Carbon Uptake and Seasonal Traits in Antarctic Remineralisation Depth (CUSTARD)

Lead Research Organisation: University of Plymouth
Department Name: Sch of Geog Earth & Environ Sciences

Abstract

The surface ocean is home to billions of microscopic plants called phytoplankton which produce organic matter in the surface ocean using sunlight and carbon dioxide. When they die many of them sink, taking this carbon into the deep ocean, where it may be stored for hundreds to thousands of years, which helps keep our climate the way it is today.
In general terms the size of the effect they have on our climate is linked to how deep they sink before they dissolve - the deeper they sink, the more carbon is stored. This effect is particularly important in the northern part of the Southern Ocean where the pattern of ocean currents means that the difference between shallow and deep dissolution controls whether this carbon is locked away from the surface ocean for just a few years or for centuries. This is because the area is a junction in the ocean circulation. Stacked up on each other from the surface to the seafloor at almost 5km depth are four oceanic 'motorways', taking water to different parts of the global ocean. The motorway that the carbon is dissolved into determines how long it will be kept away from the atmosphere.
For this reason, if we want to understand the role of this northern part of the Southern Ocean in regulating global climate we need to understand both how big carbon uptake is at the ocean surface and also how deep sinking material dissolves. Unfortunately we don't understand either well; data are scarce in the Southern Ocean as the weather is poor and few commercial vessels pass through there. Consequently, our theories about the pattern of the fate of sinking carbon and what controls this are untested. As a result the models that we use for predicting future climate have massive uncertainty in this region. However, the evidence that we have suggests that changes in the depth of carbon dissolution are key to understanding how the system works.
In this project we will tackle this by making new observations in a remote region of the Southern Ocean using an exciting combination of robotic vehicles and sophisticated new sensors. We will make new observations of how much carbon the ocean takes up in this key motorway junction of the Southern Ocean. We will examine the processes that control the uptake of carbon and its fate, in particular how seasonal availability of nutrients can affect the make-up of the phytoplankton which changes the depth to which carbon sinks before being dissolved.
We will combine these observations with a novel modelling approach that allows us to run the ocean part of our climate model much faster than normally. This allows us to explore the consequences of the seasonal interplay between nutrients and phytoplankton found in our data. In particular, the model allows us to 'tag' carbon so that we can trace where it goes. In this way we can measure the amount of sinking carbon ending up on each motorway and how this varies through the year.
Together with observations of the seasonal changes in nutrients and sinking carbon the model will allow us to determine the key processes regulating carbon uptake in this important area. This will provide important information to those building the UK's climate model at a time when it is being developed to provide input to a future high profile report (from the IPCC) on the state of the world's climate.

Planned Impact

CUSTARD will engage fully with the other funded RoSES projects and NERC to ensure CUSTARD's impact plan is integrated with wider impact activities. In addition, CUSTARD will achieve impact in the following areas:

Climate prediction:
International agreements to limit the impact of anthropogenic climate change such as COP21 are based upon accurate and precise predictions of how the earth system will respond to potential scenarios of future greenhouse gas release. Our ability to predict future trajectories of atmospheric CO2 and climate is, in turn, strongly dependent on our ability to develop robust and accurate climate models that can quantitatively demonstrate their skill in reproducing the existing CO2 record. CUSTARD will contribute directly to two aspects of this.
First, CUSTARD will collect ocean CO2 flux data year-round in the chronically under-sampled Southern Ocean. Co-I Bakker is a key member of SOCAT (http://www.socat.info), the standard source of flux data globally and widely used for policy briefings (e.g. Pollution in the open oceans: 2009-2013. Boelens, R. et al., GESAMP reports and Studies 91) and climate model testing (e.g. ESMValTool (v1.0) - A tool for evaluation of Earth System Models in CMIP: Eyring, V., et al., 2016. Geoscientific Model Development 9, doi:10.5194/gmd-9-1747-2016).
Second, CUSTARD will provide mechanistic information on the controls on carbon uptake and redistribution in the Southern Ocean. The new insights generated in CUSTARD into the seasonal variability of production and remineralisation, and the implications for ocean carbon storage will be fed through existing links into ongoing development of UKESM2, the next generation UK Earth System model for the UK's contribution to future IPCC assessments.

Autonomous sensing:
Robotics and autonomous systems were identified by the UK government in 2013 as one of 8 great technologies that will help drive economic growth. This was followed by a large (£10 million) capitl investment into the MARS national facility. CUSTARD will thus be of interest to the growing community of AUV and sensors manufacturers and users, including agencies with marine monitoring obligations, e.g. Defra and CEFAS. We will hold a community workshop which will focus on best practice for using autonomous vehicles to derive information on carbon fluxes, which we will host at the NOC. Similar previous events have successfully attracted many representatives of AUV manufacturers, however, we will extend the reach to include stakeholders with a remit for ocean monitoring, such as Defra and CEFAS.

Technology:
A novel dissolved silica sensor developed by NOC's Ocean Technology and Engineering group will be deployed during CUSTARD. This is the first autonomous sensor, suitable for the marine environment, capable of measuring in situ silicate, a key component of ocean biogeochemistry. The successful demonstration of this sensor to provide high quality silicate measurements autonomously over an extended period of time will be exploited to generate interest in commercialisation of the sensor.

Science communication:
The CUSTARD team includes co-I Henson, an experienced and effective communicator to general audiences, having participated in multiple public engagement and schools activities, ranging from on-screen contributions to BBC4 TV series 'The Spectrum of Science', to being a panel member at Royal Institution debates, to lectures at the Cheltenham Science Fair, to exhibiting events aimed at school children such as the Big Bang science fair.
Project staff will also be encouraged to undertake public engagement training, such as through the public engagement courses run by NERC or Sense about Science. In addition, a new public engagement activity will be designed as part of CUSTARD and used during the annual Ocean and Earth day held at NOC (attracts > 3000 visitors) and at other events.

Publications

10 25 50
 
Description Dissolved iron is known to be a limiting micronutrient in many regions of the Southern Ocean, meaning its availability in seawater restricts the growth of phytoplankton at the base of the Antarctic food chain. The recent research cruise onboard the RRS Discovery (December 2019-January 2020) allowed a full-depth transect to be completed in the CUSTARD study area of the SE Pacific and Southern Ocean (55-60S). Iron was sampled and analysed on board and initial results indicate that it is severely depleted in the upper waters of this region of the southern ocean. Due to the remoteness of this region, annual upward transport of iron from deepwaters is vital to sustain the ecosystems and will vary year on year depending on the mixing of these deepwaters to the surface. Specific deep water long-range sources of iron were also discovered on this expedition and are currently being verified.
Exploitation Route International agreements to limit the impact of anthropogenic climate change such as COP21 are based upon accurate and precise predictions of how the earth system will respond to potential scenarios of future greenhouse gas release. Our ability to predict future trajectories of atmospheric CO2 and climate is, in turn, strongly dependent on our ability to develop robust and accurate climate models that can quantitatively demonstrate their skill in reproducing the existing CO2 record.

The iron data from WP3 will contribute directly by:
(i) Full data entry into British Oceanographic Data Centre (BODC)
(ii) Entry of data into global biogeochemical models linking iron availability to natural carbon cycling and storage (e.g. ongoing development of UKESM2, the next generation UK Earth System model for the UK's contribution to future IPCC assessments.)
(iii) Inform the global community (e.g. Earth System models for UK's contribution to future IPCC assessments)
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Chemicals,Environment,Leisure Activities, including Sports, Recreation and Tourism,Government, Democracy and Justice

 
Description ARIES PhD Studentship for Isobel Turnbull 
Organisation Natural Environment Research Council
Country United Kingdom 
Sector Public 
PI Contribution Drs Milne and Ussher put forward a studentship proposal which was accepted and funded by NERC'S ARIES Doctoral Training Partnership. This studentship was initially linked to the PICCOLO project, which is currently delayed, and therefore a research plan for CUSTARD was put together to facilitate Isobel's participation in CUSTARD and the necessary equipment sourced.
Collaborator Contribution Isobel has greatly contributed to this partnership. She is actively engaged and has successfully collected novel samples for analysis. The results from these samples could add a new dimension to the overall initial objectives of CUSTARD by providing additional information concerning iron biogeochemical cycling.
Impact The studentship is a multidisciplinary research collaboration involving both chemistry and biology (microbial ecology).
Start Year 2019
 
Description Hydrothermal Iron supply to the southern ocean 
Organisation National Oceanography Centre
Country United Kingdom 
Sector Academic/University 
PI Contribution An unexpected result of the CUSTARD field work was the identification of an iron enriched hydrothermal plume entering the SO. Dr Birchill, Dr Milne and Dr Ussher are responsible for the chemical characterization of this plume
Collaborator Contribution We are working with collaborators to establish the likey fate of this plume.
Impact mulit-disciplinary- marine geochemistry, marine physics
Start Year 2020
 
Description Antarctic CUSTARD cruise blog entries and twitter feeds (Dec 2019-Jan 2020) 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Regular blogs and twitter feeds were made during the Antarctic research cruise including a blog specific to studying trace metals and iron biogeochemistry
Year(s) Of Engagement Activity 2019,2020
URL https://roses.ac.uk/2020/01/13/trace-metals-on-custard
 
Description Attended Ocean Obs 19 conference, Hawaii 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Attended Ocean Obs 2019 conference to discuss the challenges to ocean observing systems in coming decace
Year(s) Of Engagement Activity 2019
URL http://www.oceanobs19.net/
 
Description Host session at internation conference- Goldschmidt 2019, Barcelona 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Dr Birchill hosted a session on technological developments in the field of automated measurements in aquatic environments. This took place at Goldschmidt 2019 meeting, Barcelona, attented by over 4000 delegates from around the globe.
Year(s) Of Engagement Activity 2019
URL https://goldschmidt.info/2019/
 
Description Participation in EU meeting in UNESCO headquarterrs on Global Ocean Observation (First International AtlantOS Symposium 25-28 March 2019 at UNESCO Headquarters, Paris) 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact Participation in discussion of the future of international efforts for ocean observation in the Atlantic Ocean
Year(s) Of Engagement Activity 2019
URL https://www.atlantos-h2020.eu/first-international-atlantos-symposium/
 
Description Presentation at national confernce 'Advances in Marine Biogeochemistry' 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presented at AMBIO conference, collection of marine biogoechemists in the UK. Dr Birchill invited to the University of Bristol to establish collaboration based on work presented.
Year(s) Of Engagement Activity 2019
URL https://www.challenger-society.org.uk/Advances_in_Marine_Biogiochemistry
 
Description Presented at international workshop on carbon uptake and sequestration in the ocean 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presented to an expert group assembled for a meeting at the National Oceanography Centre, Southampton. Requested to lead trace metal harmonization effort between different projects.
Year(s) Of Engagement Activity 2019
URL https://noc-events.co.uk/biarritz-workshop
 
Description Weekend open day and school visits at the University of Plymouth 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact Marine/polar research section in talks to parents and school children visitng for opendays at the chemistry programme (typically 6 per year)
Year(s) Of Engagement Activity 2019,2020