WP 3 – Impacts of reactive emissions from volcanoes and fires on the atmosphere

This WP will focus on the emissions by volcanoes and vegetation fires, which both release highly reactive gases and particles, affecting the global radiative balance of the atmosphere. We will combine fundamental laboratory studies, field measurements and numerical modelling to fully characterise these sources of gases on a global scale. The two main targets are thus:
1 – Volcano emissions: we will interact with colleagues from WP1 predicting gas emissions by through experimental and degassing model studies of the behavior of volatiles in magmas via high-temperature and high-pressure “volcano-in-a-laboratory” experiments including novel PLANEX-Equipex on-line measurements (ISTO). Laboratory and field-measurements (LOAC, electrochemical sensors, OrbitrapTM) elucidating the physico-chemical interactions of volcanic emissions entering the atmosphere will underpin the development of a chain of numerical models of the plume gas-particle processing and impacts, from high-temperature chemistry in the crater to the near-source concentrated plume or eruption column, to the dispersed plume on regional and global scales. An important aspect will be to integrate chemical kinetics aspects parameters into models simulating the chemical evolution of plumes. In future, we alsoIt is also planned to include isotopes (for tracing processes) in relation with WP1 and metals (whose emissions are intertwined with volcanic halogen-sulfur processes).
2 – Vegetation fires: their number has increased over the past few decades due to global warming and land use change. Exploiting the synergy within VOLTAIRE 2 on greenhouse gases emissions by peatlands and their reactivity, we will complement the WP2 studies by characterizing the peatlands emissions during fire periods. The chemical transformations affecting the fire emissions and the formation mechanisms for secondary species will be investigated using the HELIOS simulation chamber. In particular, the HOx/ROx radical chemistry governing the day-time chemical transformations and secondary aerosol formation will be studied investigated using instrumentation developed during VOLTAIRE 1, and the contribution of the night-time chemical transformations involving N2O5, NO3 and O3 will be studied. For this purpose, a specific instrument (CRDS) is being built in collaboration with NOAA and Colorado State University. Balloon and aircraft campaigns during fire periods in Africa, Canada and Russia polar regions (CNES-INSU programs and the H2020 European project HEMERA) are planned using the new instruments developed in VOLTAIRE 1. A campaign in the Amazonian intertropical zone is also foreseen from 2022 by CNES due to the importance and specificity of this region in terms of vegetation type, global anthropic threat and meteorology.
All these measurement campaigns combined with global modelling will contribute to the assessment of the overall impact of seasonal (summer) fires occurring each year on the dynamic and chemical functioning of the global atmosphere, in relation with climate change and stratospheric ozone balance.

As stated above, the measurement will also be used to merge the ORCHIDEE-PEAT-CH4 model developed during VOLTAIRE 1 with the fire sub-model SPITFIRE present in ORCHIDEE to create a new surface model modelling the global fires, in relation with WP2. To properly assess the impact of these emissions, such as radiative effects, it will also be necessary to more realistically represent convection phenomena such as pyro-convection and photo-phoresis in the model dynamical codes (WACCM and LMDz). All these efforts will contribute to improve the radiative balance of fires in the future IPCC AR7 exercise.

Economic Impacts: Carbon valuation and mitigation policies
Economic models of global warming aim at valuing the economic effects of the reduction of GHG emission, through a “social cost of carbon” compatible with the IPCC global warming scenarios (generally the 1.5° scenario). By the time being, while most world emissions are not priced, carbon markets and taxes have been implemented, mainly in Europe. In VOLTAIRE 1 some works have been already done on the fixation of carbon price on the ETS European market (ETS) and on the regional effects of carbon taxation on poverty and income inequalities, that will be continued. Another research strand has been developed in the field of Carbon Capture and Storage (CCS), through a long-term cooperation within the VOLTAIRE consortium, in particular the BRGM and LEO. Considered by its proponents as a cost-minimizing mitigation technology, CCS deployment should nevertheless require a massive policy support and a high carbon price. It raises technical and economic debates that could be fed by the contributions of the VOLTAIRE 2 WP1 and WP3.