EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Towards improving current estimates of CO2 emissions and sinks in the Aix-Marseille metropolis area, France, and developing virtuous CO2 mitigation scenarios in link with local stakeholders and socio-economic actors.

Irène Xueref-Remy1, Brian Nathan1, Mélissa Milne1, Ludovic Lelandais1, Aurélie Riandet1, Thomas Lauvaux2, Huilin Chen3, Sanne Palstra3, Bert Scherren3, Alexandre Armengaud4, Pierre-Eric Blanc5, Jocelyn Turnbull6, Marie-Laure Lambert7, Frédérique Hernandez7,8, Valéry Masson9, Christophe Yohia10, and Antoine Nicault11
Irène Xueref-Remy et al.
  • 1IMBE Mediterranean Institute of Biodiversity and of marine and continental Ecology, Aix-Marseille University, Aix-en-Provence, France (
  • 2LSCE Laboratoire des Sciences du Climat et de l'Environnement, University of Versailles-Saint-Quentin-en-Yvelines, Gif-sur-Yvette, France (
  • 3RUG CIO Centre for Isotope Research, University of Groningen, The Netherlands (
  • 4Atmosud, Regional Agency for Air Quality monitoring, Marseille, France (
  • 5OHP Observatoire de Haute Provence, UMS Pytheas, CNRS, Saint-Michel-l’Observatoire, France (
  • 6GNS Science, Lower Hutt, New-Zealand (
  • 7LIEU Laboratoire Interdisciplinaire Aménagement Urbanisme, Aix-en-Provence, France (
  • 8IUAR Institut d'Urbanisme et d'Aménagement Régional, Aix-en-Provence, France (
  • 9CNRM National research center on meteorology, Toulouse, France (
  • 10OSU PYTHEAS, Service Informatique, Marseille, France (
  • 11GREC-SUD Group of climate experts of the PACA region, Marseille, France (

Most of the world population leaves in urbanized areas, and this is expected to expand rapidly in the next decades. Cities and their industrial facilities are estimated to emit more than 70% of fossil fuel CO2. Still, these estimates, mostly based on bottom-up emission inventories, need to be verified at the city scale. Atmospheric top-down approaches are a tool of choice in this sense. They rely mostly on continuous atmospheric CO2 measurements inside and outside of the studied urbanized area to catch the urban plume and its variability (either from in-situ, remote sensing or airborne instrumentation), on the use of emission tracers such as carbon monoxide and black carbon for combustion processes, of volatile organic compounds and of carbon isotopes to distangle the contribution of natural, modern and fossil fluxes, on mass balance approaches  which needs measurements of the atmospheric boundary layer height, and on direct and inverse modeling frameworks. Furthermore, as they represent the main anthropogenic CO2 emission sector, cities and industrial facilities are strategic places where actions on mitigating CO2 emissions should be undertaken in priority.

The Aix-Marseille metropolis (AMm), located in the south-east of France, is the second most populated area of France (1.8 M inhabitants). It is also much industrialized, and is located in the SUD-PACA region, which is strongly exposed to the risks of Climate Change. Since 2017, two top-down research projects have been funded by the LABEX OT-MED (AMC project, 2016-2019) and by the French National Research Agency ANR (COoL-AMmetropolis project, 2020-2024) to fullfill the following objectives : 1/ assessing the spatio-temporal variability of atmospheric CO2 in the AMm area ; 2/ characterizing the different sources and sinks that control CO2 through the use of tracers and carbon isotopes ; 3/ verifying independently the high-resolved CO2 emission inventory delivered by the regional air quality agency ATMOSUD ; 4/ developing a direct modeling framework, facing challenges such as the complex AMm topography, coastal boundary layer dynamics, and some specific meteorological features that are mistral and land/sea breezes ; and 5/ developing scenarios to the horizon 2035 for mitigating AMm CO2 emissions and find the most effective way to integrate vertuous scenarios, defined in interaction with stakeholders, into legal and urban planning schemes, tools, charters or practices. A synthesis of the results obtained until now from these two projects will be presented.

How to cite: Xueref-Remy, I., Nathan, B., Milne, M., Lelandais, L., Riandet, A., Lauvaux, T., Chen, H., Palstra, S., Scherren, B., Armengaud, A., Blanc, P.-E., Turnbull, J., Lambert, M.-L., Hernandez, F., Masson, V., Yohia, C., and Nicault, A.: Towards improving current estimates of CO2 emissions and sinks in the Aix-Marseille metropolis area, France, and developing virtuous CO2 mitigation scenarios in link with local stakeholders and socio-economic actors., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12629,, 2021.

Corresponding presentation materials formerly uploaded have been withdrawn.