The COCAS project aims to fill a major void in the global system for observing and studying Climate Change and its Impacts (CC&I) on the world's coasts, and thus meeting the expectations of the Green Pact of Europe in terms of infrastructure for advanced observation and monitoring of the climate / environment (Green Deal, Topic 9.1). It brings together scientists from Europe and so-called “Southern” Atlantic and Mediterranean countries, around the most complete and modern platforms currently existing for long-term and high-precision measurements of key physics parameters. , biogeochemistry and marine biology of coastal areas. These measures are not shared internationally, which delays progress on CC&I measurement and forecasting. The COCAS group will dedicate itself to making its data easily accessible internally and externally, to homogenize the sensors and modernize them, to reinforce internal cohesion and share expertise within the network and with the community and public and private end users . Anchored air-sea buoys, CC&I sentinels in coastal marine regions. Compared to the global ocean, the coastal marine space is more productive, responds more intensely to disturbances, and is in direct contact with human populations. This makes it an essential source of resources and services, changes in which under the effect of CC&I are essential to monitor by key quantity measurements, at the air-sea interface and below the surface. The ANR COCAS network will offer Europe leadership on a new infrastructure, made up of Coastal Anchored Buoys (BACs), existing beyond its borders in the coastal areas of less developed countries neighboring Europe. This will complement the transnational networks of LACs from developed, European (ERI JERICO3) and international deep-sea countries in the Atlantic-Pacific tropics (PIRATA and TAO programs). A European infrastructure to monitor the evolution and impacts of climate change in the southern coastal marine environment in the decades to come. In the southern coastal regions, the lack of reliable data requires a multidisciplinary international mobilization, to describe a “zero” state using reference points, dedicated to oceanic and atmospheric parameters, whose knowledge is key to validate forecasts. local and global climatic conditions and assess the impacts. Nineteen BACs have been deployed “to the South”, by the members of the project (Atlantic, Mediterranean and East Pacific basins). The members of the group have started to work together since the beginning of 2017 and the collective has strong technical and basic and applied research. This is the case not only in environmental sciences and human and social sciences. but also in particular for partnerships with local and international companies, the use of substantial financial and human resources, and the development of links with the local industrial and institutional fabric, allowing the dissemination of information to governments and the public about Coastal CC&I. Three structuring objectives. The members of the 16 countries (4 European, 11 in the South and the USA) of the project are committed to working on the three pillars of an EU Infrastructure network: coordination and sharing of expertise internally as well as with the rest of the community, standardization and innovations for quality platforms and data, and easy access for internal and external users. Partnerships are established (see scientific committee) for the integration into the landscape of existing ERIs. To achieve this, the work will consist of animations such as webinars, annual meetings, and bi-monthly videoconferences aimed at creating a common database and coordinating the drafting of the EU Infrastructure project.

Coastal ecosystems functioning is exposed to many alterations associated with global change. In order to achieve sustainable resource management, it is necessary to better understand the species’ response facing environmental variability. In the Sine-Saloum Delta (Senegal), the bloody cockle (Senilia senilis) is a key bivalve species for the women's communities that exploit them, themselves key to the socio-ecosystem of the Delta. However, given our current knowledge, it is impossible to predict the response of this species to changes in its environment in a context of global change. Very little information on the biology of this species is available. The IROCWA project therefore aims to characterize the biological response of the bloody cockle to a wide range of past and present bioclimatic conditions. This will provide knowledge and tools to help predict the future consequences of climate change on this key species in West Africa. This project develops an innovative interdisciplinary and integrated approach, combining experimental ecophysiology, bioenergetics modelling, paleoecology and paleoclimatology. Expected results will: (i) delimit the ecological niche of the species (ii) describe the variability of individual growth over recent centuries in relation to contrasting precipitation patterns and (iii) develop a mechanistic model simulating the effect of environmental variability on individual life-history traits. IROCWA will combine in-situ observations, laboratory and in-situ experiments and modelling approaches. IROCWA is organized in three scientific work packages (WP), with a high level of interaction between them. WP1 will combine sclerochronology and sclerochemistry to reconstruct past growth patterns and environmental conditions, from AD 800 to present days. WP2 will develop the first ecophysiological experiments ever done to quantify the S. senilis optimum and tolerance range regarding biotic and abiotic environmental variables (temperature, salinity, oxygen, food). Finally, WP3 will calibrate the first bioenergetics model for S. senilis following the Dynamic Energy Budget (DEB) theory, including a biogenic carbonate module, allowing to both (i) simulate the full life-cycle growth of S. senilis (shell, soft tissues and reproductive outputs) under varying environmental conditions and (ii) reconstruct food conditions from historical shells. Reconstructing the environmental conditions encountered by S. senilis on a scale of several centuries provides an unprecedented experimental context for monitoring the biological response of a bivalve species to aridification phenomenon which is one of the largest environmental change observed on earth. This historical record, in the light of quantitative paleoclimate, experimental ecophysiology and bioenergetics modelling, will yield a comprehensive and mechanistic understanding of the biological sensitivity of this species to environmental change, allowing projections of this economical resource at the population scale. Such evidence-based information is key to support a sustainable development of artisanal fisheries. Furthermore, S. senilis is a model species to validate the innovative approach developed in IROCWA for future bioclimatic studies with other species and/or in other ecosystems. This is particularly timely as coastal vulnerability in face of global change is a major concern worldwide.

The El Niño Southern Oscillation (ENSO) is the leading mode of interannual climate variability on earth. It consists of irregular, alternating phases of warm (El Niño) or cold (La Niña) Sea Surface Temperature (SST) anomalies in the tropical Pacific Ocean, but has global climate impacts through atmospheric teleconnections. It is predictable 2-3 seasons in advance, so ENSO is also a major source of global seasonal climate predictability. State-of-the-art ENSO forecasts however have not performed well for “extreme” El Niño events such as those in 1982-83, 1997-98 or 2015-2016. With climate projections suggesting that such extreme events may become more frequent, it is vital to improve our understanding of the processes involved in these ENSO events. ENSO grows through the Bjerknes feedback, a positive feedback loop between the ocean and the atmosphere. In this feedback loop, an SST anomaly induces deep atmospheric convection. The resulting changes in surface wind drive an ocean response that strengthens the initial SST anomaly, allowing ENSO events to grow. While the oceanic component of this feedback loop is well understood, there are far fewer studies of its atmospheric component. Yet, the atmospheric component of the Bjerknes feedback exhibits strong non-linearities which have been recently suggested to play a key role in extreme El Niño events. Deep convection indeed only occurs for SSTs above ~27.5°C, implying that the atmosphere will be more responsive to SST fluctuations in the warm western Pacific than in the colder eastern Pacific. The conceptual models used to understand ENSO do not account for this non-linearity, or for other potentially-important sources of atmospheric non-linearities such as heat flux feedbacks. Additionally, the capacity of Coupled General Circulation models (CGCMs) used for ENSO research and forecasting to reproduce the non-linear atmospheric response to ENSO SST anomalies has not been systematically evaluated so far. Previous work suggests that this non-linearity likely plays a key role in linking the models’ systematic biases to their documented underestimation of the Bjerknes feedback. Developing tools to quantify, understand and model the non-linear wind response to ENSO SST anomalies is thus a vital prerequisite to a) understanding extreme El Niño mechanisms and b) being able to diagnose the source of ENSO biases in CGCMs. ARiSE proposes to use observational analyses and a hierarchy of atmospheric and coupled models (from conceptual to general circulation models) to better describe the non-linear atmospheric response to ENSO and its impact on ENSO properties, and in particular extreme El Niño events. In Work Package (WP) 1, we will use observations and two types of atmospheric GCMs to produce a seasonally-dependent transfer function between SST and wind stress variations, and explore its non-linearity. In WP2, we will develop the simplest possible atmospheric model that encapsulates essential dynamical and thermodynamical non-linearities for ENSO, and investigate their impact on ENSO, in an intermediate and a conceptual model. In WP3, we will use the results from the previous WPs to improve our understanding of ENSO in CGCMS: a) we will diagnose the specific mechanisms of extreme El Niños in a CGCM; b) we will evaluate links between atmospheric non-linearities and ENSO biases in the CMIP database. This will provide tools for improving ENSO representation in state-of-the-art CGCMs used in forecast mode. The current project gathers a unique blend of oceanographers and atmospheric scientists with good expertise in ENSO, including developers of some models used in the project. This project also benefits from the support of several renowned international collaborators on their own funds. ARiSE is a unique opportunity to make a step change in our understanding of tropical air-sea interactions, the role of the atmosphere in extreme El Niños with potentially large societal impacts.

Over a large part of Antarctica, the surface mass balance (SMB) is controlled by a few extreme events, resulting in a high natural variability of this parameter. In particular, extreme moisture intrusions linked to Southern Ocean Atmospheric Rivers (ARs) have been recently demonstrated to be major sources of both snow accumulation, heating and surface melt. Despite their key role, there is a general omission of AR variability, and more broadly of extreme events, in studies of past and future Antarctic climate and SMB. ARCA will assess the impact of ARs on the surface mass balance of Antarctica and will explore to what extent past AR activity can be recorded in ice cores. To reach this goal, ARCA is organized in 4 working packages. 1) ARCA will use recent novel numerical methodologies for identifying ARs applied to global and regional circulation models (GCMs and RCMs respectively). New algorithms will be applied to historical, present and future climate simulations. 2) ARCA will provide new field measurements of water stable isotopes and chemistry composition of snow precipitation and air masses from Adelie and Wilkes Lands, and 3) apply a regional scale modeling of water stable isotopes to interpret the signal observed in the field. 4) ARCA will finally revisit data from existing ice cores (aerosol content, e.g. sea salt, insoluble particles, water isotopes). Following this methodology, ARCA proposes to: 1) understand how natural variability and external forcings control the AR activity. 2) quantify AR moisture and heat transport towards Antarctica and their impacts on the SMB of Antarctica. 3) describe AR impact on the isotopic and aerosol contents of air masses transported through East Antarctica, 4) analyze the processes (e.g., moisture origin, sublimation of hydrometeors) producing characteristic signals in air masses during ARs, 5) estimate the induced bias in ice core records in regards to past temperature reconstructions. 6) Evaluate (qualitatively) past AR variability and the resulting bias in current estimates of past millenium climate in Antarctica. The ARCA project will deliver products that describe AR climatology and variability (occurrence maps, statistics), their atmospheric moisture signature (time-series of isotopes and aerosol content), and their impacts on Antarctic climate and SMB (through maps of induced melting and accumulation). Results will be presented for the 20th and 21st centuries, aiming in particular at projecting observationally constrained impacts of ARs on the SMB. ARCA will define a multi proxy approach to define how past AR could be retrieved in ice cores and provide a metric using water isotopic composition in ice cores to qualitatively define periods of higher and lower AR activity over the past millennium. Finally, ARCA will define the regions of Adelie and Wilkes Lands where ice cores should be drilled to best capture the AR and their influence in past climate variability. The ARCA consortium presents recognized experts from the IGE, LSCE and LOCEAN in particular in atmospheric modeling with polar-Regional Circulation Models and General Circulation Models, AR detection and estimation surface mass balance for Antarctica. The project will also rely on the broad expertise of the group in the interpretation of water isotopes and aerosol contents in air samples and ice cores.