (Basel, Switzerland)
Jones S
(2012)
Autocorrelation characteristics of surface ocean p CO 2 and air-sea CO 2 fluxes
in Global Biogeochemical Cycles
Manning AC
(2011)
Greenhouse gases in the Earth system: setting the agenda to 2030.
in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
Nisbet E
(2010)
Atmospheric science. Top-down versus bottom-up.
in Science (New York, N.Y.)
Nisbet E
(2016)
Rising atmospheric methane: 2007-2014 growth and isotopic shift
in Global Biogeochemical Cycles
Description | The measurements tracked an unexpected and sharp rise in Southern hemisphere methane (see Science Perspective). The Ascension Island (this project) and US American Samoa instruments were the only continuous high precision instruments operating in the equatorial belt. The reasons for this sharp rise are not fully understood but may be connected with much increased rainfall in the period in the Southern tropics. Work on the results is continuing to study the S Atlantic budget,and to track the extraordinary recent rise in tropical emissions. |
Exploitation Route | The measurements, when fully validated, will be important tropical inputs to global methane models. This use will be sustained as the time series becomes longer. |
Sectors | Environment |
Description | The work has contributed to a better understanding of the Southern Hemisphere's methane budget and the processes going on that have contributed to a sudden tropical growth spurt in methane. This may be an important feed-back in global climate change. The work has had impact on the scientific understanding of global change in the South. |
First Year Of Impact | 2011 |
Sector | Environment |
Impact Types | Societal |
Description | Award winner, 'The Engineer'/EPSRC Collaborate to Innovate awards. |
Form Of Engagement Activity | Engagement focused website, blog or social media channel |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Industry/Business |
Results and Impact | Award winner, The Engineer, Innovation prize |
Year(s) Of Engagement Activity | 2016 |
URL | https://www.theengineer.co.uk/collaborate-to-innovate-winners-annnounced/ |
Description | BBC World Service documentary - radio. "Discovery - cheating the atmsophere" |
Form Of Engagement Activity | A broadcast e.g. TV/radio/film/podcast (other than news/press) |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Participation in BBC World Service documentary "Disocvery - cheating the atmosphere". Long interview on the problems of assessing greenhouse gas emissions inventories for the United Nations Framework Convention on Climate Change - Paris Agreement. Broadcast several times in second week of Dec, 2017 |
Year(s) Of Engagement Activity | 2017 |
URL | http://www.bbc.co.uk/programmes/w3csvpfz |
Description | LONCON3 World Science fiction convention |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Several Activities - all invited. 1. Exhibition of methane measurement "Discover your inner cow" sampling methane in breath. 2. Panel discussion on climate in science fiction 3. Panel discussion on sci fiction and policy. |
Year(s) Of Engagement Activity | 2014 |
Description | NERC UnEarthed Showcase |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Schools |
Results and Impact | NERC UnEarthed Showcase event, Edinburgh. MOYA presentation on the Global methane budget, focussed on school age students. ~7000 schoolchildren and many members of the general public. 17,18,19 and 20 Novermber 2017 |
Year(s) Of Engagement Activity | 2017 |
URL | http://www.nerc.ac.uk/latest/events/archive/unearthed/ |
Description | Public Lecture: 56th Annual Bennett Lecture, Leicester Literary and Philosophical Society |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Public lecture - annual 'named' lecture of the Leicester Literary and Philosophical Society, Univ. of Leicester |
Year(s) Of Engagement Activity | 2015 |
URL | http://www2.le.ac.uk/hosted/litandphil/documents-1/transactions/transactions_2015 |
Description | Royal Holloway Science festival 2015 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Schools |
Results and Impact | Several activities - all coordinated by us; 1. fossil trail 2. Volcano exhibit and eruption 3. lecture 4. Gold panning |
Year(s) Of Engagement Activity | 2015 |