Chris D. Hewitt, Jason A. Lowe
Bulletin of the American Meteorological Society, 99/10 American Meteorological Society USA 2018
Information on the future climate is an essential basis for managing the risks, as well as potential opportunities, arising from a changing climate. Typically, this information comes from state-of-the-art numerical simulations of the climate in the form of climate predictions and climate projections. Climate predictions are based on simulations that are initiated from the present-day state of the climate and can extend out to several years in the future (typically a decade or less). Climate projections simulate the longer-term (decades) response to a scenario of changes in greenhouse gases and other radiative forcings, and are often initiated from a preindustrial climate.
For many decision-makers and policymakers the information available from climate simulations is not at the appropriate spatial and temporal scales they need to form the basis for their climate-related risk assessments or for climate action plans such as national climate adaptation programs. In addition, there are a range of methods and products that provide information on future climatic conditions. As a result, multiple lines of sometimes conflicting evidence often complicate adaptation planning and risk assessments. For example, there are several well-established but different national approaches to producing projections of climate change and informing national adaptation plans. Also, some decision-makers require information that spans a range of time scales from a few months or a year ahead to decades into the future. The scientific community has not yet managed to respond by providing usable climate information over this range of time scales in a transparent and robust way for many of the decision-makers.