ÉCLAIRE investigates the ways in which climate change alters the threat of air pollution on European land ecosystems including soils. Based on field observations, experimental data and models, it establishes new flux, concentration and dose-response relationships, as a basis to inform future European policies.Starting with biosphere-atmosphere exchange measurements, ÉCLAIRE quantifies how global warming and altered precipitation will affect emissions of key European primary pollutants (NOx, NH3, VOCs), including interactions with increasing aerosol and hemispheric O3 background concentrations, modifying atmospheric transport and deposition. An ensemble of chemistry transport models will be applied to assess uncertainty in response to harmonized scenarios for climate, emissions and land-use, while high resolution studies will investigate how climate change alters local patterns of pollutant exposure and threshold exceedance.A network of European experiments for contrasting ecosystems and climates, combined with meta-analysis of unpublished datasets, will quantify how climate change alters ecosystem vulnerability to tropospheric O3 and N deposition, including interaction with increased CO2. Combined with special topics on interactions with N form (wet/dry, NHx/NOy), aerosol-exacerbated drought stress and BVOC self-protection of O3 effects, novel threshold and dose-response approaches will be developed. These will be combined with regional atmospheric and biogeochemical models to estimate interactions and feedbacks on plant/soil carbon stocks, greenhouse gas balance and plant species change.The new risk assessment chain to be developed will be applied at the European scale, quantifying how projected climate change will alter damage estimates. Combined with economic valuation of ecosystem services, improved integrated assessment modelling will allow a cost-benefit analysis to inform future mitigation and adaptation strategies on air pollution and climate change.