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Carbon Cascades from Land to Ocean in the Anthropocene

Periodic Reporting for period 1 - C-CASCADES (Carbon Cascades from Land to Ocean in the Anthropocene)

Reporting period: 2015-01-01 to 2016-12-31

The most recent Intergovernmental Panel on Climate Change Assessment Report (5th IPCC AR) includes the transport of carbon across the Land-Ocean Aquatic Continuum (LOAC) as a key component of the global carbon cycle but fails to quantify the historic changes of this transport due to human activities (land-use and climate change, hydraulic management, and agricultural, domestic and industrial activities). Earth System Models also do not account for the lateral flows of carbon and associated greenhouse gas (GHG) exchange with the atmosphere. This is a major knowledge gap because these fluxes have recently been demonstrated to contribute significantly to policy-relevant global and regional carbon budgets in high-profile research papers. In the absence of this assessment, large uncertainties remain concerning the fate of the anthropogenic CO2 emitted into the atmosphere and its potential impact on climate projections.
To make a breakthrough in this field, the ‘C-CASCADES – Carbon Cascades from Land to Ocean in the Anthropocene’ project was launched on January 1st, 2015. The ambition is to significantly advance the predictive capability of Earth System Models (ESMs) by integrating within them observations, analyses and mechanisms of the carbon transfer in the LOAC. The 3 science objectives are to:
• Understand the critical mechanisms that transport carbon in the LOAC from technical developments, observations and experiments (WP1)
• Assess carbon transfers in the LOAC for selected “hotspot” regions and river catchments (WP2)
• Model the LOAC at the global scale, for attribution of historical changes and future feedbacks on climate (WP3)
In addition, C-CASCADES will deliver policy-relevant tools and technological innovations to agencies responsible for environmental monitoring.
C-CASCADES aims also to train 15 Early-Stage Researchers (ESRs) both as future scientists and scientifically trained professionals, able to pursue a successful career in academia, industry or the policy-sector.
Once hired, the 15 ESRs began to do extensive literature reviews and learn about their new research tools. Significant progress has already been achieved, which is described below by Work Package:

1. WP1 - Process understanding: Technical development, observations and experiments:
So far, the key outcomes for each ESR project can be summarised as follows:
• Sensors able to continuously measure CO2, CH4 and O2 concentrations in water have successfully been developed and tested in the Baltic Sea
• Extensive field and laboratory work to identify and quantify seasonal sources of CO2 in Alpine streams showed a dominant contribution of ground water in winter
• Sampling of soil, sediment and water in a Brazilian reservoir has been carried out to provide new insights on pathways and dynamics of particulate organic carbon
• In boreal inland waters, carbon transformation processes are less efficient than previously assumed and CO2 concentrations didn’t increase over the last 20 years
• In the Seine River, CO2 concentrations appear to be dependent to the seasons and to the level of urbanisation: they are highest in spring and in big cities
More exciting outcomes are expected during the second half of the project. Indeed, since WP1 is very field orientated, most of the interpretation can only be done once all data have been collected.

2. WP2 – Regional scale applications: benchmark studies on hot-spot areas:
Each ESR has started to study the relevant “hot-spots”, selected on the basis of their global relevance, contrasting behaviour and potential for major changes. Several highlights have already emerged:
• The lower Danube river system has revealed very high supersaturations in CO2, and thus being a strong source of CO2 to the atmosphere
• The dynamics of the mobilization and transport of particulate organic matter from the land into aquatic systems can be well modelled with existing parameterizations and models for Europe (soil class maps, crop cover and hillslope estimates)
• After a comprehensive data compilation on Amazon river-plume-coastal biogeochemistry, the Regional Oceanic Modeling System (ROMS) has been set-up for the simulation of hydrodynamics and transport in the study area
• Arctic circulation appears to be the dominant supply of anthropogenic CO2 in the deep Arctic, implying that sea ice retreat effect is moderate on the evolution of the anthropogenic CO2 inventory in the interior Arctic
• Laboratory experiments of permafrost thawing have been performed to compensate the lack of data and allowed to set-up preliminary runs with the model JSBACH
The model-based studies are all well under way with first results already published. The ESRs are currently deep in the application and analysis stage, with new results being produced at a rapid pace.

3. WP3 – Global scale modelling and feedbacks on Earth system processes:
After literature reviews and designing, coding, and improving model components, first results have been achieved:
• Improved quantification of carbon fluxes in lakes and reservoirs at a high spatial resolution for the boreal region is promising in terms of adding yet another missing carbon pool into existing ESMs.
• A comprehensive neural network approach is being developed to quantify the benthic-pelagic coupling on the scales ranging from estuarine to the abyssal ocean.
• Progress has been made in incorporating Dissolved Organic Carbon leaching with subsequent transformations in rivers into the terrestrial carbon cycle components of Earth system models, such as JULES and ORCHIDEE.
• The dynamical representation of nutrients and carbon riverine fluxes into the ocean has been implemented: it’s an important step towards addressing the exchange of carbon between the coastal and the open ocean.
While focusing on very specific goals, the work in this WP is on its way towards a more holistic understanding of the fate of carbon across the land ocean continuum.
The strength of C-CASCADES is to integrate different system studies, processes and scales and to bring together scientists from different fields. This is a great added value and it will help to make a breakthrough in understanding the LOAC response to human-induced perturbations, to deliver more accurate carbon budgets and to assess the impact of greenhouse gas emissions on future climate.
In terms of strengthening European innovation capacity, C-CASCADES contributes to the generation of a dynamic, highly skilled, and scientifically excellent group of young scientists ready to address the future challenges of Earth system science, thanks to the structuring effect of a strong interdisciplinary network. The access of training events to other researchers broadens the impact of the project (25 so far).
In terms of socio-economic impact, C-CASCADES will contribute to construct well-founded policies and to translate scientific results into operational models supporting the decision making process, e.g. implementation of the scientific results into a modelling platform (D-WAQ) that is used worldwide by water managers and consultants (Deltares); innovation in sensor technology (KM Contros); implementation of new models in the context of wastewater treatment and discharge to the environment (Veolia); implementation of all C-CASCADES data in the Global Carbon Atlas of the Global Carbon Project (