and strategies (including the option of not making a decision and allowing “business as usual”). Table 4.1 demonstrates an array of tools commonly used to aid effective decisions and actions related to climate change. Decision tools are as old as the human race itself, ever since the days when the peoples of the earth prognosticated about the future by studying the motions of the stars and planets, interpreted messages hidden in the entrails of animals, and consulted oracles. In modern times, decision methods based on expert judgments, deliberative consultations, historical records, and actuarial analyses slowly replaced those earlier methods in many regions of the world. Currently, computer-based information systems are extremely significant in helping decision makers use data and models to improve their decision making capabilities. In line with contemporary society’s reliance on information technology and with advances in the art and science of visualization, there are now a wide variety of computer-based tools to help inform effective decisions and actions related to climate change. These include earth system models, impact models, various economic modeling techniques (including cost-effectiveness and cost-benefit analyses), integrated assessment models, and a range of other computer-based tools and products for engaging users and the public in deliberative decision processes or for helping them access and evaluate information related to alternative strategies. Many tools now include explicit consideration of uncertainties and are able to incorporate spatial detail through the use of Geographical Information Systems (GIS).
But many decision makers use a basic set of accessible decision support tools that include graphs, maps, images, GIS, and spreadsheets. One example of the demand for decision tools is that of local water managers. At a 2008 workshop, hosted by the Arizona Water Institute, participants identified a need for tools that provide information on how the accuracy of hydrological variability, patterns of seasonality, and groundwater might change with climate warming, improved snowmelt/runoff models, strategic monitoring of summer precipitation, groundwater recharge, and water quality. Participants also requested tools with better visualization and explanation of data limitations and more personal engagement with scientists providing decision support (Jacobs et al., 2010).
Although a wide spectrum of tools currently exists, few have the capacity to work across international, national, regional, and local scales. The fact that so many tools exist can also create confusion on which tools are the most appropriate for particular decisions. Additionally, the same tool used with different assumptions or design specifications may result in different results. Decision makers often turn to federal or state agencies, local universities, and national or international assessment reports to provide information on the merit of such tools to support climate-related decisions.