U.S. Environmental Protection Agency


Date of this Version



Published in ENVIRONMENTAL MODELLING, SOFTWARE AND DECISION SUPPORT: STATE OF THE ART AND NEW PERSPECTIVES, edited by A. J. Jakeman, A. A. Voinov, A. E. Rizzoli, & S. H. Chen (Amsterdam et al.: Elsevier, 2008).


Scenario analysis is the process of evaluating possible future events through the consideration of alternative plausible, though not equally likely, states (scenarios). The definition by the Intergovernmental Panel on Climate Change (IPCC) best represents scenarios considered in the natural sciences:

"A scenario is a coherent) internally consistent and plausible description of a possible future state of the world. It is not a forecast; rather, each scenario is one alternative image ~fhow the future can unfold."(http://ipcc-ddc.cru. uea.ac.uk/ ddc_definitions. htnll)