This talk by Dominik Brunner (Empa) at the 1st CHE General Assembly presented an overview of the activities in Work Package 2. WP2 (Coordinating Efforts on Library of simulations for emissions and atmospheric transport) will generate a library of realistic CO2 simulations for present-day and future emission scenarios, “nature runs”, from the global to the regional scale to serve as input for other WPs. In a wider framework, they will also support the assessment of the requirements for a future space mission and the challenges introduced by the issues listed above. The model simulations will be based on current and future emission scenarios and cover a range of scales, from 1 km for a regional domain to 10 km for a global domain. In addition, specific simulations for point sources at sub-kilometre scale will be provided.