Description of work

Climate forecast systems, which include systems based on empirical/statistical relationships and global dynamical models, predict the future evolution of climate, taking into account internal and external sources of variability, for timescales that range from a month to a few decades. The main characteristics of these systems are that they require accurate information about the contemporaneous state of the climate system and robust estimates of their quality. This makes them slightly more complex than other climate simulations because, for instance, they require sets of hindcasts (forecasts for the past performed with the same forecast system) that are very expensive to run, need an ensemble initialisation procedure to represent observational uncertainty, and rely strongly on the homogeneity in time of the observing system. Climate forecast systems are quickly becoming operational. The time scales of operational systems are expanding as decadal climate forecasting is moving towards its operationalisation following the real-time exchange of global forecasts from ten contributing centres, several of them European. Roles and responsibilities reside on the operational WMO Lead Centres for seasonal (and in the future decadal) forecasts.

The WP will collect decadal climate predictions, assess their quality, and combine them into single probabilistic sources of information according to the user needs identified both in the project and in previous initiatives and with a special focus on Europe and the North Atlantic. It will also explore new avenues for the improvement of the decadal prediction systems beyond the CMIP6 exercise. The WP will coordinate part of the European contribution to the DCPP, a CMIP6-endorsed project, and the real-time exchange of decadal predictions for WMO.

Objectives

This work package will draw on existing global climate prediction systems, collecting all the latest information and identifying the main factors that could improve their societal impact by:

  • Outlining best practices in decadal climate prediction experimental design, real-time operations and analysis.
  • Identifying the relative merits of climate decadal predictions, including the representation of regional climate trends.
  • Providing guidance on the use of existing climate predictions.
  • Exploring avenues to improve the next generation of climate predictions with experiments on the impact of resolution, initialisation, forecast drift reduction and short-term forcings.

The final goal is the integration across the European climate forecast systems developed for CMIP6 and those that will be built on them, making them a credible, reliable, authoritative, and action-oriented source of climate information to support more climate-resilient European economies and societies.