Themes at ICOS Science Conference 2020

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The overall, overarching theme of the 4th ICOS Science Conference is "Knowledge for shaping the future – understanding the Earth's biogeochemical processes”.

The conference is structured around following 8 themes:

Subtheme 1: Learning from extremes – integrating measurements and modelling for process understanding

Conveners: Ana Bastos, Wouter Peters, Philippe Ciais

The frequency and intensity of climate extremes has been made more likely by anthropogenic climate change. Over the past decades, record-breaking droughts, heatwaves or heavy floods have been registered, with severe impacts on societies, economies and ecosystems. Understanding how climate extremes affect ecosystem water, carbon and energy cycling, and how resilient different ecosystems are to these events is fundamental to anticipate future impacts on ecosystems’ functioning and the services they provide to societies. A more comprehensive understanding of these impacts is now possible due to well established in-situ observation networks, remote-sensing products and the improvement of process-based modelling.

This session seeks contributions focusing on the impacts of recent extreme events on the diverse ecosystem processes, as well as on the long-term mortality and post-disturbance recovery trajectories. The analysis of compound events (e.g. drought and heat) and of cascading impacts (e.g. storms and insect outbreaks) is of particular interest to this session. The session will cover contributions from in-situ, remote-sensing and modelling approaches, with a special focus on integrative approaches.

Subtheme 2: Emerging mechanisms of ecosystem functioning in a warmer and drier world

Conveners: Jose Gruenzweig, Ana Rey, Anders Lindroth (TBC)

Over the past decades, we have gained much knowledge on how ecosystems respond to a warmer and drier climate that often involves extreme heat and drought events. These responses concern processes of ecosystem functioning that are conventionally studied in most biomes. However, responses to climate change may include an unprecedented shift from commonly studied mechanisms of ecosystem functioning to a set of mechanisms that are prevalent in drylands, but are ‘novel’ to most other climatic zones. We envision that with continued climate change, mechanisms and drivers that commonly control ecosystem functioning in drylands become widespread in non-xeric regions of the world. These ‘dryland mechanisms’ include landscape-scale processes, such as horizontal resource redistribution, self-organization of vegetation patterns and decoupling of biogeochemical cycles.

Ecosystem-scale processes include drying-wetting cycles of soils leading to pulses of biological activity, hydraulic redistribution of water in soils by roots, and biotic processes enhanced by non-rainfall water sources, such as dew. Extreme heat induces trace gas emissions and thermal degradation of organic matter, while intense solar radiation degrades surface organic materials by photochemical processes. With many climatic zones experiencing more pronounced warm and dry weather, it is critical to include these ‘novel’ mechanisms to better understand and predict global ecosystem responses to future climate conditions.

The drought that hit Europe during 2018 had profound effects on some ecosystems with carbon balances turning from strong sinks to neutrality. Situations like this are extremely valuable for testing and developing ecosystem models to be used in climate models. Also the recovery after a severe drought is important to understand.

This session welcomes papers related to the 2018 drought, more general effects on evaporation and energy fluxes as well as on how ecosystems respond to a warmer and drier climate.

Conveners: Leena Järvi, Andreas Christen, Kevin Gurney

•    Novel urban monitoring networks and platforms
•    Micrometeorological measurements of local-scale emissions and sinks
•    Emission inventories including emission and uptake hotspots
•    Atmospheric observations of urban greenhouse gas plumes
•    Uncertainties in urban greenhouse gas budgets obtained with different methods

Urban areas are major contributor to total anthropogenic greenhouse gas (GHG) emissions. Understanding in detail the total emissions of urban GHGs, their temporal and spatial distributions, including sinks, is a key for reducing emissions and identifying effective emissions reduction strategies. Urban observations, modelling, and spatiotemporally-explicit bottom-up estimation of GHG emissions can enable an independent evaluation for self-reported emission inventories. Different approaches for the urban GHG emission estimation exist - ranging from micrometeorological emission measurements and isotope analyses to urban scale concentration monitoring and modelling. Novel city-wide measurement platforms including mobile observations and advanced high-resolution bottom-up flux estimation are emerging. At the same time, advances in ground-based and satellite remote sensing allow for complementary estimation for urban greenhouse gas emissions.

This session will bring together the different methodologies used to examine and understand urban greenhouse gas budgets, their emissions and sinks, and dependencies on different environmental factors at different scales. We further welcome contributions that showcase how urban GHG estimation can be integrated in networks, such as WMO IG3IS.We welcome contributions based on conceptual, experimental, observational or modelling approaches.

Conveners: Daniel Mayor, Richard Sanders, Stacey Felgate, Chris Evans, Zhiliang Zhu, Lisamarie Windham-Myers, Peng Gong, Gyami Shrestha, Richard Sanders, Michele Giani, Agneta Fransson and Vassilis Kitidis, Meike Becker, Thanos Gkritzalis

The interfaces of land, water and atmosphere are a critical research and monitoring priority of carbon and other greenhouse gas (GHG) fluxes:
i)    Wetland ecosystems store significant pools of carbon, and significantly influence global carbon budgets via emissions of CO2 and methane.
ii)    The flow of terrigenous organic matter (tOM), sediments and dissolved carbon across the land-ocean aquatic continuum is a significant and increasing component of the global C cycle
iii)    Shelf seas play key roles in the global C cycle and the ocean carbon sink via the continental shelf pump which absorbs CO2 at the surface and transfers it to deep water
Measuring and accounting for these fluxes in these systems and understanding what controls them across different scales in space and time is challenging due to their high variability, poor representation in maps and models and the relatively small number of high accuracy observations.

In this theme we plan several sessions to bring together researchers from different fields in order to investigate the similarities, differences and links in our studies.

We invite studies (observational (remote sensing and fieldwork), experimental, theoretical and technological perspectives) focusing on:
•    Coastal tidal wetlands and nontidal inland freshwater wetlands
•    Quantifying and understanding land-ocean tOM fluxes
•    The role of estuarine environments in the ocean carbon sink and how they are responding to resource exploitation and climate change
•    Constraining fluxes at the marine boundary layer and the associated uncertainties

When designing and implementing the ICOS Research Infrastructure and its observational networks, a huge effort has been put into measurement precision, compatibility and accuracy. Here we aim at evaluating and discussing the success of this effort, concerning, on one hand, the measurements themselves and their representativeness but also their value for our ability to quantify European and global GHGs fluxes and budgets.
The main question to be addressed in this topic is how well ICOS RI and its users have proceeded in the aim to better understand the driving processes of GHGs exchange, to enable future projections and to provide input for supporting the Paris agreement e.g. by supporting monitoring and verification as well as future Global Stocktake efforts. 
The theme invites presentations assessing our current measurement uncertainties and their quantification, the completeness and representativeness of the existing networks, and finally the integration of bottom‐up versus top‐down flux estimates. Furthermore, it will focus on some detailed questions:

Subtheme 1: Laser scanning technologies for innovative forest monitoring

Conveners: Miro Demol, Crystal L Schaaf, Jan van Aardt, Bert Gielen

Continued advancements in 3D scanning equipment and software open up a variety of new  perspectives on how we can map and monitor our surroundings. In a forest environment, terrestrial  laser scanning (TLS) can capture full 3D pointclouds of the environment, in relatively fast way and  with an astonishing level of detail. This has sparked interest in the use of TLS for measuring  traditional forest inventory metrics, such as tree diameter and height, crown dimension and stem  positions, but its greatest potential lies in measuring novel structural tree properties, such as woody  biomass, aboveground root structures, and even foliar structural properties, that were practically  impossible to quantify at this level of detail, accuracy, and precision before. In this session, we want  to explore the potential contribution of TLS for improved forest monitoring, detailed assessments of  complex forest structures, and investigate how TLS integrates with other sensors and platforms.

Subtheme 2: The use of mobile measurements and modeling for emissions quantification and mitigation

Conveners: Felix Vogel, Thomas Röckmann

Long time observations of greenhouse gas concentration are indispensable for monitoring global and regional trends in atmospheric greenhouse gas concentrations on large scales. However, emissions and emission reduction actions happen at the local scale where emission estimates usually rely on “bottom-up” assessments using activity data and emission factors. The underlying emission factors are often not site specific or independently confirmed by top-down measurements. Recently developed mobile greenhouse gas analyzers are increasingly used to bridge the scale between continuous observations at fixed sites and the local emissions from individual sources, facilities or limited regions. Many mobile studies have uncovered previously unknown sources, as well as significant differences in emission factors which can differ widely even for similar sources in a region or a emission category.

We invite contributions that focus on the use of mobile measurements or novel evaluation tools of such mobile measurements for quantification of greenhouse gas emissions, and emission reduction.

Subtheme 3: Soil GHG exchange – from techniques to data analysis (past, present and future)

Conveners: Manuel Acosta, Jukka Pumpanen, Ralf Kiese

Soils act as sources and sinks for greenhouse gases (GHGs) such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Even though, last decades a significant advance regarding soil GHG fluxes studies at different ecosystems have done, there still issues and shortcomings to be solved.  On the other hand, new techniques to improve the versatility of soil GHG measurements and data interpretation have been introduced the last couple of years. Since both storage and emission capacities may be large, precise quantifications are needed to obtain reliable soil global budgets that are necessary for land-use management (agriculture, forestry), global change and for climate research.
This section invites studies addressing the soil fluxes-related processes of any of the three GHGs and their influencing parameters, studies involving techniques for GHG measurements and studies regarding soil GHG data processing and interpretation.

Subtheme 4: Estimating uncertainties of ICOS measurement data and their implication for the uncertainty of European (and global) GHGs budgeting

Conveners: Ingeborg Levin and Ute Karstens

The main question to be addressed in this session is how far are ICOS RI and its users from the aim to better understand the governing processes of GHGs exchange to enable future projections and provide input for, and possibly allow verification of, e.g. the Paris agreement. When designing and implementing the ICOS Research Infrastructure and its observational networks, huge effort has been put into measurement precision, compatibility and accuracy. Here we aim at evaluating and discussing the success of this effort, concerning, on one hand, the measurements themselves and their representativeness but also their value for our ability to quantify European and global GHGs fluxes and budgets. The session invites presentations assessing our current measurement uncertainties and their quantification, the completeness and representativeness of the existing networks, and finally the integration of bottom‐up versus top‐down flux estimates.

Conveners: Pete Smith, Are Olsen, Jean-François Soussana, Gregor Rehder, Luca Montanarella, Ivan Janssens, Cristina Arias-Navarro

The rise of atmospheric concentrations of carbon dioxide due to anthropogenic forcing is partly mitigated by the uptake and storage on land and in the ocean. The various parts of the land and ocean carbon sinks store carbon on very different timescales. The storage time scales at the points of uptake, e.g. the sea surface or terrestrial above-ground biomass, are seasonal to annual, or even shorter. Long-term removal of carbon from the atmosphere thus requires transfer of the carbon to a reservoir that is stable on timescales of centuries, millennia or more (sub-soil layers, deep-ocean, lithosphere). Ocean mixing, export production, organic matter burial and decomposition and soil respiration are among the processes related to the carbon cycle. The magnitude of these, typically vertical fluxes between carbon reservoirs both on land and in the ocean, are much less constrained than the surface fluxes (air-sea fluxes, net ecosystem exchange).

Closely related is the call for better managing long-term carbon reservoirs to contribute to climate change mitigation and to enhance resilience to climate change. This addresses in particular the management of soils to increase soil organic carbon (SOC) content, which would also underpin food security. This is a subject of growing international interest through initiatives such as the international ‘4p1000’ initiative and the FAO's Global assessment of SOC sequestration potential (GSOCseq) programme. Since SOC content of soils cannot be easily measured, a key barrier to implementing programmes to increase SOC at large scale, is the need for credible and reliable measurement/monitoring, reporting and verification (MRV) platforms, both for national reporting and for emissions trading, including  (1) Long term experiments (2) Short term experiments (3) SOC / GHG models (4) Spatial data to drive models (5) Activity data (6) Remote sensing (7) Spatial soil re-sampling surveys. A soil carbon monitoring system will require a strong collaboration between EC JRC, Copernicus, GEOSS (Group on Earth Observations), ICOS (Integrated Carbon Observation System), GSP (Global Soil Partnership), long-term soil studies and the integration of agricultural activities data into a global framework. In this way, the implications of projects contributing to SOC sequestration will be monitored, reported and verified at local, national and global scales through the same internationally shared monitoring system.
We invite presentations addressing the transfer of carbon from reservoirs that interact with the atmosphere on short time scales to reservoirs that will isolate the carbon for centuries or more. Contributions on both land and ocean sink as well as those addressing the different components for a MRV system of SOC change are welcome. Presentations from all thematic components of ICOS are encouraged.

Subtheme 1: Estimating CO2 fluxes and their climatic controls based on atmospheric and oceanic data

Conveners: Christian Rödenbeck, Ingrid Luijkx, Ute Karstens, Peter Landschützer

The response of the natural carbon cycle on land and ocean to environmental changes co-determines the future climate trajectory.

Sustained measurements of CO2 in the atmosphere and the ocean, collected by the extensive observational efforts within ICOS and at various institutions worldwide, have been providing a basis to quantify and understand CO2 fluxes and their relationships to climate. Additional information is provided by measurements of related tracers (isotopic ratios, COS, APO, Ar, nutrients, etc.). Traditional data-based estimation methods, such as atmospheric transport inversions, surface-ocean interpolations, etc., are being developed further to make use of the information in the multiple observational records.

The session invites presentations around data-driven estimates of the global or regional carbon cycle, its variability, its responses to climate anomalies and trends, and process attribution.

Depending on the interest from the community (TransCom, SOCOM, etc.), the results-oriented session will be accompanied by discussion workshops as side events before or after the main conference program, to discuss innovative methodological developments and/or community activities around data-driven carbon cycle estimates.

Subtheme 2: Using the ICOS network as anchor stations for investigating fluxes of reactive gases and aerosols in terrestrial ecosystems

Conveners: Christian Brümmer, Silvano Fares

Reactive gases and aerosols play a major role in atmospheric chemistry and may act as important nutrient inputs for terrestrial ecosystems. The ICOS network offers the opportunity to complement common observations of greenhouse gases with measurements of reactive gas fluxes between plant ecosystems and the atmosphere. Plant ecosystems exchange reactive trace gases, such as nitrogen oxides (NOx), ozone, and volatile organic compounds (VOCs), and particles. While some of these compounds are anthropogenically produced, many are biotic in origin and are emitted in-situ or produced from rapid photochemistry in the canopy. The oxidation products include low-volatility organic compounds that readily partition to the aerosol phase, particularly in the presence of anthropogenic pollutants such as ammonium, nitrate and sulphate.

In addition to being strong sources, soil and leaves represent major sinks of these reaction products, with deposition to the surface also as a function of surface wetness and uptake into the leaf via the stomata. The canopy region thus represents a dynamic and rapidly changing environment in which a myriad biological, chemical and physical processes occur over very short time and spatial scales. Advanced techniques of flux measurements provide good knowledge of the overall net fluxes of these compounds above canopies, while additional in-canopy measurements enable more detailed study and understanding of the individual processes and reactions driving these fluxes. These rapidly advancing measurements can support parametrization of models for a mechanistic understanding of in-canopy dynamics of deposition and emission of these reactive gases, which can in turn allow fuller interpretation of in-situ measurements and inform the design of field experiments to test specific hypotheses. This session, sponsored by ILEAPS (Integrated Land Ecosystem Atmosphere Process Study), encourages the submission of contributions based on in-situ measurements and/or modeling that improve our understanding of biosphere-atmosphere exchange of reactive gases and aerosols and in-canopy processes.

Subtheme 3: Towards more constrained methane budgets

Conveners: Annalea Lohila, Tuula Aalto

Increased atmospheric concentration of methane (CH4) is a major determinant of global warming. CH4 is being emitted into the atmosphere from both natural and anthropogenic sources, from the latter at a growing rate. While the increase in CH4 concentration slowed down in the beginning of the 2000’s and stayed stable for 6-7 years after that, we are now witnessing a new era of even more rapidly growing concentrations. The reasons for these changes are not fully understood. Also, the global CH4 budget still has considerable uncertainties, particularly regarding biogenic emissions. For example, the role of inland waters and wetlands remains uncertain. Better process understanding is needed in order to make reliable projections for the future CH4 emissions. In this session, we welcome contributions from different fields of research, such as flux and process studies, utilization of measurement networks and infrastructures, application of multiple tracers and isotopes, climate and ecosystem modelling, and the use of atmospheric data in inverse modelling.

Conveners: Erik Andersson, Huilin Chen, Greet Maenhout, Bruna RF Oliveira, Jan Pisek, Marko Scholze, Mahesh Kumar Sha, Thorsten Warneke

Greenhouse gases (GHG) in the atmosphere have been on the continuous rise since the industrialization. Both remote sensing and in situ atmospheric observations of greenhouse gases (GHGs) are increasingly available, and are essential for estimating surface fluxes of GHGs at from local to regional and continental scales. The remote sensing measurement has the advantage of providing information of GHG concentrations in an integrated path, either a vertical column or a horizontal path, and may provide a good spatial coverage when deployed on aircraft and satellites. The remote sensing measurements are useful to infer surface fluxes and to identify and quantify hot spot emissions of CO2 and CH4, although such applications are limited by the relatively large uncertainties, especially when compared to in situ measurements. On the other hand, in situ measurements can be made accurate with improved analytical techniques and available direct calibrations, but are either temporal or spatial limited. To this end, a combination of remote sensing and in situ measurements is naturally preferred. 

Ground-based solar absorption measurements of absorption of solar radiation are an important component in the global observing system. The Total Carbon Column Observing Network (TCCON) is the reference network for the validation of greenhouse gas retrievals from satellites and mobile spectrometers within the Collaborative Carbon Column Observing Network (COCCON) complement TCCON and are used for emission measurements from cities. Several satellite missions for atmospheric greenhouse gas measurements are scheduled for launch in the coming decade. Therefore, it can be expected that remote sensing measurements will become increasingly important for carbon cycle research.

The European Commission together with the European space and weather organizations are establishing a Copernicus CO2 Monitoring & Verification Support (MVS) capacity in support of the Paris Agreement. Such a CO2 MVS capacity requires multiple in-situ data as described in the Green CO2 Report.).

Ecosystems respond to changing environmental conditions with various biogeochemical reactions that influence the remote sensing signal. Advances in Earth observation technologies offer opportunities to understand ecosystem structure and function across various spatial and temporal scales. Remote sensing observations allow researchers to link trends in vegetative traitswith key ecosystem processes. Novel, cross-disciplinary approaches, integrating remote sensing with in situ and experimental measurements, can help improve the monitoring and management of ecosystem changes over time and increase the accuracy of ecosystem models.

Besides showcasing the recent advances, this theme also aims to highlight the associated challenges: What are the options for tackling the scaling gap between field and satellite measurements? How to address the temporal gap and scale up from daily observations to seasonal trends? What are the best practices to establish data quality through traceability, uncertainty, and validation? How can we separate fossil-fuel emissions from natural sources? How can ICOS contribute to tackle these challenges?

We invite presentations addressing: (1) remote sensing techniques for monitoring greenhouse gases from ground-based instrumentations; (2) Integration of long-term and campaign-based in situ and remote sensing measurements; (3) application of these measurements, such as in-situ data in support of the CO2 MVS capacity.  This session will include observations from satellite, TCCON, AirCore, aircraft, drones, and ICOS stations.  In particular the session focuses on the benefit of in-situ data in the presence of remotely sensed CO2 (such as from CO2M) and CH4 concentrations as well as the requirements on the in situ networks (station density, measurement accuracy, type of instrument). This interdisciplinary session will highlight an array of experimental, observational, and modelling studies as well as the pitfalls in using Earth observation data to address these challenges.

Conveners: Janne-Markus Rintala, Syed Ashraful Alam, Elena Saltikoff

The rapid developments due to digitalisation, globalisation and climate change are huge challenges that people are already facing. The young suffering from climate anxiety are not the only ones hungry for learning more about climate and greenhouse gases. A life-long learning entails everyone in a modern society.

ICOS data is made available to everyone. Yet its efficient use requires basic skills of i.e. the Jupiter notebook, R, Matlab etc. Student engagement using this data including educators with sparking ideas for teaching including on-line training tools, organizing of MOOC-courses, gamification and other novel ideas and techniques everyone can use to disseminate their results and making their conclusions widely known to create a societal impact needed to make necessary change in our behavior to save the planet.

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