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Sessions overview

Day 1

Session 1 – Introduction and Scene Setting

This session aims at introducing the current state of the art in carbon cycle research form the perspective of Space Agencies, funding organisations and carbon research initiatives. It will include review of progress against the recommendations of the 3rd Carbon from Space, consider the latest synthesis of IPCC and its observations on understanding of the terrestrial carbon cycle and briefly introduce a series of opportunities that the carbon cycle community could take advantage of, in particular, upcoming satellite missions, new initiatives and new structures to improve the interface between the space, in situ and model communities. This session provides the context for the subsequent discussion sessions, whose scope is then to provide specific recommendations for research and application activities over the next 5 years.

Session 2 – Opportunities with new data

The objective here is to report on the new opportunities arising now and in the future in space but also in situ covering all the planning for new missions with relevance for the terrestrial carbon cycle.

The intention is to identify gaps and opportunities across missions and in situ network efforts and hence to establish mechanisms, experiments, collaborations, data platforms, model interfaces to make best use of these new observations. This will include identifying potential programme opportunities e.g. the proposed ESA Sentinel User Preparation (SUP) programme.

The sessions will include the status of missions of relevance for the terrestrial carbon cycle e.g. BIOMASS, FLEX, NISAR, GEDI, SAOCOM, ECOSTRESS, Sentinels and Sentinel Expansion and in situ network efforts e.g. NEON, TERN, ICOS, FOS, AbOVE.

Opportunities for scientific exploitation of commercial missions will also be covered e.g. Planet, Pleiades, WorldView, COSMO-SkyMed, PRISMA etc

Session 3 – Model-Data interfaces – what are the gaps and opportunities

The objective of this session is to assess the current provision of data, both in situ and space-based and its use in constraining/informing models. This includes specifically assessment of the consistency of models at multiple scales, the appropriateness and accuracy of process representation in models in relation to observations also at multiple space and temporal scales.

The intention here is to look for opportunities to:

  • improve models such that they are consistent across spatial scale or that the differences between model formulations are well characterised.
  • identify missing processes that are needed to improvement model-data consistency and establish schemes to address these
  • improve the consistency in processing approaches/assumptions used in models and in observations such that they can be compared more appropriately.
  • Improve the consistency in derivation of parameters from observations such that they are also more consistent and appropriate for use as constraints and for verification of model behaviour.
  • reduce the discrepancies between model formulations such that models driven bottom-up and those constrained top-down are reconciled.
Community Session 1: Synergistic use of complementary observations for constraining the carbon cycle across scales

This session is aimed at demonstrating the synergistic exploitation of Earth Observation data from space together with in-situ observations in a consistent modelling framework. It addresses progress and results from ESA’s Land Surface Carbon Constellation (LCC) project but is open to additional community contributions. The emphasis is on the integrative view on the terrestrial carbon cycle bringing together modelling and observations in a data assimilation framework. The session links to the existing sessions on new data (Session 2), model-data interfaces (Session 4) and assessments for the GST (Session 8). The main objectives are to highlight the synergistic use of data and models as well as identify potential gaps in both observations, model processes as well as observation operators that link the model state to the observations.

The session covers the following aspects and objectives:

  • integrated approach to the carbon cycle exploiting both observations and modelling
  • development and validation of dedicated observation operators guided by campaign observations
  • systematic assessment of uncertainties in models and observations
  • consistent assimilation of complementary EO data (among observations but also with the underlying model assumptions)
  • synergistic exploitation of satellite observations (focusing on, but not limited to Earth Explorers BIOMASS, FLEX, SMOS)
  • improved understanding of the terrestrial carbon, water and energy cycles
  • improved process understanding and uncertainty reduction in modelled fluxes
  • identification of gaps in
    • in-situ & satellite observations (resolution, coverage, revisit time, variables)
    • observation operators
    • model processes

Day 2

Session 4 – Land use change and agriculture impacts on the carbon cycle

The need for improved knowledge of and representation of anthropogenic impacts on the terrestrial carbon cycle is fundamental as these have strong regional variability and represent the mechanisms by which interventions can be made to move towards net-zero carbon balance. In both in agriculture and forestry there is a need to gain a better constraint on emissions and their biophysical and biogeochemical consequences (as agriculture, forestry and other land uses (AFOLU) contribute around 23% of total global anthropogenic GHG emissions). However, such an estimate is accompanied by significant uncertainty, which becomes even more important for non-Annex-I countries where AFOLU emissions represent a large portion of many developing countries’ total emissions (Tubiello et al., 2015 [1], Perugini et al. 2021 [2]).

How can we capitalise on the latest satellite observations especially at high spatial resolution and repetition to advance the understanding and quantification of the land use related carbon pools and fluxes with special focus on agricultural practices and land use changes?

[1] Tubiello, F.N., et al., 2015. The Contribution of Agriculture, Forestry and other Land Use activities to Global Warming, 1990-2012: Not as high as in the past. Glob. Change Biol. Bioenergy 21 (7), 2655–2660.

[2] Perugini, L., et al. 2021, Emerging reporting and verification needs under the Paris Agreement: How can the research community effectively contribute? Environmental Science and Policy,122, 116–126, https://doi.org/10.1016/j.envsci.2021.04.012

Session 5 – Forests and the Glasgow Leaders’ Declaration

We, the leaders of the countries:
Emphasise the critical and interdependent roles of forests of all types … to help achieve a balance between anthropogenic greenhouse gas emissions and removal by sinks. We therefore commit to working collectively to halt and reverse forest loss and land degradation by 2030 while delivering sustainable development and promoting an inclusive rural transformation.

We will strengthen our shared efforts to conserve forests and other terrestrial ecosystems and accelerate their restoration [whilst] facilitating trade and development policies, internationally and domestically … that do not drive deforestation and land degradation. We will facilitate the alignment of financial flows … to reverse forest loss and degradation, [and] accelerate the transition to an economy that is resilient and advances forest, sustainable land use, biodiversity and climate goals.

This requires answers to the following questions:

  • Is the net balance in forest area positive or negative at global and regional scales? (are we planting more trees than we are losing?)
  • Are planting schemes consistent and maintained over time (do new trees get to be mature?)
  • Are the selected species appropriate for carbon sequestration and are they being planted in the right place from a carbon perspective?
  • Are the management approaches in place to ensure carbon remains in place long term (are they fast- or slow-growing? How long do they live and what happens when they die?
Session 6 – Carbon in the Arctic

In a warming Arctic, longer and warmer growing seasons may accelerate the microbial breakdown of soil organic carbon stored beneath and within permafrost increasing the magnitude and timing of CO2 and CH4 release to the atmosphere. In addition, rapid permafrost thaw may occur throughout the Arctic, altering surface hydrology, which may contribute to further thawing. Due to these localized feedbacks, permafrost degradation may occur at a much faster rate than would be predicted from changes in air temperature alone. This may lead to a potentially irreversible acceleration in the methane emissions that may have a significant impact on the climate system. However, there is a critical need to quantify:

  • current methane emissions in the Arctic and what their sources and sinks are
  • whether the fraction of the carbon permafrost feedback will increase in the future
  • why rapid changes in permafrost are not always followed by a commensurate net rise in methane emissions

Addressing those questions requires to overcome major scientific and technical difficulties associated to the scarcity of observations, the complexity of satellite retrievals, the discrepancies between bottom-up and top-down approaches, the understanding of complex processes and its transfer to advanced models.

Community Session 2: Methane in the Arctic

The Arctic accounts for half of the organic carbon stored in soils. There is high confidence that the thaw of terrestrial permafrost will lead to carbon release, but only low confidence regarding timing, magnitude and relative role of CO2 versus CH4 according to the sixth assessment report of IPCC (2021). There is a general consensus that these issues can be tackled through support by satellite observations, but this has not been fully exploited to date. The recently inaugurated NASA/ESA Arctic Methane and Permafrost Challenge (AMPAC) strives to address these questions inter alia through making use of synergistic measurements, activities to improve satellite retrievals with a clear focus on high latitudes and promoting new dedicated satellite sensors as well as improving validation of existing and upcoming satellite missions.

The aim of the community session is to review the availability of data with respect to methane and identify gaps. This includes data from space as well as airborne campaigns and in situ measurements needed for validation, up-scaling and preparation of future missions. Subtopic of ‘Carbon in the Arctic’, contribution to ESA/NASA AMPAC initiative.

Day 3

Session 7 – Global-regional-national assessments for the global stocktake

Global Stocktakes (GSTs) are conducted at five-year intervals, to periodically take stock of the implementation of the Paris Agreement to assess collective progress towards achieving its purpose and long-term goals starting in 2023. The outcome of each GST is then used to enhance the collective ambition towards achieving the long-term goals of the Agreement and strengthen international cooperation for climate action.

  • How do we refine of knowledge of the terrestrial carbon source and sink terms at the resolution of nations and below?
  • How can information produced globally be made consistent with national needs and reporting obligations?

To improve the predictive capabilities, Earth System models must use schemes able to properly ingest all the new information coming from EO data, and new variables in ground networks, to fully exploit the available information and to address the most critical aspects of the carbon science which are difficult to constrain from direct observations.

In turn there is a need to provide the data more appropriately for their use in constraining/verifying model behaviour and improving the consistency in approaches for estimation of key model variables such that differences in relation to spatial and temporal scale of the observations (from space and in situ) are understood better, these differences are reduced where possible and uncertainties in data products are characterised fully in the product in a manner that is transparent and traceable.

Session 8 – Extremes, disturbance and vegetation response

Terrestrial ecosystems and their functioning are strongly coupled with climate and can be disrupted by both slow and abrupt change in climate and nutrient/water availability. Extreme weather events of variable duration may trigger feedback responses that disrupt this coupling especially when these are reinforced by other disturbing factors, both natural and anthropogenic, e.g. change in ecosystem structure, resource depletion, drought and impacts of wind, fire, pests etc. Ecosystems have the potential to be susceptible to the combination of such stressors, however, the majority of research on ecosystem functioning does not account for such combinations nor their duration and timing.
There is therefore a need to assess to what extent space-based observations, combined with in situ monitoring and models:

  • can identify and characterise the responses of ecosystems to both long and short-term stress (slow change in climate, weather extremes, disturbance etc)
  • can characterise change in ecosystems in relation to their role in the carbon cycle, in particular, change in behaviour from sinks to sources.

The discussion will focus on the needs for new observations, experiments and model development taking advantage of recent extreme events (drought, major disturbance, slow degradation) and/or identified anomalous/slow change in climate.

Session 9 – Terrestrial Carbon in a Digital Twin Earth

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Community Session 3: Observing Carbon-climate Feedbacks from Space: Prospects and Challenges

Critical to successful mitigation of climate change is quantifying the relationship between carbon emissions and concentrations, which
are mediated by the natural carbon cycle. Over the last decade, substantial stress has been placed on the carbon cycle from severe
climate anomalies exacerbated by land-use change in critical zones such as the Amazon. Rapid changes to the carbon cycle raise the
specter of carbon-climate feedbacks, which directly alter the net atmospheric greenhouse gas concentrations and could compromise
climate targets. Space-based observations have the potential to play a crucial role in quantifying these feedbacks and how they could
impact policy deliberations. This session solicits research on carbon-climate feedbacks from a space-borne perspective including new
techniques to quantify feedbacks, improved observations and understanding of processes governing feedbacks, and observational
constraints on carbon-climate projections.

Day 4

Session 10 – Recommendations/Next Steps

Each of the sessions will conclude with a series of recommendations which will be brought together in this session for wider discussion. The intention here is to use these to guide the development of the Carbon Agenda 2023-2028. This will focus on the science side but with a view also to making the scientific contribution more compatible with the needs of, for example, the Paris Agreement, the Global Stocktake and the Glasgow leaders’ declaration on land use and forestry.

Recommendations are sought also on how to take best advantage of the existing and upcoming satellite missions including specific actions on model improvement and in situ observations that are vital to support such work.

Finally, the opportunities for experiments and collaboration will be discussed in terms of funding possibilities e.g. the ESA-EC RTD Earth System Science Initiative and meeting opportunities e.g. 11th International Carbon Dioxide Conference (ICDC11).