Photosynthesis in the ocean converts approximately 100 Gt of carbon dioxide (CO2) into organic matter every year, of which 5-15% sinks to the deep ocean. The depth to which this organic matter sinks is important in controlling the magnitude of ocean carbon storage, as changes in this flux attenuation depth drive variations in atmospheric pCO2 of up to 200 ppm. Efforts to produce global maps of flux attenuation have yielded starkly contrasting global patterns, blocking our understanding of ocean carbon storage and our ability to predict it. The bottleneck is our ignorance of the spatiotemporal variability of the processes that control flux attenuation. ANTICS will directly address this knowledge gap by using an innovative synthesis of cutting-edge in situ imaging, machine learning and novel data analyses to mechanistically understand ocean carbon storage. Use state-of-the-art imaging technologies, I will collect data on size, distribution and composition of organic matter particles and measure their sinking velocity in the upper 600 m across the Atlantic. I will design a neural network model that allows the conversion of in situ images into carbon fluxes, and develop analysis routines of particle size spectra that quantify the processes causing flux attenuation: remineralisation, physical aggregation/disaggregation, fragmentation/repackaging by zooplankton. By statistically linking these outputs to seasonality, depth, primary production and temperature, I will be able to determine which processes dominate under specific environmental conditions. This step change in our understanding will allow ANTICS to resolve flux attenuation spatially and temporally. I will use this pioneering knowledge to validate and inform the parametrization of the marine biogeochemical component of the UK’s earth system model used for carbon cycle forecasting in the next IPCC assessments.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

The seawater surface is the direct site of air-sea interactions and as such, the properties of the surface ocean may greatly influence the exchange of gases, heat and particles between the ocean and the atmosphere. Hydrophobic organic molecules are concentrated at the surface of the water to form the air-sea microlayer (ASML) that has been shown to harbour a different microbial community (bacterioneuston / BN) relative to the underlying water. Current methods of measuring biological properties of the ASML involve the initial removal and collection of BN. We propose to use a glass tube horizontally half immerged in surface water and sliced sideward through an intact ASML before being corked with two silicone bungs to become an incubation apparatus. The main aim of this proposed research is to develop a method capable of measuring metabolic rates of BN in the intact ASML, using radioisotopically labelled fatty acid tracers. Labelled gaseous metabolites of fatty acids will be collected by bubbling air through headspace of apparatuses and into traps selectively capturing CO2 or tritiated water. Because BN may influence physicochemical processes across the intact ASML, the effect on evaporation rates will be examined using tritiated water as a tracer. Comparisons will be made with samples where BN are not present, BN have been poisoned and samples where the ASML including BN has been removed with the aid of an ultra-thin nitrocellulose membrane. BN cells will be specifically stained with water-repellent dyes to separate them from planktonic cells using a cell sorting device / a flow cytometer. BN cells will be identified microscopically by selective labelling with taxon-specific molecular probes. These methods will be tested initially on marine bacterial cultures before using local seawater samples. It is anticipated that the methods and apparatus developed could be eventually used to measure BN metabolic rates in the intact oceanic ASMLs. The determined biogeochemical fluxes will be compared with physicochemical fluxes through the ASML to advance current understanding of the air-sea interface processes which affect global climate change.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Climate is currently changing mostly because of additional greenhouse gases, emitted through human activity, which are heating up the planet. Since future warming of climate is likely to cause damage to societies, governments are coordinating efforts to reduce greenhouse gas emissions to avoid these damaging consequences. However, despite the continuing rises in atmospheric greenhouse gas concentrations, the rate of warming of the Earth's surface has declined somewhat since the 1990s. While it is tempting to find a simple reason for this slowing (or "hiatus") in global surface warming, the climate system is extremely complex and there are many factors which can explain the lumps and bumps in the surface temperature record which also include increases (or "surges") in the rate of warming. The goal of our proposed programme of research is to understand much more fully how all the contributing factors can explain past hiatus and surge (H/S) events and this will ultimately help improve predictions of future climate change over the coming decades and far into the future. The potential causes of H/S events includes: natural (so-called unforced) climate variability, due to complex interplay between the atmosphere, oceans and land; natural climate change due to volcanic eruptions or changes in the brightness of the sun; changes in how heat is moved into the deep oceans due to natural variations or human-caused factors; changes in emissions of gases such as methane due to human activity; limitations in the distribution of temperature observations, such that the hiatus is partly an artefact of imperfect observations. Rather than one single cause it is likely that H/S events are caused by a combination of factors. This is why a large team with a broad range of expertise is required to evaluate the different processes together. Our project, Securing Multidisciplinary UndeRstanding and Prediction of Hiatus and Surge events (SMURPHS) has brought together a comprehensive community of researchers from 9 UK institutes supported by 5 project partners including the Met Office who are experts in the atmosphere, the oceans and the land surface. SMURPHS has 3 broad objectives, achieved through 6 research themes, which exploit theory, observations and detailed computer modelling. Objective 1 is to build a basic framework for interpreting H/S events in terms of energy moving between the atmosphere and ocean and to determine characteristics of and similarities between H/S events. Objective 2 is to understand mechanisms that could trigger H/S events and extend their length, considering both human and natural factors. Objective 3 is to assess whether H/S events can be predicted and what information is needed for near-term prediction of climate over coming decades which is important for how societies adapt to change. To meet these objectives scientists from a range of different disciplines will work on each of these possibilities and communicate their findings across the team. SMURPHS will produce a wide-ranging synthesis of its results. SMURPHS will have many beneficiaries. Beyond the global scientific community, improved understanding of H/S events is important at national and international levels for designing policies to control future greenhouse gas emissions and for effective adaptation to climate change. Intergovernmental Panel on Climate Change (IPCC) assessments have deeply influenced climate policy development at the international and national levels. Scientists involved in SMURPHS have contributed significantly to previous IPCC reports, and SMURPHS science and scientists would contribute significantly to future such assessments.