Towards prediction of decadal climate variability and change

There is growing interest in the field of decadal climate prediction, supported by observational evidence of natural decadal climate variations with significant regional impacts, and evidence of potential skill from idealized predictability studies and pioneering attempts at predictions obtained by initializing climate models with observations. A synthesis of the current state of observed decadal climate variability (DCV) characteristics and some examples of DCV impacts on climate on land is given. Aspects of DCV arising either from internal climate variability or from natural external forcing were described. The potential predictability from these sources, and also from the influence of anthropogenic external forcing is considered. As this new area of climate science is at an early stage, a number of significant challenges need to be addressed if practical prediction systems capable of producing credible projections at regional scales for use by scientists, stakeholders and planners are to be provided and summary of these challenges is given.