In addition to urgently needed emission reductions, the IPCC Special Report on Global Warming of 1.5°C highlighted with high confidence that all projected pathways that limit warming to 1.5°C also require the use of Negative Emission Technologies (NETs). The majority of NETs research has focused on land-based methods, however, meeting climate mitigation targets with land-based NETs alone, will be extremely difficult, if not impossible. NET knowledge on the ocean-based counterpart, which has a considerably higher capacity to store carbon, remains limited. OceanNETs will investigate the feasibility and impacts of emerging ocean-based NETs through a transdisciplinary research approach. We will establish if ocean-based NETs can play a substantial and sustainable role in medium-to-long term pathways that achieve climate neutrality from the perspective of reaching the Paris Agreement goals. The impacts of ocean-based NETs on society and the Earth system will also be determined. The respective policy challenges, as well as the implications of interactions between ocean- and terrestrial-based NETs in these pathways, will also be assessed. Analyses will account for both risks and co-benefits, as well as any feedbacks these may have on NET efficacy and feasibility. The project will contribute to major international, national, and EU assessments of possible climate mitigation options. OceanNETs breaks new ground by bringing together recognized NET experts from economic, political, legal, social, and natural sciences and establishing a tight dialogue with stakeholders in a single integrated project. The scientific experts will synergistically work in parallel and together, whilst interacting with stakeholders, to evaluate ocean-based NETs within a UN sustainable development goals framework. The strength of OceanNETs lies in its transdisciplinary approach as opposed to existing disciplinary studies.

OCEAN:ICE will assess the impacts of key Antarctic Ice Sheet and Southern Ocean processes on Planet Earth, via their influence on sea level rise, deep water formation, ocean circulation and climate. An innovative and ambitious combination of observations and numerical models, including coupled ice sheet-climate model development, will be used to improve predictions of how changes in the Antarctic and Greenland ice sheets impact global climate. It will make new circumpolar and Atlantic observations in observational gaps. It will assimilate these and existing data into improved ice sheet boundary conditions and forcing, producing new estimates of ice sheet melt and impacts on ocean circulation, including the Atlantic Meridional Overturning circulation. It will develop, calibrate and assess models used to predict the future evolution of the giant ice sheets. It will reduce the deep uncertainty in the impact of their melt on societally relevant environmental changes on decadal to multi-centennial time scales. OCEAN:ICE will assess the potential for passing ice sheet 'tipping points' and their consequences for ocean circulation and climate. OCEAN:ICE will raise the profile of European research through its extensive network of international collaborators, who provide scientific and logistical support. It will directly contribute to the All-Atlantic Ocean Research Alliance through observations, logistical collaboration and analysis. It will significantly advance the state-of-the-art in coupled ice sheet-climate modelling and directly contribute to international climate assessments such as the Intergovernmental Panel on Climate Change and World Ocean Assessment. It will link organically to European data centres to disseminate its data, following FAIR and INSPIRE principles. It will deliver improved assessments of European climate impacts from the melting ice sheets, with actionable risk and timescales, to policymakers and the public.

The ocean is key in the global C cycle, taking up ca. 25% of the CO2 we emit, slowing climate change and giving us more time to mitigate and adapt to climate change. The Ocean C Value Chain (VC) of observations, data QC & analysis delivers key information around this to decision makers such as the Conference of the Parties. The RIs play a pivotal role in the VC via their ability to operate at scale & pool resources to ensure common data standards and operational practices. The urgency of the climate crisis drives us to put this VC on a much more robust footing with the World Meteorological Organisation leading the planning of a Global Greenhouse Gas Watch (G3W) covering all components of the Earth System. Unfortunately the VC currently delivers estimates of Ocean C uptake much larger than those from models, leading to a damaged ability to manage climate change. However further work suggests that observations at a much higher density in the Southern Ocean (SO) would substantially resolve this issue. Our ability to deliver these via ships is limited by the small number that enter the SO and we therefore need many more observations from research vessels, citizen science platforms, autonomous robotic floats & surface platforms. This step change requires substantial technological innovation and complex data synthesis. TRICUSO will address these needs by a) improving the sensing technologies on floats and small uncrewed surface vessels, b) supporting citizen science on yachts and potentially cruise and expedition vessels, c) integrating biological observations into the work flow, d) improving data flows to scientists, e) evaluating the density of observations needed & f) proposing fit for purpose governance structures that allow the RIs to operate within the G3W. These actions will enable us to have a much firmer grip of how and why Ocean Carbon uptake varies and thus a much firmer evidence base on which to make decisions around managing climate change impacts.

AQUACOSM-plus advances European mesocosm-based aquatic RI by integrating the leading mesocosm infrastructures into a coherent, interdisciplinary, and interoperable network covering all ecoregions of Europe. AQUACOSM-plus widens the user base by extending TA provision (> 13000 person-days), and strengthening the offered services, with 10 new partners, including a NGO and doubling of SMEs. We initiate actions to increase competence in mesocosm science in new EU member states (Hungary and Romania), and emphasize training of young scientists through summer schools covering various disciplines including effective science communication. AQUACOSM-plus develops near-real-time Open Data flows and improved metadata, thus promoting Open Mesocosm Science in collaboration with leading EU-supported initiatives in the EOSC and fosters wider sharing of information, knowledge, and technologies across fields and between academia, industry, and policy makers/advisers. AQUACOSM-plus develops new technological capabilities for mesocosm research, to effectively execute scenario-testing for Climate Change -related pressures on aquatic systems from upstream fresh waters to the sea. These developments include mobile large-scale mesocosm approaches, leading-edge imaging technologies, and affordable methods to obtain high-frequency data on community change and greenhouse gas fluxes in mesocosm settings. AQUACOSM-plus will progress beyond current achievements by actively pursuing RI-RI collaboration with European environmental RIs (LTER, ICOS, DANUBIUS, JERICO) at all project activity levels (NA, JRA, TA). Multidisciplinary joint research, combining observational data and modelling approaches with targeted mesocosm experiments, is a key step towards successfully tackling current and future Grand Challenges. This involves shared capacity building via symposia, expert summits, and open workshops, with the aim of co-designing future aquatic research actions and their RI demands.