A comprehensive assessment and quantification of the role of terrestrial biogeochemical dynamics and the role of vegetation in the carbon cycle, compared to the pre-industrialisation situation, building on dedicated in situ data collection, novel satellite data development, and advanced carbon cycle modelling.

Project results are expected to contribute to all of the following outcomes:

• Enhanced understanding and characterisation of the terrestrial carbon pools and fluxes, including through taking account of hydrological exchanges, with unprecedented accuracies and spatial scales, building on the advent of a new generation of satellite missions (e.g., ESA’s BIOMASS, FLEX, Sentinel missions, NASA’s NISAR, GEDI, ICESat-2 etc…), that radically change the way the terrestrial carbon cycle can be observed.
• Improved methods for the monitoring of key ecosystems state in Europe, regarding terrestrial carbon, including e.g. forestry, croplands, peatlands, inland water, extensive grasslands, tundra, tidal marshes, seagrass, and mangroves, and tackling key gaps in observations, e.g. age-structure, species richness, canopy structure (including use of Terrestrial Laser Scanning), observations of wood density, interaction with hydrology and exchange with the atmosphere in particular observations of biological volatile organic compounds, CO2, CH4, N2O, and black carbon/particulates emissions.
• Improved handling of anthropogenic management practices (land use including forestry) in terrestrial carbon modelling, including lateral transfers of carbon (notably in the form of harvested biomass including exports, imports, and use as well of land-water exchange).
• Improved understanding of impacts on the carbon cycle of extreme events (wind throw, drought, pest outbreaks, fire), and of the impacts of anthropogenic disturbance including degradation and behaviour and recovery of forest post-disturbance.
• Improved consistency between top-down methods such as atmospheric inversions and bottom-up approaches based on land-surface models, in-situ and satellite observation, flux measurements, and national and global statistics.
• Assessment of the consistency of observation and advanced models through benchmarking activities at multiple scales including point measurements, and satellite observations at multiple temporal and spatial resolutions.
• Novel monitoring frameworks combining remote and proximate sensing techniques with machine learning and edge computing.

The main challenge of this topic is to develop an enhanced capacity to better characterise and reduce uncertainties of the carbon cycle related to key terrestrial European ecosystems as a function of anthropogenic emissions, environmental forcing conditions, and management practices. In order for this challenge to be met, actions should be performed at spatial resolutions required to represent the mechanisms by which human interventions necessary to move towards net-zero carbon balance, can be quantified. Further, the dynamics and response of vegetation to climate change, short- and long-term stress, natural dynamics (e.g. fire), and especially change in frequency, form and severity of extreme events, need to be better understood and quantified.

Proposals should address the above challenges through:

• Coordinated European effort to expand dedicated campaigns to collect in situ-data, including from citizen observations, on land cover, land use and related changes, and on the main processes caused by these, to support the modelling of these changes based on current and historical trends, and to develop empirically based scenarios connecting land use and land cover change to carbon emissions, and sequestration potential.
• Advances in land surface and carbon modelling supported by high-performance computing capacity, allowing models to be run at unprecedented resolutions, and accuracy, through improved data assimilation workflow from remotely sensed data and vegetation models. The emphasis should be on area wide effect of the ecosystem’s microbiome, and consistency across spatial and temporal resolution and with satellite observation processes.
• Extending and complementing satellite observations with elements linked to the LUCAS survey of Eurostat, to the EU Soil Observatory (EUSO) initiatives on integrated soil monitoring systems, and to research infrastructure e.g. eLTER and ICOS, as well as through comparison with past data and through coordination with Earth observation efforts (spectral signature characterisation, biophysical and biogeochemical observations commensurate with satellite resolutions, aircraft / unmanned aerial vehicle campaigns).
• Specific efforts to develop carbon and land surface models consistent with specific variables or outputs that can be directly interfaced or compared with satellite observations e.g. above ground biomass, soil moisture, solar induced fluorescence, disturbance dynamics e.g. fire, and inclusion of additional key processes (coupling with Nitrogen and Phosphorus cycles and water, CO₂ fertilisation, assimilation of photosynthesis rates from global observation for direct gross primary production estimation).
• A significant coordination effort and collaboration with the relevant activities of major international scientific groups (e.g., IPCC, Global Carbon Project), the Copernicus Atmosphere Monitoring Service and the ESA Carbon Science Cluster^[1].

This topic is part of a coordination initiative between the European Space Agency (ESA) and the EC on Earth System Science. Under the EC-ESA Earth System Science Initiative, both institutions aim at coordinating efforts to support complementary collaborative projects, funded on the EC side through Horizon Europe, and on the ESA side through the ESA FutureEO programme as part of the ESA Carbon Science Cluster.

Proposals should address the collaboration with ongoing or future ESA projects, including those that will be funded through dedicated coordinated invitations to tender, and should towards this end include sufficient means and resources for effective coordination.

Applicants should ensure coordination with complementary projects funded under the ESA Carbon Science Cluster of the FutureEO programme including relevant ESA activities related to the use of the novel BIOMASS^[2] and FLEX^[3] missions and potentially the Copernicus CO₂M^[4] mission in the future.

[1] https://eo4society.esa.int/communities/scientists/esa-carbon-science-cluster/

[2] https://earth.esa.int/eogateway/missions/biomass

[3] https://earth.esa.int/eogateway/missions/flex

[4] https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Copernicus_Sentinel_Expansion_missionshttps://www.eumetsat.int/copernicus-co2m-science-support