Fifteen thousand excess deaths in the European heatwave of summer 2003, and earlier events of a similar nature in other parts of the globe, shows that society lacks operational capabilities to provide adequate medium-range (3-7 day) & short-range (1-3 day) forecasts for natural disasters involving atmospheric chemistry & dynamics.

The GEMS Consortium (to be funded by the EU in the period 2005-2008) will create new European operational capabilities for medium-range & short-range air-chemistry forecasts, through much improved exploitation of satellite data. The GEMS consortium comprises

- ten leading research labs with capabilities & models on all aspects of atmospheric chemistry,

- ten regional centres, most with operational responsibilities for regional air-quality forecasting,

- two leading European labs, ECMWF with global operational weather capabilities, & the EU's JRC with global diagnostic capabilities.

The science teams & ECMWF will develop a global operational medium-range forecast / assimilation capability for dynamics & composition, exploiting all available satellite data. The global forecasts will provide key information on long-range transport of air pollutants to the regional forecast models, through the forecast boundary conditions used by the regional systems. The improved regional forecasts will be used by air-quality authorities at city level, in dozens of cities across Europe.

The integrated forecast / assimilation capability will provide a powerful monitoring capability for greenhouse gases, reactive gases and aerosols. Sophisticated new inversion methods will be developed to infer surface fluxes of CO2 and other species through use of the surface flask data with the gridded atmospheric fields on transport & composition. The GEMS project will produce global retrospective analyses of the atmospheric dynamics and composition for the troposphere & stratosphere, and will be able to assess the impact of changes both on global & regional scale, examining extremes as well as means.

The real-time & retrospective GEMS data products will provide valuable new analysis & forecast products for regional & local users. The powerful monitoring capabilities will serve policy users in the area of treaty validation (Kyoto, Montreal, CLRTAP) & science users.